@ 1974

KARL DEE SMITH

ALL RIGHTS RESERVED

---

ORGANOSCANDIUM CHEMISTRY

by

KARL DEE SMITH

A DISSERTATION

Submitted in partial fulfillment of the requirements

for the degree of Doctor of Philosophy in the

Department of Chemistry in the

Graduate School of The

University of Alabama

UNIVERSITY, AL1\BAMA

1973

e····

ACKNOWLEDGMENTS

The author wishes to express his deep appreciation to:

Dr. D. F. Smith and Dr. B. W. Ponder for their understanding, encouragement, and guidance throughout the course of this research.

Steve Seale for his many hours spent in setting up a workable computer library to permit the completion of this work to become a reality.

Merle Watson for his many services rendered in the making of the special glass apparatus needed throughout the course of this work.

The computer operators, Steve Watson, Mike Webb, Bob McGwier, Al Martin, and Bill Gammon for their cooperation in efficiently running the hundreds of computer programs needed for the completion of this work.

Sam Hassel, G. M. Nichols, and Harold Moore for their many services rendered in the maintenance, stockroom,

and electronics fields, respectively.

The secretaries for their services rendered.

Segail Friedman for typing the final manuscript of this work.

His wife, Becky, .and to Angela and Christopher for their confidence, encouragement, understanding, and love shown in every way.

ii

I I

......___

TABLE OF CONTENTS

Page

ACKNOWLEDGivIENTS ii

LIS'l' OF TABLES iv

LIST OF FIGURES vi

Chapter

I. INTRODUCTION

II. EXPERIMENTAL METHODS

1

9

III.

Inert Atmosphere Glove Box .

Reagents and Solvents . . • • • 9

Preparation of Compounds . . • • • . • • • . 11

Preparation of Samples . . • . . • • • . • • 18

Computer Programs . • . . • . . . • • . 19

Instrumentation . • • • . • • • 20

RESULTS AND DISCUSSION 22

Dicyclopentadienylscandium Chloride

Dimer . . . . . . . . . . . . . . . . . . 22

Tricyclopentadienylscandium . • . . . . • . 41

Trichlorotris(tetrahydrofuran)scandium . 63

Bis (indenyl) magnesium . . . • • . . • • 84

IV. CONCLUSIONS . . . . . . . . . . . . . . . . . 112

REFERENCES . . • . • 114

iii

• •

. .

•

9

;,

}

;

LIST OF TABLES

Table Page

1. Elemental Analysis of Scc13 . • • • • . • • 14

2. Elemental Analysis of Mg(C9H7)2 • • • . • . 16

3. Elemental Analysis of Sc(C5H 5)3 . • . . . • 18

4. Final Atomic Positional Parameters a,b

for[<c5H5)2 ScCl]2 . . . . . . . . . . . . . 27

5. Anisotropic Temperature Factors a, b(x 10 4

) for[<c

5H 5)

2sccl) 2 . . . . . . . . . . . . . . 29

6. Observed and Calculated Structure Factors forthe Dicyclopentadienylscandium Chloride Dimer . . . . . . . . . . . . . . . . 31

7. Interatomic Distances (A) and Angles (deg) for[<c

5H

5)2

scc1]2

• • • • • • • • • • • • • • 37

8. Best Weighted Least-Squares Planes for[ ( CS HS ) 2 S cC 1] 2 • • • • • • • • • • • • 4 0

9 . 1 . . . 1 a, b ,

f . Fina Atomic Positiona Parameters orTricyclopentadienylscandium. . . • . 48

lo A· t · t t a

,b

(x 104

) for . niso ropic Tempera-ure Fae ors Tricyclopentadienylscandium. . . . • • . • . 49

11. Ob served and Calculated Structure FactorAmplitudes for Tricyclopentadienylscandium 50

12. Interatomic Distances (A) and Angles (deg)for Tricyclopentadienylscandium 55

iv

0

0

i

Table

13.

14.

15.

16.

Comparison of Metal-Cyclopentadienyl Carbon Bond Distances . . . • . • •

Best Weighted Least-Squares Planes for

Tricyclopentadienylscandium . . • . •

Comparison of Crystal Data for Sc(C5

H5

)3

and Sm(C5

H5

)3

. • . . • • • . • • •

a Final Atomic Positional Parameters

for ScC13

(C 4

H8

O) 3

• . . . • • • • • . • •

. a, b(

4 17. Anisotropi� Temperature Factors x 10 )

Page

57

58

63

69

for ScC13

(C4

H8

O) 3

. • . . • • . • • . • • 70

18. Observed and Calculated Structure Factors for

Trichlorotris(Tetrahydrofuran)scandium • . • 71

19. Interatomic Distances (A) and Angles (deg)

for ScC13

(C4

H8O)

3 . • • . . • 79

20. Best Weighted Least-Squares Planes forScC1

3(C

4H

8o)

3 . . . • • • • . • . 84

21.

22.

a, bFinal Atomic Positional Parameters for

Diindenylmagnesium

Anisotropic Temperature Factors a

,b

(x 104

)

for Diindenylmagnesium . . • .

23. Observed and Calculated Structure FactorAmplitudes for Bis(indenyl)magnesium

24. Interatomic Distances (A) for Angles (deg)

25.

for Diindenylmagnesium

Best Weighted Least-Squares Planes for

Diindenylmagnesium . • . . • • . • .

V

91

93

95

104

110

0

0

LIST OF FIGURES

Figure Page

1.

2.

Molecular structure of the dicyclopenta­dienylscandium dimer which lies in a general position in the unit cell • . •

Molecular structure of the dicyclopenta­dienylscandium dimer which lies on a center of symmetry in the unit cell . •

3. Structure and unit cell packing of_ tricyclopenta­dienylscandium. The atoms are displayed as the 50% probability ellipsoids for

33

35

thermal motion • . • • • • • . • • • • • 52

'4. Bond distances and angles within the cyclopentadienyl groups for Sc(C

5H

5)

3• . • • • • • • • • • • • •

5. The coordination sphere of the scandium ionwith the 50% probability envelopes of the anisotropic thermal ellipsoids • . •

6. Molecular view of trichlorotris(tetrahydro­furan)scandium with the 40% probability envelopes of the anisotropic thermal

60

73

ellipsoids . . . . . . . . . . . . . . . . . 75

7. Structure and unit cell packing of trichlorotris­(tetrahydrofuran)scandium. The atoms are displayed as the 40% probability ellipsoids for thermal motion . • • • . . . • 77

8. View looking down the Cl-Sc-0 axis displayingthe configuration of the THF rings • . • • • 82

vi

Figure

9.

10.

11.

Illustration of magnesium(l) and its

associated indenyl rings . . • • • . . . . .

View of magnesium(2) and its associated

indenyl rings . . . . . . . . . . . . . .

Structure and unit cell packing of

bis(indenyl)magnesium . . . . . . . . . .

Page

97

99

102

12. Bond distances and angles within the indenyl

groups for Mg(C9

H7

)2

. • . • . • . • • . . • 107

vii

CHAPTER I

INTRODUCTION

The element scandium has been known for over one

hundred years, but its coordination chemistry ha s been little

studied. The lack of attention has been due, in part, to the

difficulty of obtaining a pure source of scandium, although

both the metal and oxide are now commercially available in

high purity.

Scandium is the first member of the 3d transition

series and has a 3d1

4s2

ground state electronic configura­

tion. The +III oxidation state is the only one known. It

is in many respects quite similar to yttrium and the

lanthanides (1) although the di stinctly smaller radius of

the scandium(III) ion affords some noteworthy difference s

in chemistry.

Several coordination compounds of scandium have been

synthesized recently (2), although f ew structural character­

izations of scandium complexes have been reported. At the

time this work was initia.ted only the structural character­

ization of the scandium formate complex (3), Sc(HCOO}3

, had

1

been reported. In this compound, -the scandium(III) ions

2

are six-coordinate in a polymeric framework with formate

ions acting as bridging groups. X-ray structural character­

izations of dicyclopentadienylscandium chloride (4),

tricyclopentadienylscandium (5), and trichlorotris(tetra­

hydrofuran)scandium have now been carried out. In addition,

the X-ray structure of tris(acetylacetonato)scandium(III) (6)

has been recently reported.

Other organoscandium compounds which have been

characterized by means other than X-ray methods are dicyclo­

pentadienylscandium acetate, (c5

H5

)2

ScOCOCH3

; dicyclopenta­

dienylscan.di um acetylacetonate, (C5

H5

) 2

ScAcac; (allyl)

dicyclopentadienyscandium, (c5

H5

)2

sc(CH2

CH=CH2

); and

(dicyclopentadienyl)phenylethynylscandium, (C5

H5

)2

ScC=CPh

(7,8). Molecular weight measurements and infrared studies

showed dicyclopentadienylscandium acetate to be · dimeric

with bridging acetate groups. Dicyclopentadienylscandium

acetylacetonate is monomeric and infrared studies showed

the acetylacetonate to be bidentate. It was indicated that

(allyl)dicyclopentadienylscandium was monomeric and the spin

decoupled PMR spectrum confirmed the symmetrical nature of

the allyl group. It was suggested that

-

t i

I

I f

I

I

(dicyclopentadienyl) phenylethynylscandium is associated to

some extent with probably bridging PhC=C groups (9).

3

Stable organoscandium compounds characterized so far

are those containing anions in which unsaturation is present

and TI bonding may occur between the organic anion and the

scandium(III) ion. Attempts to synthesize alkyl-scandium

compounds have met with limited success. There has been no

confirmation (7) of the reported synthesis of Sc(Et)3

-Et2

o

(10). The scandium-ethyl species' instability may be due to

the alkene elimination reaction which is a well known method

of decomposition of transition metal alkyls (11). Recently,

Witt and Melson (12) reported the synthesis of organoscandium

compounds containing the trimethylsilylmethyl anion. This

anion has been used to prevent alkene elimination reactions

and enable compounds containing transition metal-carbon

bonds to be isolated (11, 13, 14, 15). They isolated the two

From available infrared and mass spectral evidence it was

concluded that both compounds contain covalent Sc-C bonds.

With the lack of unsaturation in the anion these bonds

should be purely sigma in type. They propose that the com­

pounds are polymeric with both terminal and bridging

4

trimethylsilylmethyl anions where the terminal Sc-C bonds are

2-electron, 2-center bonds whereas the bridging bonds are

weaker 2-electron, 3-center bonds.

The isolation of these compounds containing Sc-C

sigma bonds suggests that the instability of the scandium­

ethyl species is due to a facile decomposition process, e.g.,

ethylene elimination (16) rather than an instability inherent

with scandium-carbon bonds.

The structural studies of many organoscandium com­

plexes should determine their potential catalytic applica­

bility. In view of the importance of other first row transi­

tion elements as catalysts in industrial processes such as

hydrogenation, polymerization, oligomerization, etc., the

field of organoscandium chemistry and also the synthesis of

species containing scandium in oxidation states other than

three should receive increasing attention. A review of the

influence of ligands on the catalytic activity of a transi­

tion metal catalyst by Olive and Olive (17) stresses the need

for a large number of systematic studies to be carried out

so as to deepen the understanding of transition metal

catalysis and to avoid misinterpretations.

5

Soluble transition metal complexes have become

extremely important as catalysts for a wide range of reac­

tions over the past few decades. Probably the starting point

of this development was the discovery by Roelen (17) in 1938

of the reaction of olefins with carbon monoxide and hydrogen

to form aldehydes which takes place on a soluble cobalt

carbonyl complex. Many reactions were subsequently dis­

covered: the oxidation of ethylene to acetaldehyde on a

palladium complex ( "Wacker Process") /

(18), the specific

hydrogenation of double bonds on a series of transition

metal compounds (19), hydroformylation on rhodium complexes

(20), the polymerization (21) and oligomerization (22} of

olefins on soluble Ziegler-Natta catalysts, and the

cyclooligomerization of acetylene (23} and conjugated

diolefins (24) on nickel.

At first the species that effected the catalysis

were mostly definite complexes such as Wilkinson's (2)

RhH(CO} [(C6

H5

}3

P]3

in hydroformylation and Vaska's (25)

complex IrCl(CO) [(C6

H5}3P]2

as a hydrogenation catalyst.

However, two fields of chemistry that also developed rapidly

at the same time led homogeneous catalysis in a new and

extremely interesting direction. On the one hand, transition

6

metals attracted growing interest in preparative coordination

chemistry causing synthesis of many new compounds, while on

the other, important advances in theoretical inorganic

chemistry (particularly ligand field theory) influenced the

thinking of catalysis chemists. The net result was that

more attention was devoted to the effects and the signifi-

cance of ligands in the transition metal complex. The

ligands of a complex that was recognized as a catalyst were

systematically modified to bring about specific changes

both in the rate of the catalyzed reaction and in the final

product in an effort to understand which physical parameters

such as s teric hindrance, -orbital energies, electron density

on the metal, etc., are involved.

In most known cases of homogeneous catalysis on

transition metal complexes, the catalytic reaction takes

place between a covalently sigma-bonded ligand R {alkyl

group, hydrogen) and a substrate molecule (olefin, CO)

. \ coordinated to the metal M, the substrate molecule being

inserted between the metal and R by a four-center reaction

(concerted reaction). This is shown schematically for an

olefin in the form�la:

R \ / I C

(Lx)M<E-ll ➔ <Lx)M-C-C-R C

I \

In this formula (Lx) stands for all the other ligands in the

complex. The catalyst may be restored to its original state

by hydrogenolysis or homolysis 1 or the same process may be

repeated (polymerization). Therefore, parameters such as

the stability of the M-R and M-olefin bonds, the transition

metal itself, and the possibility of influencing these bonds

through the other ligands L are of the utmost importance.

Extensive structural work and catalytic applications

have been carried out with titanium. Therefore, to present

a starting framework for the catalytic possibilities of

. organoscandium complexes, it is logical to compare the

structural information obtained thus far with that of

titanium, scandium's neighbor in the periodic table. A

comparison of the metal-ligand bonding and ionic radii in

titanium and scandium complexes should give some insight

to the similarities and differences of these substances.·

The purpose of this research was to investigate some

organoscandium complexes in the solid state by X-ray dif-

fraction. Since no structural characterizations of

organoscandium complexes have been done, it was hoped that

7

8

this work would form a beginning in the systematic study of

organoscandium compounds. X-ray crystallography should be

a valuable tool in obtaining physical measurements and

structural characterization of scandium complexes to deter­

mine the coordination environment for the scandium ion to

afford a basis upon which the nature of the scandium-carbon

bond could be studied and to resolve questions of stereo­

chemistry, mode of bonding and stability. Possession of

such information should then aid the interpretation of other

physical studies of these compounds and guide the synthetic

chemist in this area.

CHAPTER II

EXPERIMENTAL METHODS

Inert Atmosphere Glove Box

All preparations, transfers, and crystal mounting

procedures were carried out under a nitrogen atmosphere,

since all the compounds under investigation were sensitive

to water and air. The glove box used was purchased from

Kewannee Scientific Equipment Corporation, Adrian, Michigan.

The enclosure was the Model 2C380 with the Model 2Cl982

"Kempure" recirculating gas purification system using

molecular sieve and manganese (II) oxide columns. The

atmosphere was tested with trimethylaluminum before use;

when the atmosphere was satisfactory there was no fuming of

the compound.

Reagents and Solvents

Technical grade magnesium turnings and. indene were

obtained from Eastman Kodak Company, Rochester, New York.

The indene was freshly distilled just prior to use.

9

10

Reagent grade tetrahydrofuran, toluene, benzene, and

ethyl bromide were obtained from J. T. Baker Chemical

Company, Phillipsburg, New Jersey, and stored over sodium

wire.

Analytical reagent grade ethyl ether (anhydrous)

obtained from Mallinchradt Chemical Works, St. Louis,

Missouri, was used without further purification.

Technical grade dicyclopentadiene, purchased from

J. T. Baker Chemical Company, Phillipsburg, New Jersey, was

boiled·to produce the monomer just prior to use.

Anhydrous scandium oxide (99.9%) was obtained as a

white powder from Research Organic/Inorganic Chemical Corpora­

tion, Sun Valley, California and from Alfa Inorganic Ventron

Corporation, Beverly, Massachusetts •

.A...�hydrous scandium trifluoride (99.9%) was purchased

from Alfa Inorganic Ventron Corporation, Beverly, Massachu­

setts.

Certified A.C.S. grade ammonium chloride was obtained

from Fisher Scientific Company, Chemical Manufacturing

·Division, Fair Lawn, New Jersey.

•

..

11

Anhydrous scandium trichloride (99.9%) was purchased

from Research Organic/Inorganic Chemical Corporation, Sun

Valley, California.

Preparation of Compounds

Dicyclopentadienylmagnesium

Dicyclopentadienylmagnesium was prepared by the

method of Barber (26):

Mg+ 2c5H

6�Mg(C5H5}2 +H2

Commercial dicyclopentadiene (B.P. 170 ° C) was placed in a

flask and boiled to produce the monomer (b.p. 42 ° C}.

Cyclopentadiene thus produced was mixed with nitrogen and

passed through a Pyrex tube 1.25 inches o.d. which was

heated electrically to 600 ° C. Excess magnesium metal

turnings were supported in the furnace tube by a circle of

nichrome gauze at the tube constriction. The product fell

from the furnace as a white solid and was collected in a

three-necked flask. The unreacted cyclopentadiene was

collected in a dry ice-ethanol trap. The apparatus was

initially charged and flushed with dry nitrogen. No special

pretreatment of the magnesium turnings was necessary. The

dicyclopentadienylmagnesium was purified by sublimation in

vacuo after the unreacted cyclopentadiene contaminant had

dimerized.

Anhydrous Scandium(III) Chloride

Anhydrous scandium(III) chloride was prepared by

12

two different methods. The first preparation followed the

method of Reed (27) in which scandium oxide was reacted with

ammonium chloride according to t he equation:

Sc2

03

+ 6NH4c1➔2scc1

3 + 3H

20 + 6NH

3

Scandium oxide (0.01 mole) was mixed thoroughly with a large

excess (0.12 mole) of ammonium chloride. This mixture was

placed in a Schlenk tube, flushed with dry nitrogen, and

heated in a furnace at approximately 200 ° C for six to eight

hours. A vacuum was then app lied and the temperature of

the mixture raised to 300/320 ° C and held at this point until

all the ammonium chloride sublimed over leaving a silvery­

gray residue. This procedure was not very satisfactory,

perhaps because the product was contaminated with a carbonate

and hydrated oxide.

The second method, far superior to the first·, was

the method of Stotz and Melson (28) in which anhydrous

scandium trichloride was prepared from an aqueous medium

13

with hydrolysis of the scan dium(III) ion prevented by the

3-formation of the Scc1

6 ion. One gram of scandium oxide

was dissolved in 28 ml of hydrochloric acid (19%HC1) by

refluxing for two to three hours. The solution was allowed

to cool to room temperature and 9.0 ml of concentrated (29%)

ammonium hydroxide solution added with stirri ng. A clear

solution with pH 3 was obtained. The solution was trans-

ferred to a beaker which was placed on a hot plate, and the

water was removed by boiling until a moist solid was obtained.

The solid was dried under vacuum over P4

o10

at room tempera­

ture overnight and then transferred to a constricted Schlenk

subl imation apparatus made of quartz. The remaining water

was removed by heating under vacuum at 150 ° C for three

hours. A coarse fritted disk was then inserted in the

Schlenk tube covering the constriction. The temperature was

increased to 300 ° C, maintained at this temperature for four

hours, and then further raised to 500 ° C for an additional

thirty minutes. The ammonium chloride sublimed onto the

walls of the upper portion of the sublimator. Final heating

at 850 ° C resulted in a sublimation of white crystals of

scandium(III} chloride onto the walls of the lower portion

of the sublimator. An alysis of a sample of the resultant

L

material done by Schwarzkopf Microanalytical Laboratory,

Woodside, New York, gave the results shown in Table 1.

Analysis

Scandium

Chlorine

TABLE l

ELEMENTAL ANALYSIS OF ScC13

Calculated for Scc13

29.7%

70.3%

Diindenylmagnesium

Diindenylmagnesium was prepared by the following

reactions:

14

Found

28.6%

67.4%

Magnesium turnings (5.0g, 0.21 mole) were covered with 100 ml

of sodium-dried diethyl ether in a 250 ml three-necked flask.

One neck of the flask was fitted with a condenser which was

in turn connected to a mercury bubbler. Of the remaining

two.entrances to the flask, one was attached via a stopcock

to a high purity N2

cylinder, and one was fitted with a

seal�d tygon tube for �yringe injection of ethyl bromide.

The vessel was then flushed with N2 and 15 ml of ethyl

15

bromide (0.20 mole) was slowly added with stirring. The

solution was refluxed for two hours, at which time the ethyl

magnesium bromide Grignard reagent was of milky-white

coloration. Then with rapid N2

flow, the stopcock was re­

moved from the condenser and 14 ml of freshly distilled

indene (0.19 mole) and 100 ml of toluene were added. The

stopcock was replaced and the reaction temperature was

elevated such that the toluene solution refluxed vigorously.

All diethyl ether was driven off with a slow N2

flow rate.

After two hours, the N2

was closed off and the solution

allowed to reflux for eight more hours. Solvent was then

removed, the residue dried under vacuum, and the flask

taken into the dry-box. The substance was transferred to

a Schlenk sublimation apparatus, removed from the dry-box

and thermolyzed under vacuum at 190 ° C. The crude product

was resublimed to free the white crystalline diindenyl­

magnesium from a yellow oil contaminant. Analysis of a

sample gave the results shown in Table 2. The white

crystalline solid had no clear melting point. Decomposition

began at approximately 170° C, but sublimation was accomplish­

ed at 190 ° C under reduced pressure with some loss of

material. It was soluble in ethers, and slightly so in

16

aromatic hydrocarbons. The substance rapidly decomposed

with the slightest exposure to either H2o or o2 •

Analysis

Magnesium

Carbon

Hydrogen

TABLE 2

ELEMENTAL ANALYSIS OF Mg(C9H7 ) 2

9.6%

84.9%

5.5%

Dicyclopentadienylscandium Chloride

Found

9.8%

85.5%

5.6%

Dicyclopentadienylscandium chloride was prepared by

the method of Coutts and Wailes (8). A solution of

dicyclopentadienylmagnesium {3.08g) in tetrahydrofuran

{50 ml) was added slowly with ice cooling to sca~dium

trichloride {3.03g) in THF {50 ml). After addition was com­

plete the solution was warmed to 50°C for one hour, at which

stage it was pale yellow in color. Solvent was removed under

reduced pressure and the residue was sublimed at a tempera-

-3 ture of 220°C and 10 mm Hg giving large yellow-green

crystals of dicyclopentadienylscandium chloride.

17

Tricyclopentadienylscandium

Tricyclopentadienylscandium was prepared by the

sealed tube reaction of dicyclopentadienylmagnesium with

scandium trifluoride (29). Dicyclopentadienylmagnesium

(0.0032 mole) was thoroughly mixed with scandium trifluoride

(0.002 mole) and placed in a bomb tube in the glove box.

After sealing under vacuum, the tube was placed in a beaker

of beeswax at 220°C and rotated by use of a magnetic stirring

bar in the beeswax. The tumbling action served to mix the.

slurry of molten dicyclopentadienylmagnesium and solid

scandium trifluoride during reaction. After a reaction time

of three hours the product was transferred to a Schlenk

sublimation apparatus in the dry-box. The tricyclopenta­

dienylscandium was freed of excess dicyclopentadienyl­

magnesium by heating under vacuum at 100-200°C and then

sublimed as straw colored needle shaped crystals from the

-4 reaction residue at 220°c at 10 mm ~g. Analysis of a

sample gave the results shown in Table 3.

. .

Trichlorotris(tetrahydrofuran)scandium

In a dry-box, scandium trichloride (0.0026 mole)

was dissolved in tetrahydrofuran (25 ml)· in a three-necked

flask. The solution was refluxed gently for three to four

Analysis

Scandium

Carbon

Hy,drogen

TABLE 3

ELEMENTAL ANALYSIS OF Sc(C5H5) 3

11.4%

81.8%

6.8%

18

Found

12.5%

80.3%

7.3%

hours at which time the solution was red in color. Solvent

was then partially removed and the flask taken into the dry­

box. The solution was transferred to bomb tubes. Slow

evaporation of the solution allowed formation of orange,

plate-like crystals of trichlorotris(.tetrahydrofuran)­

scandium.

Preparation of Samples

X-ray Diffraction

Crystals of dicyclopentadienylscandium chloride,

tricyclopentadienylsoandium, and diindenylmagnesium were

grown by slow sublimation in a sealed, evacuated tube.

Crystals were mounted in 0.2 or 0.3 mm thin-walled glass

capillaries with the aid of a small amount of stopcock

grease. The capillaries were sealed with beeswax and then

19

taken outside the dry-box and sealed with a mini-torch. The

crystals were then examined under a polarizing microscope

and one giving good extinctions was affixed to a goniometer

head for X-ray study.

Computer Programs

An IBM 360/50 computer was used to perform most

calculations, but a Univac 1108 Computer was used sometimes

in the final stages of structure refinement. The initi~l

plotting of structures was done using a Hewlett Packard

Recorder drivenby a Varian Data-6201 Computer with final

plotting done using a Calcomp Plotter driven by a XDS-Sigma

7 Computer.

The programs ACAC (30) and later ORABS (31) were used

to reduce the raw intensities to structure factors. The

program FAME (32) was used to calculate normalized structure

factors and output the Wilson plot and statistically analyze

for a center of symmetry. Direct methods were applied with

the program MULTAN (33) which determines phases derived

from E-values of FAME.

·The full-matrix, least-squares refinement was per­

formed using the program ORFLS (34). Calculation of Fourier,

20

difference Fourier and Patterson function maps was carried

out using the program ALFF (35). The program ORFFE (36)

was used to calculate interatomic distances, bond angles,

principal axes of thermal motion, and the standard errors of

the functions.

The program HYGEN (37) was used to generate positions

of hydrogen atoms from molecular geometry. The calculations

of bond distances and angles were routinely done using the

program JAM (38). The program BEPLA.l (39) was used for best

plane calculations. The crystal structure illustrations

were obtained using the program ORTEP (40).

Instrumentation

X-ray Diffraction

A Norelco X-ray generator made by Phillips Elec­

tronics Company, Mount Vernon, New York, was employed in all

preliminary film work. A Buerger precession camera made by

the Charles Supper Company, Natick, Massachusetts, was used

in preliminary examination of all crystals studied. Some

preliminary film data were collected with a non-integrating

Weissenberg camera also made by the Charles Supper Company.

21

Three-dimensional single-crystal X-ray diffraction

data were obtained on an ENRAF-NONIUS CAD-4 diffractometer

purchased from the ENRAF-NONIUS Company, Delft, Holland.

Ni-filtered copper radiation was used in data collection

for dicyclopentadienylscandium chloride and tricyclopenta­

dienylscandium. For magnesium indenide and trichlorotris­

(tetrahydrofuran)scandium a graphite monochromator with the

(002) plane in diffracting position was used to obtain

monochromatic Cu Ka radiation.

CHAPTER III

RESULTS AND DISCUSSION

Dicyclopentadienylscandium Chloride Dimer

At present the organometallic chemistry of scandium

is a relatively unexplored area. Tricyclopentadienylscandium

(41), triphenyl- and tri(phenylethynyl)scandium (7), and

dicyclopentadienylscandium chloride and derivatives have

been prepared, but no structural data have been presented.

The X-ray structure analysis of the dicyclopentadienyl­

scandium chloride dimer gives the first view of the stereo­

chemistry of an organoscandium complex and a study of the

nature of the scandium-carbon bond.

Yellow-green rod shaped crystals of dicyclopenta­

dienylscandium chloride were prepared by the method of

Coutts and Wailes ( 8)., and diffraction-quality crystals

were grown by slow sublimation. Preliminary unit cell

parameters were determined by precession (Cu Ka) photographs.

Systematic absences allow the space group to be P21/c. The

22

lattice parameters as determined from a least-squares

refinement of (sin0/A) 2 values for 12 reflections are:

0

a= 13.54(1) A

0

b = 16.00(1) A 0

c = 13.40(1) A

V = 2896 i 3

(3 = 93.97(5) 0

-3 The calculated density is 1.44 g cm for Z = 6.

23

Data were taken on an Enraf-Nonius CAD-4 diffractometer•with

Ni-filtered copper radiation. The crystal, a rod of dimen-

sions 0.17 x 0.17 x 0.42 mm, was aligned on the diffracto­

meter, such that no symmetry axis was coincident with the

~ axis of the diffractometer.

The diffracted intensities were collected by the

w-28 scan technique with a take-off angle of 1.5°. The

scan rate was variable and was determined by a fast

(20°/min) prescan. Calculated speeds based on the net

intensity gathered in the prescan ranged from 6 to 1° min-1 •

Background counts were collected for 25% of the total scan

tiine at ·each end of the scan range. For each intensity the

scan width was determined by the equation·

scan range= A+ B tane

24

where A= 1.0° and B = 0.5°. Aperture settings were deter-

mined in a like manner with A= 4 mm and B = 4 mm. The

crystal-to-source and crystal-to-detector distances were

21.6 and 20.8 cm, respectively. The lower level and upper

level discrimminators of the pulse height analyzer were set

to obtain a 95% window centered on the Cu Ka peak. As a

check on the stability of the diffractometer and the crystal,

two reflections, the (111) and the (002), were measured at

30-min intervals during data collection. No significant

variation in the references intensities was noticed.

The standard deviations of the intensities, o1

,

were estimated from the formula

OI = {[cN+(Tc/2TB)2

(Bl+B2)]+ (0.03)2

[cN+(Tc/2TB)2

(Bl+B2)]2}½

where CN is the counts collected during scan time Tc and B1

and B2

are background intensities, each collected during

the background time TB. One independent quadrant of data

was measured out to 20 = 110°. A total of 1680 reflections

were judged to be observed on the criterion that I>o1

.

The intensities were corrected in the usual manner

for Lorentz, polarization, and absorption (31) effects

-1 (µ = 85.5 cm ).

Fourier calculations were made with the ALFF (35)

program. The full-matrix, least squares refinement was

carried out using the Busing and Levy program ORFLS (34).

The function w(IF I-IF 1> 2 was minimized. No corrections 0 C ·

25

were made for extinction or anomalous dispersion. Neutral

atom scattering factors were taken from the compilations

of Ibers (42) for Sc, Cl, c, and H. Final bond distances,

angles, and errors were computed with the aid of the Busing,

Martin, and Levy ORFFE (36) program. The crystal structure

illustration was obtained with the program ORTEP (40).

Partial structure solution was accomplished by direct

methods, and an electron density map phased on the scandium

and chlorine atoms yielded the positions of the remaining

nonhydrogen atoms. Several cycles of least-squares refine­

ment with isotropic thermal parameters for all atoms produced

a reliability index of

R = r(IF 1-IFcl)/(EIF I>= 0.13 . 0 0

Conversion to anisotropic temperature factors, the inclusion

of hydrogen atoms in calculated positions, and additional

cycles of refinernent·produced a final R = 0.072 and

26

Unit weights were used at all stages of refinement, and no

systematic variation of w(IF I-IF 1>2

vs. IF I or (sin0)/A 0 C 0

was observed. The largest parameter shifts in the final

cycle of refinement were less than 0.10 of their estimated

standard deviations. A final difference Fourier map showed

no unaccounted electron density. Atomic and thermal para-

meters are given in Tables 4 and 5, respectively. Observed

and calculated structure factor amplitudes are listed in

Table 6.

In the unit cell there are six chlorine-bridged dimers,

of which four lie in general positions and two reside on a

center of symmetry. Although there are two crystallographi­

cally different molecules, they do not differ significantly

in any respect and the configuration in each case is repre-

sented by Figures 1 and 2. The cyclopentadienyl rings are

bonded in a penta-hapto-fashion, with the scandium-carbon 0

bond length (Table 7) ranging from 2.39 to 2.49 A, and 0

averaging 2.46 A. This value is somewhat shorter than the 0

2.49 A standard found in Sc(C5

H5

)3

(5), and could reflect

either the somewhat greater ability of the chlorine atom to

remove electron density from the scandium atom, or the more

crowded environment about the scandium atom in tricyclo­

pentadienylscandium.

27

TABLE 4

FINAL ATOMIC POSITIONAL PARAMETERS a,b O · · FR

· [<c5H5) 2scc1) 2

Atom x/a y/b z/c

Sc(l) 0.0520(1) 0.7352(1) 0 .34"88 (2) Sc(2) 0. 2511 (1) 0.8969(1) 0.4438(2) Sc(3) 0 .4134 (1) 0.4134(1) 0.4382(2) Cl(l) .0.2030(2) 0.8118(2) 0.2842(2) Cl(2) 0.0963(2) 0.8267(2) 0.5043(2) Cl (3) 0.4202(2) 0.5729(2) 0.4594(2) C(l) -0.0336(9) 0.8097(14) ·0.2066 (13) C(2) -0.0568(11) 0.8507(8) 0.2944(15) C (3) -0.1151(10) 0.7983(10) 0.3495(11) C(4) -0.1271(7) 0.7291(8) 0.2983(11) C(5) -0.0822(9) 0.7322(10) 0.2173(11) C(6) 0.0206(10) 0.5828(7) 0.3429(13) C (7) 0.0333(10) 0.6038(8) 0.4416(12) C (8) 0.1306(14) 0.6274(8) 0.461;3(13) C(9) 0.1750(9) 0 .6237 (8). 0.3735(16) C (10) 0.1076(15) 0.5969(9) 0.2980(11) C (1.1) 0.3347(9) 0.7838(9) 0.5415 (13) C(12) 0.3852(10) 0.7913(8) 0.4572(11) C(13) 0.4298(9) 0.8685(8) 0.4602(10) C (14) 0.4092(8) 0 .9076 (7) 0.5469(9) C(15) 0.3519(10) 0.8558(10) 0.5985(9) C(l6) 0.1363(11) 1.0009(10) 0.3770(22) C(17) 0.1630(16) 1.0269(9) 0.4700(19) C (18) 0.2560(15) 1.0480(8) 0.4834(13) C (19) 0.2919(10) 1.0389(7) 0.3899(13) C(20) 0.216(15) 1.0149 (8) 0. 3302 ( 11) C (21) 0.3736(11) 0.3424(9) 0.2750(10) C(22) 0.3728(10) 0.4270(11) 0.2576(9) C(23) 0.4709(13) 0.4534(9) 0.2754(10) C (24) 0.5252(10) 0.3849(10) 0.3055(10) C{25) 0.4669(14) 0.3190(9) 0.3074(12) C (26) 0.2865(22) 0 .3125 (15) 0.4771(17) C {27) 0.3537(13) 0.3076(11) 0.5526(16) C (28) 0.3554(11) 0.3784(15) 0.6016 (11) C{29) 0.2863(18) 0.4303(9) 0.5582(19) C(30) 0.2475(9) 0.3851(18) 0.4785(17) H(l) 0.0038 0.8420 0 .1621

Atom

H(2) H(3)

H ( 4) H(5) H(6) H (7)

H(8) H (9)

H(lO) H (11) H (12) H (13) H(l4) H(lS) H(l6) H(l 7) H (18) H(l9) H(20) H (21) H(22) H (23) H (24) H(25) H(26) H(27) H(28) H(29) H(30)

x/a

-0.0447 -0.1374 -0.1640 -0.0742 -0.0375 -0.0190

0.1641 0.2459 0.1173 0.2979 0.3899 0.4653 0.4306 0.3254 0.0734 0.1132 0.2949 0.3600 0.2236 0.3142 0.3210 0.4998 0.5997 0.4934 0.2599 0.3938 0.4019

· 0.2776 0 .1942

TABLE 4--Continued

y/b

. 0. 9059 0.8101 0.6805 0.6910 0.5608 0.5981 0.6468 0.6374 0.5906 0.7342 0.7466 0.8929 0.9616 0.8647 0.9846 1.0286 1.0637 1.0506 1.0067 0.3071 0.4662 0.5115 0.3864 0.2641 0.2782 0.2545 0.3849 0 .4 86 8 0. 4182

z/c

0.3211 0.4166 0.3156 0.1644 0.3094 · 0.4903 0.5227 0.3661 0.2251 0.5585 0.4094 0.4055 0.5675 0.6649 0.3550 0.5258 0.5476 0.3764

-o.2548 0.2706 0.2329 0.2713 0.3148 0. 32 86 0.4171 0.5581

·0.6608 0.5907 0.4415

a Standard deviations in parentheses refer to last digit quoted.

0 2 b Isotropic thermal parameters set at 4.0 A for all

hydrogen atoms.

28

29

TABLE 5

· . ab ANISOTROPIC TEMPERATURE FACTORS ' (x 104 )

FOR [cc5a5 ) 2scc1] 2

Atom 13 11 13 22 13 33 13 12 13 13 13 23

Sc (1) 35 (1) 30 (1) 67 (2) 2 (1) -19 (1) -5 {1)

Sc(2) 41(1) 30 (1) 58 (1) 2(1) -14 (1) -4 (1)

Sc (3) 36 (1) 35 (1) 55 (2) -2 (1) -21 (1) 4 (1)

Cl (1) 47(1) 49 (1) 51 (2) -1 (1) -5(2) · -9 (1)

Cl (2) 46(2) 47 (1) 59(2) -3 (1) -3 (2) -6 (1)

Cl (3) 35 (1) 37 (1) 69(2) 5 (1) -2 8 (1) 4 (1)

C (1) 43(9) 176(18) 113(16) 18(10) -15(9) 104(13)

C(2) 93(13) 35(7) 193(21) -4(7) -83(13) 18(10)

C (3) 73(10) 72(9) 116 (15) 32 (8) -35(9) -40(9)

C (4) 24(7) 75(9) 110(14) 4(6) -9(7) 7(9)

C(5) 59(10) 96 (11) 8 4 ( 14) 26 (8) -13 ( 8) -9(9)

C (6) 102 ( 11) 22(6) 164 ( 17) -9 (6) -71(11) -11 (7)

C(7) 94(11) 55(8) 127 (14) -7(7) 12(10) 15(9)

C (8) 159(17) 38(7) 123(16) 3 ( 8) -79 (12) 12 (8)

C(9) 60(9) 52 ( 8) 221(23) 15 (7) -44(12) 30 (11)

C(lO) 169(17) 56 ( 8) . 98 (14) 36(10) 11 (12) -8 ( 8)

C (11) 60(10) 65(9) 159(18) 0 -6°(10) 49(10)

C(12) 77(10) 40(7) 135(15) 35 (7) -54(9) -39 (8)

C (13) 72(9) 67 (8) 66(12) 3(7) -16(8) -10 ( 7)

C (14) 61 ( 8) 31(6) 84(12) -21 ( 6) -26 ( 7) 9 ( 6)

C (15) 96(11) 89(10) 37(10) 26 (8) -17(8) -2 (8)

C(l6) 66 ( 11) 43(9) 419(42) -5(9) -84(18) 51 (16)

C (17) 141(19) 33 ( 8) 303 (33) 9 ( 10) 126(20) 14(12)

Atom

C (18)

C (19)

C(20)

C {21)

C (22)

(2 3)

C(24)

C(25)

C (26)

C (27)

C (28)

C(29)

C ( 30)

191(19)

89 (10)

226 (21)

106(2)

107(12)

151 (15)

95 (12)

172(18)

249 (32)

123(16)

76(12)

187 (23)

3 8 ( 8)

30

TABLE 5--Continued

33 ( 7)

29(6)

43(7)

73(9)

108 (11)

60 ( 8)

91 ( 11)

52 (8)

110(16)

68 (11)

107(16)

139(16)

83(13)

6 3 ( 12)

37(11)

65(12)

77 (13)

105 (14)

8(10) -70(14) -18(8)

11(6) 14(10) 13(8)

-10{11) -100(14)

-24(8) -11(9)

5 4 ( 10)

. -13 (9)

33(9)

38(10)

8 { 8)

-26 { 8)

-1 {8)

-3 (7)

-36(9)

-19 ( 8)

148(25) -129(18)

-37(9)

7 (11)

5 (9)

-32 (10)

39(19)

40(13)

-33(15)

153(23) 51(11) 51 (11)

135 (16) 86 (14) -31 (11) -20 (10) 13 (13)

38(7) 211(27) -39(10) 139(19) -18(11)

166(19) 177(24) 4(12) -26(11) 98(17)

a Standard deviations in parentheses refer to last digit quoted.

~ Anisotropic thermal parameters defined by

2 2 2 exp [- Cf\1h +s 22k +s 33 1 +2s12hk+2s 13h1+2s 23kl]

31

TABLE 6

OBSERVED AND CALCULATED STRUCTURE FACTORS FOR THE DICYCLOPENTADIENYLSCANDIUM

CHLORIDE DIMER

1 O 1!,> 1>,2

2 on.• "•' l,; 11., "·' • o H,6 0,1 5 ., 1l,2 "·"

l iiUi

-tl: .. ;!;~.:tl

:1 111m im~ :~ i ·~m 'Wi

_,.

51,2 ,,., ,i,, •5,1

10., 10 ••

20,. "·' l~. l '"•• JO,• l1,S

52,1 S•,l a,, ,.,,

H,1 27,6

20 •• 15,J

1s,1 n.o S>,8 55,0 1", I l,6 16,1 72,1

18.J 21.0

"·' "·' 2•-· 10., 07,C 10,9

;,,o 22,S

10l,71Gl,l

n,o lS.S ., •• ,s,s

39,J 16,S ... , .,.~ ·~-· u., -,o u., .... 16.l 100 1 n.2 ;io,s

_,

22 ..... . s, ..... . ~., n,l .... ...9 , •• , 11,0

l!.t JJ,2 a.• n.s

22.c n.~ ,s.e 21,,

11.1 n.2 2,.2 n.1

22,J 2,.0

0(,0 ••••

20.1 2s,,

o.s n., 36,J H,l 02,7 .,., n.2 u.1 , •• , ,s.s

•12 2,.1 26,1 •1l l!,8 22,8

0 27,8 H.6 16,'l 1il.1

ss.2 , •. -, ••• s 01., n,, ••••

u.c· u,s ,,,r •••• J?,;, JJ,S 2!,6 21.,

B,.:; 1ij,1

.,.s ••. ,

n.s 1~.t 00,1 P.S,C· ., ... ,., l!,8 ,i., ,1., ;i .•

!l, I ~•-2 2!,> H,1 H,1 1",7

,,., n.• :19,S ;o,6 19.~ l!,s l~,S 2".v 1, .• 1J.• 1',> l8.~ H,S 17,! ~,.' !J,J

l•,( 25,) ,, •• 28 •• 2,., 25,7 18,• 1l,l

"·' 11,5

S 1,,e J•.• ,:., l),5

'"·' 15,S u.• "·"

I : "•• ll,• -l 015,,lHl,O , , n,, ,,.,, -l O '"•' ,o,s

, C11J,ll1>,0

o 1 10,, 10,? -1 7 2 ••• 21, l

' 1 '"·' ,s,; f 7 "·' 1',5 1 1 "·' ,,1 " • ,,., ,,. 1 1 • Jt.,. ,,,;

-i 8 SJ,J101,S , ",,., , ... -l • .2l.l 22,• ] ";!., "·' • I n,1 ,s,; ! ~ Ji, l .1,, a

•• a ll,7 ll,l • ".,,t ,,.s -1 a ,,.c .s,s 1 _, ,,.1 1,., -2 •• , ••• 6,2

l 9 5Q,1 !1,0 1 • 17,5 15,5

-• o "•' oo,l ! • i1,o ll,• , 1 n.i 11,1 t 10 H,J H,S

-1 1~ oE.l s,.1 1-10 "·' 10,J

-l lJ O,! !t,O l•10 1S,6 11,1

• 1, , .... 26,< 11 1' "·' ,1,,

1 1l lt,b s,> -• 11 ,1,r, 11,\

, 11 lo,5 lS,l -l II"•' ,5,;

J 11 , ••• ,,·,,

S II ll,l !•,s

• " '"·' 17,)

9 11 .... 11,0 -1 "v., )!., _, 1l ,, •• 1),1

> l2 "·· 1i,;

• I.! .!l.l 20,'; , 1l 2',1 1',l

-0 ll .-.• •l,2 6 l2 ll,l l!,9

•1 1l i,.'I ll,l 1 l2 i,.1 !6.1

-~ !l. "'·' ,, •• ., "••·• n,.

1 1J ;,,1 "·' i 1l lJ,9 l<,7 j ,1 i,,, "1,)

·• 1l "·· '7,7 ! 1l 2•.J H.I • 1J 11.1 "·'

•7 1l 32,1 l!.8 o 11 n,; ,..,

., 10 10,2 11,, 1 , •••••• ,.;

-2 1• 22,< lS,S -l 1• 21,S lS,S

o 1' .S,O ll,1 •SU 1',.< l1,0 s 1• u,, 11,0

l !l~l I l 21.0 i1.•

-7 l ll,2 2S,O 7 l 20.0 •••• • J 2, ...... 9 l 21,! il,i

-11 l :11.• 21,1 '1 l 20,l 1J,6

-1• J 19.6 11,7 r • ,i.2 ••·•

-1 • 11,t H.l 1 O 37,l ll,9

-• • , •• 7 ... ~ -J • 91,l It,•

l • 8~. 1 O~.S -• • ,2.8 ., •• ..... , "'·' -s, 02,s 01,1

5 • ,t.• lO,O 6 • l7,• l7,l

•1 • 1s,o l1,S 1 • ,,., ,,.,

-9 • :il.o H.~ ., s •••• H,1

1 ! •5.( .... -2 , ,,,.r 1n.,

2 ~ 10.1 "·' -:i i !1,1 ss.i

1 5 1,1., ""·· • ! 1CS. l 1~ 1, • S S 19,0 17,6

•• ! n,, H.a • S JS. l •~.S 7 s 21,! 10,l

_, S '"·' 7',7 • ~ ,., 'I .,. 'i C • 11,1 12,o 1 • ... , .,.1 _, •• ,.1 .,., i 6 ll,0 ,,,2

-l • •S,' ••.1 J fl!,, ll,a

•• • H,9 10,2 •• "'·' BJ,1

·• '1',1 •1.1 i , '"•' n.~ •• • n,• 01,1 6 O JC.7 41,l

-1 7 ""·' •1.~ ' 1 ••••• , •• ~ l 21.l 27.5

'-l 710f.< IC1.I l 7 !l.• 11,•

-· 7 11,2 17,7 • , ,;1.0 ,a.1 5 1 !1,5 ,, ••

·• 1 JC,1 , •••

-1 1 lJ,l 11,9 7 7 ,.,. 21.,

~ " 7",6 "-~ •1 • 11,7 18,.

I • 6C,l H,0 •l S Ol,2 Ol,l

1 a 11,1 "·· •• .,,, 12,1 •~ a >1, g ll,9

S 8 It,! 15,2 -• , "·' 16,5 ' , "•' n,1

-1 6 lf,O n,J ' • ,, •• J.:.J _, • ,, .• ,.,6 ' • I!,< ,., _, • ss., "·" l 9 H,.! 11,l

1-11111

1'),J ....

28.1 12,2

<!,i .,.,

18,! "·' 0,,1 "·" .,., .,,.

H,1 11,• i,., .,,,,, .,.s "·· H,< •••'

l9,t n,,

2',S ll,5

.,., , .. , <!,, ....

,,., "·'

ie., 2•.1

,,_. "·" ,c,,1,a,.,

57,S 61,1

,.,6 17,S 19,~ 16,·l •••• H.a ;1,1 "·'

., ... , .. ,o.o ,~ ••• , .. , "'·' 111.,,11.1 ,s,, ,.,,

H,6 n.a 01,2 ,a.•

-· '2,2 11., l0,7 ll,8 , ... ,,,. '"·" 11,7

!2,1 !1,l

,,., "·' l!.1 Jl,a

"·' 2{,; "•' n.s

"·' 10., ii., ,,. ,

"·· )1,1

,,., ,.,\

"·" , .. , -l 1s,s 1:.1 ,s., ,, .•

'"·' ,.,;

.,.1 -",1 "•• JC,l

J~, 7 Jl,S

-1r ,1., .,,,i

"" Vi., ,1., ,,., 1,,o 11,S

11,, e,l

-• "·' i1., 11,1 ,,;.,

:j H:l ~U ,.,. J•.• '"•' n., 22,! ... ~ ;10,( ,s,1

',. ....... , ·• ,. ,,., ,s.,

; ! "1•• H,•

• 1 >),'; "·'

-, 1 1!,l ll,•

1'. I '7,< 11,l < ' .... 11.,

·l l 11,e 11,i

-: 1 lU Hil I l !l,8 !1,•

a< !O,l ••••

l1 l ·••• lv.1 -11 l 18 •• 22,•

• l 61,t !a,1 •S l i,,] 27,S

•1 l 1',C Z•,l 7 l '7,1 l9,(,

·• • o .• 51,. ..... , ,, .. •• • .,,, •o,5

11 • "·· "·"

-1 , ,~., :ii.o

< ; H.! 7'.7 ·l s,s,,e1s,,•

1 s u,2 JS,5 o s Jl,1 "••

11 • ,,.1 ....

' . "·" ,._., 1 • JS,( JS.l

g • '"·" 21,2 11 • n,1 ,i.o ,, . "·' ... ,

l 7 •••• "1,o -l 7 o,,l Jg,2

l 7 ,e,1 <S,l -• 1 6l,<· <J.~

0 1 .,., 67,0

5 1 ,.,, 11,1 • 1 , •• 1 , •• J

1 1 "" 10,', -• 1 ,.,. 18,1

-• 1 , •• , )1.2 9 l S6,7 !i,l

_,, 1 , ••• .,_.

,, 1 n.~ 11.• -11 7 '1,2 11,l

~ e ,e. ! ••·• 1 a,,,. ,s.,

fl l!i! lll! 11 • 17,l 1l,•

-11 a 41,l ••• I • l!,1 20,2 ., ..... ,;., ' '.!1'.) J,t,J , • n.a ,~.c

-s '"·" "·' ! .... , .,.; • • 2'.U H,l

-1 • ;,,, ,,.,

-s , ll.l, <•,J , 1( .... 18,1

·l lC· H,• ll.1 2 1, .• ,.; ••• ,

•l 10 18,S 1),l

""" ,i,, ,, •• -• ,, ,i,, , •.•

" 1~ "· ! "'·' 10 1, 1J,l J<;,o ., 11 ,,., ,.1

l 11 19,7 s,1 ·\ 11 !•,1 11., ',, '1,1 "·· o 11 10,J 1',l S 11 ,, •• 1",l . " .... '"·' -~ " "·, ,r. 1 • 11 Jo.l l',)

-s 11 1;,, t<.l a 11 J•,J JS,'!

-11 11 n.,: "·' ·I» ,e,, ,s,,; 1 1l H,' 3",7

-2 1l lJ,< !i,J ' ,, ,s,; ,~.; l 1l l!,O 2;.1

• ,, «,1 "'·' -, 12 ... , 1, •• o 12 i,,, 31,)

-1 1~ 1°, ( 10,• 7 !l 1s.• 15,)

"1l "·' "·' _, 1J "·" 1',2 1 ,; ll,• 1l,•

•l 1l ll., "•" < 1J Of,; •5,l

-• 1l •1., ••.~

• 1J "·" "·' -~ 1l ta," 1i,S -• IJ u.c 7,2 -• u '"·' 11,,

7 11 Jl,i '"·" 0 1, •••• ·~- 1 1 10 17,1 ....

t11Jl{!!:!

-1 1 17.t J6.5

2 1 '"·' u., •l 1 •>,7 0,l l 1 U.• U,l

., 1 !1,1 se,2

-• 1 Si,! S<.J l I <•.7 2',D

;i H ff! in l 10 17.1 10,7

:((ii:i"iiii :i ! n] ;n -· ) , •• ! ,, ••

-: ~ !~:f :1:~ •• O 1,.1 J.,D

1 O !l.• i:i.2

-: f !t~ !~:! _, \ 1,., Ja,8 10 ( l0,1 2',7

-•i ~ i!:i iti , 1 1•.s ll,O

., 1 1•.• n.2

-! l H:i UJ • , /!,! ,.,.

., 1 J~., ., .• 1l 1 <8,0 JS,O

-;~ l HJ H:! 1 < 1•.a ll,1

-; i ~ti !~:~ .l ~ ~!:! ~!:t

q I J8,S l8,0 -• 2 ••• , ,1.,

32

• l Ji.8 U,S

l l JC,J l0.1 •8 l >6,t "•'

•9 l H,l 11,I

•! l 19,1 S,J

•1 l 16,9 ll,9 •& J 21,l 10.6

t l 14,1 79,0

1 • l0,7 11,0 -• • 10.s 1a.2

2 • 26,5 11.• -• .... , ,s.o

-1 • ••·• n,a

1 • n.• ,u.2 a• 1S.9 16,S

~ ; :::} :;:: • S ll,l 30.S

1 6 .,,, 0,5 -1 • .,., 16.8

l • E,! ••• -l • 10,c 15.5

l • 12,• lt,6

: : :::: :i1 ·• o 25.3 2::~

-; l 11,1 ll,0

•9 1 21.l l2,5 -1 • s1.s 50.J

2 8 "9.2 u.o • o 1',1 lt,l

-• • 17,0 11.1

-• g "·' 11,6 -• • 10.1 18,8

-2 10 >•·• n.1 l 10 11,1 lt,5 s W , •• ~ 22 ••

-• ,o ]9,6 )6,5

Q 11 2•,7 11,l 1 11 22.:,, .~ ••

-1 11 23,8 22,5 -2 11 2s.c 15,1 -• n 2s.• 22.6 -1 " n., 11.0

1 11 2, •• 25,5 _, 12 ,,,, ,,,,

-~ ll 21.2 2•.2 J 1l 2•.9 22.,

.; n n.• n,2 •S 1l 11.• U,6

OHOHL• ••••u•• 0 1 20,2 .... l 1 H,2 oe,J

-2 t :il,f 21,S -• t J6,6 ... , o 2 n.1 2•••

1iH

33

Fig. !.--Molecular structure of the dicyclopenta­dienylscandium dimer which lies in a general position in the unit cell.

34

35

Fig. 2. --Moleculat··str"u_ct6r.$ .. O·f the dicyclopenta­dienylscandium dimer which ·iies ··dn a center of symmetry in the unit cell.

TABLE 7

0

INTERATOMIC DISTANCES (A) AND ANGLES (DEG)

FOR ~C5H5)2scc1]2

Sc(l)-Cl(l) Sc(l)-Cl(2) Sc(2)-Cl(l) Sc(2)-Cl(2) Sc (3)-Cl (3) Sc ( 3) -Cl ( 4)

Sc(4)-Cl(3} Sc(4)-C1(4) Sc(l)-C(l) Sc(l)-C{2) Sc(l)-C{3) Sc(l)-C(4) Sc (1) -C (5) Sc ( 1) -C ( 6) . Sc (1) -C ( 7)

Sc ( 1) -C ( 8)

Sc(l)-C(19) Sc(l)-C(l0) Sc (2)-C(ll) SC ( 2) -C ( 12) Sc (2)-C(l3) Sc ( 2 ) -C ( 14 ) Sc(2)-C(l5) Sc(2)-C(l6) Sc(2)-C(17) $ C ( 2 ) -C ( 18 ) Sc(2)-C(19) Sc(2)-C(20) Sc(3)-C(21) Sc(3)-C(22) Sc ( 3) -C ( 2 3) .

Sc (3) -C (24)

Sc ( 3) -C (25) Sc(3)-C(26) Sc(3)-C(27) Sc (3)-C (28)

2.585(4) 2.583(4) 2.580(4) 2.559(4) 2.568(4) 2.565(4) 2.565(4) 2.569(4) 2.47(1} 2.44(1) 2.48(1) 2.47(1) 2.44(1) 2.48(1) 2.46(1) 2.48(1) 2.45(1) 2.45(1) 2.46 (1) 2.48(1) 2.46(1) 2.47(1) 2.48(1) 2.41(1) 2.44(1) 2.48(1) 2.46 (1) 2.45 (1)

2.49(1) 2.45(1) 2.45(1) 2.46(1) 2.46(1) 2.44(1) 2.46(1) 2.44(1)

Bonded

C(l)-C(2) C(2)-C(3) C ( 3) -C ( 4)

C ( 4) -C ( 5)

C(5)-C(l) C{6)-C(7) C (7)-C (8)

C(8)-C(9) C (9) -C (10) C(10)-C{6) C {11) -C (12) C ( 12 ) -c ( 13 ) C (13) -C (14) C(14)-C(l5) C(15)-C(ll) C(l6)-C(l7) C(l7)-C(l8) C(l8)-C(l9) C(l9)-C(20) C ( 2 0 ) -C ( 16 ) C(21)-C(22) C (22)-C (23) C(23)-C(24) C (24) -C (25) C (25) -C (21) C(26)-C(27) C ( 2 7 ) -c ( 2 8 )

C ( 2 8 ) -C ( 2 9 ) C(29)-C(30) C(30)-C{26)

37

1.40(2) 1.40(2) 1.31(2) 1.28(2) 1.41(2) 1.36(2} 1.38(2) 1.36(2) 1.38(2) 1.38(2) 1.37(2) 1.37(2) 1.36 (2)

1.37(2) 1.39 {2)

1.34(2) 1.30(2) 1.38(2) 1.31(2) 1.31(2) 1.38(2) 1.40 (2)

1. 36 ( 2) 1. 32 (2)

1.36(2) 1. 32 (2)

1.31(2) 1.35(2) 1.37(2) 1.38(2)

TABLE 7--Continued

Bonded

Sc(3)-C(29) Sc(3)-C(30)

2.45(1) 2.39(1)

0

Nonbonded Distances (A)

C (5) -c (6)

C (5) -C (10) C(4)-C(10) C(4)-C(6} C(3}-C(6} C(ll)-C(9} C(14)-C(17) C(14}-C(19} C(13)-C(19) C(21)-C(26} C (21} -C (30}

C (22)-C (30) C(25)-C(27)

3.19(2) 3.48(2) 3.82(2} 3.11(2) 3.91(2) 3.95(2) 3.92(2} 3.30(2) 3.40(2) 3.06(2) 3.38(3} 3.57(2} 3.73(3)

C (5) -C ( 7) C(2)-C(16} C(4)-C(7} C(3)-C(7} C (11) -C (8)

C(l5)-C(l8} C(14}-C(18} C (13) -C (18} C(8}-C(29} C ( 21) -C ( 2 7 ) C(22)-C(26) C{25)-C(26)

Bond Angles

Sc{l}-Cl(l}-Sc(2) Sc(l)-S1(2)-Sc(2) Cl (1) -Sc (1) -Cl-(2) Cl(l)-Sc(2}-C1(2} C1(3)-Sc(4)-C1(4) Sc{3)-Cl(3)-Sc(4) C{l)-C(6)-C(7) C(6)-C(7)-C(8) C{7)-C(8)-C(9) C { 8) -C ( 9) -C ( 10} C{9)-C(10)-C(6} C{20)-C(16)-C(17) C{16)-C(17}-C(l8) C{17)-C(l8)-C(l9) C(18)-C(l9)-C(20) C(19)-C(20)-C(16) C(30)-C(26)-C(27) C(26)-C(27)-C(28) C(28)-C(29}-C(30)

97.6(1) 98.2(1) 81.8(1} 82.3(1} 80.4(1) 99_.6(1)

109.3(12} 107.9(14} 107.2(13} 109.8(14} 105.8(14) 102.3(13} 113.8(17) 104.2(14) 106.0(14) 113.2(17) 108.1(16) 108.8(15) 103.3(1.4)

C(2}-C(l)-C(S) C(l)-C(2)-C(3) C(2)-C(3)-C(4) C(3)-C(4)-C(5) Sc(3)-Cl(4)-Sc(4) Cl(3)-Sc(3)-C1(4) C(l)-C(5)-C(4) C(15)-C(ll)-C(12) C(ll)-C(12)-C(13) C(12)-C(13)-C(14) C(13}-C(14)-C(15} C(l4)-C(15)-C(ll} C(25)-C(21)-C(22) C(21)-C(22)-C(23) C(22)-C(23)-C(24) C(23)-C(24)-C(25) C(24)-C(25)-C(21) C(27)-C(28)-C(29) C(29)-C(30)-C(26)

38

3.88(2} 3.67(2) 3.44(2) 3.86(2) 3.83(2) 3.64(2) 3.14(2) 3.74(2) 3.96(3) 3.79(2) · 3.72(3) 3.45(3)

101.1(12) 109.3(12) 106.5(14) 111.3(14) 99.6(1) 80.4(1)

111. 8 (14) 108.3(12) 107.3(12) 108.8(12) 108.2(11) 107.4(12) 108.7(13) 105.8(11) 107.1(13) 109.7(14) 108.6 (14) 109.1(15) 110.7(15)

39

0

If one takes 0.68 A as the radius (4~6} of the

scandium(III} ion, a scandium-carbon bond length of 2.46-2.49

0

A in dicyclopentadienylscandium chloride agrees very well

with the value predicted on the basis of the two known

organosamarium structures. The average samarium-carbon bond

0 0

distance is 2.78 A in (C5

H5

) 3

sm (43) and 2.75 A in

(c9

H7

)3

sm (44); the generally accepted radius of the

0

samarium (III} ion is 0.96 A (45).

0

The scandium-chlorine distance of 2.575 A is quite

0

long compared to that found in Scc13

(c4

H8

o}3

(2.413 A) (46}.

However, the structure of the latter consists of discrete

molecules in which each chlorine atom is bonded to only

one scandium atom. The lengthening of a bond to a bridging

halide ion is quite common: in [CH3AlC1

2]

2 where there are

both bridging and terminal chlorine atoms, the bond lengths

0

are 2.25 and 2.05 A, respectively (47).

As is shown in Table 8, the scandium atom lies on the

0

average 2.18 A out of the plane of the cyclopentadienyl

groups. Within rings themselves, the bond distance and

angle are normal.

The packing is typical of a molecular compound:

0

the shortest nonbonded contacts are 3.1 A between carbon

40

atoms on cyclopentadienyl groups bo~ded to the same scandium

atom, and the closest inter-molecular carbon-carbon approach

0

is 3.82 A.

Plane

Scl Ring 1

Scl Ring 2

Sc2 Ring 1

Sc2 Ring 2

Sc3 Ring 1

Sc3 Ring 2

Atom

Cl

C2

C3

C4

cs Scl

Atom

Cll

Cl2

Cl3

TABLE 8

BEST WEIGHTED LEAST-SQUARES PLANES FOR [cc5H5 ) 2sccl] 2

-0.7892x + 0.3790y - 0.4832z - 4.0900

-0.2495x + 0.9472y - 0.2015z - 7.9333

-0.7792x + 0.4130y - 0.4715z + 1.4367

-0.2428x + 0.9465y - 0.2123z -13.7549

0.2436x - 0.1898y - 0.95llz + 3.3665

0.72llx + 0.3712y - 0.5849z - 0.6561

D

Deviations of atoms from planes (A)

=

= = = =

Scl Ring 1 Atom Scl Ring

-o.oo C6 -0.01

-0.00 C7 0.01

o.oo ca 0.01

o.oo C9 -o.oo -0.00 Cl0 -o.oo -2.19 Scl 2.17

Sc2 Ring 1 Atom Sc2 Ring

0.01. Cl6 -0.03

· -0. 01 Cl7 0.02

-0.00 Cl8 0.03

0

0

0

0

0

0

2

2

41

TABLE 8--Continued

Atom Sc2 Ring 1 Atom Sc2 Ring 2

Cl4 o.oo Cl9 -o.oo Cl5 o.oo C20 ·-0.01

Sc2 2.20 Sc2 -2.17

Atom Sc3 Ring 1 At.om Sc3 Ring 2

C21 0.01 C26 -0.00

C22 -0.01 C27 -0.01

C23 o.oo C28 0.00

C24 -0.01 C29 -0.00

C25 0.01 C30 0.01

Sc3 -2.17 Sc3 2.18

Tricyclopentadienylscandium

Birmingham and Wilkinson (41) first predicted the

bonding in Sc(C5H5) 3 to be purely ionic on the basis of

chemical reactivity and solubility measurements. More

recently, Nugent, et al., (48), have determined from absorp­

tion and uv-excited emission spectra that the percent covalent

character in the tricyclopentadienyllanthanides is not

greater than 2.5%. In opposition to this view stands the

work of Wong, Lee, and Lee (43) on the crystal structure of

Sm(C5H5) 3 . Even though their calculation (from the observed

bond lengths) of only 37% partial ionic character in the

42

samarium-carbon bonds- is at best questionable, the fact that

the cyclopentadienyl rings have a definite preferred orien­

tation may be interpreted as structural evidence for some

covalency in the metal-carbon bonds. · It has been painted

t (2) h . . f h 11 . . d" f 3+ ou tat in view o t e sma er ionic ra ius o Sc

l . 3+ ( ) . . re ative to Sm , Sc c5H5 3 may be expected to exhibit con-

siderable covalent character.

The crystal structure of tricyclopentadienylscandium

gives the first direct evidence for a.degree of covalency in

the scandium-carbon bond.

Tricyclopentadienylscandium was prepared by the

sealed-tube reaction of dicyclopentadienylrnagnesium with

scandium trifluoride (29). Single crystals of Sc(C5H5) 3

were gro~n by_ sublimation and sealed in thin-walled glass

capillaries •.

Preliminary unit cell parameters were determined by

precession (Cu Ket) photographs. The crystal system is

orthorhombic. Systematic absences allow the space group to

be Pbcm or Pbc21 • The lattice parameters as determined

from a least-squares refinement of (sin0/~) 2 values of 12

reflections are

43

0

a = 12.881(5) .A

0

b = 8.954(4) A

0

C = 9.925(4) A

V = 1145 i. 3

-3 the calculated density is 1.41 g cm· for Z = 4 using the

standard relation

N =

M =

D =

V =

Data were taken on

NM= -24

D XV X 10

l.66 x 10-24

number of molecules

molecular weight

density

volume of unit cell

per unit cell

(~3)

an Enraf-Nonius CAD-4 diffractometer with

Ni-filtered copper radiation. The crystal, a rod of dimen­

sions 0.12 x 0.15 x 0.70 mm, was aligned on the diffracto­

meter, such that the rod axis was coincident with the axis

of the diffractometer.

The diffracted intensities were collected by the

scan technique with a takeoff angle of 1.5°. The scan rate

-1 was variable and was determined by a fast (20° min ) pre-

scan. Calculated speeds based on the net intensity gathered

-1 in the prescan ranged from 7 to 0.8° min • Background

counts were collected for 25% of the total scan time at

each end of the scan range. For each intensity the .scan

width was determined by the equation

scan range= A+ B tane

where A= 0.9° and B = 0.45°. Aperture settings were

determined in a like manner with A= 3 mm and B = 3 mm.

44

The crystal-to-source and crystal-to-detector distances were

21.6 and 20.8 cm, respectively. The lower level and upper

level discriminators of the pulse height analyzer were set··

to obtain a 95% window centered on the Cu Ka peak. As a

check on.the stability of the diffractometer and the crystal,

one reflection, the (121), was measured at 30-min intervals

during data collection. No significant variation in the

reference intensity was noticed.

The standard deviations of the intensities, cr, were I

estimated from the formula

a I = {[ CN + (Tc/2TB) 2 (Bl+B2)] + (O .03) 2 [cN +Tc/2TB ,2 (Bl +B2)] 2 }'·

where CN is the counts collected during scan time Tc and B1

and B2 are background intensities, each collected during

the background time TB. Two symmetry related octants were

measured out to 20 = 100° and one octant to 20 = 150°. A

45

total of 1620 reflections was collected of which 1013 were

unique and had intensities greater than background.

The intensities were then corrected for Lorentz,

. -1 polarization, -and. absorption ( 31) effects (µ = 53. 4 cm ) •

The calculated transmission factors ranged from 0.38 to

0.51.

Fourier calculations were made with the ALFF program

(35). The full-matrix, least-squares refinement was carried

out using the Busing and Levy program ORFLS (34). The

function w ( IF 1-1 F I ) 2 was minimized. No corrections were 0 C

made for extinction or anomalous dispersion. Neutral atom

scattering factors were taken from the compilations of

Ibers (42) for Sc, C, and H. Final bond distances, angles,

ahd errors were computed with the aid of the Busing, Martin,

and Levy, ORFFE program (36). Crystal structure illustra­

tions were obtained with the program ORTEP (40).

Preliminary density calculations indicated the pres-

ence of four molecules of Sc(c5tt5) 3 in the unit cell. This

was interpreted to mean that the scandium atoms must lie on

special positions in space group Pbcm or in general positions

in the acentric Pbc21 . The Patterson map clearly showed

the presence of the metal atoms on or near Z = 1/4, 3/4, the

46

location of the mirror planes in Pbcm. A structure factor

calculation based on the centric space group yielded an R

fact?r of- 38%, but the corresponding Fourier map was complex.

Many attempts at positioning cyclopentadienyl carbon atoms

with both ordered and disordered models did not improve the

R factor to below 33%. At this point the structure solution

was sought in the acentric space group Pbc21 . Fourier maps

phased on the scandium atom quickly revealed the coordinates

of several carbon atoms, and several electron density maps

preceded by partial least~squares refinement showed all the

non-hydrogen atoms in the asymmetric unit. The final

positions of the carbon atoms clearly show that the molecular

grouping cannot contain the mirror plane demanded by space

group Pbcm. Although the standard acentric space group is

Pca21 , the structure reported here is based on Pbc2 1 to

emphasize the similarity with tricyclopentadienylsamarium.

Subsequent isotropic refinement led to a discrepancy factor

of

Rl = [E(IF I-IF 1)/EIF ll X 100 = 9.6% 0 C 0

Anisotropic refinement lovered R1 to 7.1%. The inclusion of

0

hydrogen atom contributions at calculated positions 0.95 A

from the corresponding carbon atoms followed by further

47

anisotropic refinement of all non-hydrogen atoms led to a

final Rl = 4.1% and

R2 = [ Ew ( I F0 1-1 F O I i2 / (wF 0 ) 2 ] ½ x 100 = 4. 3%

2 wher~ w = 1/cr • Unobserved reflections and two reflectionsr

the {200) and (111) r whi.ch appeared to suffer from extinc­

tion, were not included. The largest parameter shifts in

the final cycle or refinement were less than 0.02 of their

estimated standard deviations. A final difference Fourier

03 map showed no feature greater than 0.4 e/A. The standard

deviation of an observation of unit weight was 2.39. No

systematic variation of w(IF I-IF 1> 2 vs. IF I or (sin0)/A 0 C 0

was observed. The final values of the positional and

t~ermal parameters are given in Tables 9 and 10, respectively.

Observed and calculated structure factor amplitudes are

liste4 in Table 11.

The most striking feature of the structure of tri­

cyclopentadienyls·candium is the existence of both bridging

and terminal cyclopentadienyl groups (Figure 3). Each

scandium atom is thus coordinated to two c5H5 . ions in a

penta-hapto- fashion and to two others through essentially

48

TABLE 9.

F-INAL ATOMIC POSITIONAL PARAMETERS· a,b' FOR TRICYCLOPENTADIENYLSCANDIUM

Atom x/a y/b z/c

Sc. 0.2514(1.) 0.4617(1) 0 .2400 (1) . C (1.) 0. 4367 (14) o .• 4632 (7) 0.1568(7) C(2) 0.4379(5) 0.5172(9)" 0.2862(9) C(3) 0.3853(6) 0.6501(9) 0.2937(9) C (4) 0.349"5(5) 0.6809(6) 0.1616 (9) C(5) 0.3826(4) 0.5647(6) 0.0792(6) C(6) 0.1359(4) 0.5495(7) 0.4227(7) C (7) 0.0819(4) 0.4362(6) 0.3551(7) C(8) 0.0571(4) 0~4868(6) 0.2197(8) C(9) 0.0982(4) 0.6321(6) 0. 2110 (6)

C(lO) 0.1446(4) 0.6697(7) 0.3362(8) C(ll) 0.2047(4) 0.2057(5) 0.5453(5) C(l2) 0.2934(3) 0.2770(5) 0.4887(6) C (13) 0.3121(4) 0.2167(5) 0.3627(5) C(l4) 0.2343(4) 0.1061(5) 0.3388(5) C(15) 0.1689 (4) 0.1025(6) 0.4466(5) H (Cl) 0. 469.3 0.3718 0.1226 H("C2) 0.4712 0.4710 0.3624 H(C3) 0.3747 0.7161 0.3719 H(C4) 0.3075 0.7646 0.1287 H(C5) 0.3700 0.5554 -0.0143 H(C6) 0.1631 0.5442 0.5160 H (C7) 0.0605 0.3409 0.3919 H (C8) 0.0236 0.4323 0.1471 H(C9) 0.0956 0.6974 0.1330 H(ClO) 0.1770 0.7669 0.3551 H (Cll) 0.1756 0.2246 0.6305 H (C12) 0.3313 0.3547 0.5331 H (Cl.3) o. 36A9 0.2478 0.2997 H(Cl4) 0.2295 0.0432 0.2620 H{Cl5) 0.1141 0.0390 0.4551

a Standard deviations - in parentheses refer to last digit quoted.

b Isotropic thermal parameters for hydrogen atoms taken - 02 as 4. O A .

49

TABLE 10

· a b 4 ANISOTROPIC TEMPERATURE FACTORS. ' (x 10. )

FOR TRICYCLOPENTADIENYLSCANDIUM

Atom 611 e22 e33 al2 e·13 e23

Sc 23 (.1) 56 (1) 47 (1) -1(1) 4 (1) -4 (1)

C (1) 25 (3) 105(7) 100(8) -4(4) 5 ( 4) 4 (7)

C(2) 4 7 (4) 204 ( 14) 133(10) -50(6) -35 (5) 71(10)

C (3) 62(5) 166(12) 144(9) -61 (6) 35 (5) -74(9)

C (4) 56(4) 69(6) 150(9) -10(4) 25(5) -11(7)

C(5) 39 (3) 117 ( 8) 73(6) -17(4) 11 (3) 4.(5)

C (6) 47(4) 119 (7) 86 (6) 15 (5) 10(5) -14(9)

C(7) 29 ( 3) 105(7) 89(7) 16 (4) 12 (4) 11(6)

C (8) 30(2) 105(6) 65 (7) 10 (3) 5 (4) 5 (6)

C(9} 53 ( 3) 90(9) 82 (7) 30(4) 11 (4) 9 (7)

C(l0} 56 (3) 94 ( 8) 12 7 ( 7) 10 (4) 18 (4) -45(6}

C (11) 45 ( 3} 81 (8) 46(8l -6 (4) -4 (4) 13 (7)

c.(12) 37(4) 80(6) 72(6) 5 (3) -8 (3) 32 (4)

C (13) 55 (3) 102(9) 50 ( 8) 8(4) 6 (5) 27 (7)

C (14) 6 8 (4) 86(6) 56(5) 2 (4) -10(4) 8(5)

C (15) 49 ( 3) 102(7) 49(5) -10(3) -9 (3) 14(4)

a Standard deviations in parentheses refer to last digit - quoted.

b Anisotr~pic the2mal par~meters defined by exp [-<ellh + e22k + B331 + 2a12hk + 2Bl3hl + 2B23k1)] .

50

TABLE 11

OBSERVED AND CALCULATED STRUCTURE FACTOR AMPLITUDES FOR TRICYCLOPENTADIENYLSCANDIUM

... •••11•on••••• 1 0 ,.s •.• : : ,t: ::~ 5 0 11,l J,, 6 O 65,7 H,1 ; ~ 2::: 2~::

10 fl J1,l H,6 11 0 ,.s 11,J 12 o ,,., n,1 16 0 21,1 22,5

, 2 u., n.o a 2 21.s 21.2 J 2 H,O 3',l s 2 21.2 .iz,1 , z u., n,1 , z 11,1 n.e I 2 H,!I J6,7 9 2 10,1 10.,

'Kl 2 fl!i,9 '5,2 t1 ,I 1C,l 10,1 12 Z 31,0 J0,1 12 2 11,6 J0,7

~ : .n:; :::: lil II !1,1 !1,5 l 'I $,9 !l,11 11 11 IC,5 H,J 5 I 21,1 H,Z •• u., o,o 1 \ 10,1 , •• I • 21,1 2,., 9 II 11,1 11,1

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1 1 "'·' •o.o 4 1 11.e 11,0 5 1 n.c 12,1 6 1 24,5 2',1 1 1 u.2 •s., 9 1 1a.o 29,1

to 1 E,2 6,9 11 1 15,2 15,6 U 1 6,4 6,1 U 1 6.! 6,1 U 1 11,l 11,1 15 1 11., 20,1 u 1 6,a 1,0

1 2 •1.9 •1,9 2 2 z••' n,a l 2 11,5 11,5 • 2 45,! •• ,5 5 ;,i 21 •• 2,.2 7 2 1l,6 12,9 I Z 12,8 12,1 9 2 18,1 11,l

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1t 6,1 6.9 U 5,4 5.1

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9 6 11,1 111,1

g ! ti 'ti ·11 im i!~l : 1 ~::~ 2,:,:_',• 9 1 U,l

n 1 11,6 1!:;

;! i li~i H:! : : 1!:~ 1::: ! • 5,l •• , 6 I 1.0 1,1

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: ;: '::i .:::;·:=•=·:·:·

; ,,!:.~ :i~i : ,a,a

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10 2 26,2 25,1 11 2 ••• 5.6 12 2 11,5 11,1 u 2 n,1 11.1 1• 2 10,1 11,1 1! 2 4,3 1,1

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10 • 11,, u.o 11 11 1,1 7,5 12 • U,1 21,11 12 I 21,G 21,11 111 • 19,2 19,G 15 4 •• , S.1 0 5 21,2 JC,& 1 5 12,3 12,1 2 5 31.2 37,9 l 5 1,1 1,1 II 5 31,5 31,1 ~ 5 11,1 11,5 6 5 1'.! 16,2 a 5 n,1 11.1 9 5 1,5 1,1

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I 21,l 21,1 : ;::: :::: ~= i!~i ii:! 1: 2-.0 ,,,:_:•,,

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2 20.1 19,9

: 2i:i 2;:; i !l~i 1i~!

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11 e JI,& Jl,1 12 0 , •• 6,11 12 ' 6,4 , •• 13 O 11,5 19,2 15 0 ,.o 9,5

1 I 31,5 H,2 2 I 20.6 ,,,. 3 1 39,0 Jt,2 I 1 , •• ,,5 5 1 13,1 15,1 6 110,310.5 1 1 111,1 15,1 1 1 u,1 1,.2 9 1 n.a 111.1

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1 2 59,2 6G,5 :. 2 z,., 29,4 3 2 ., ••• ,.1 II 2 10,5 10,4 !I 2 JI •• 31,0 6 2 211,1 23,5 1 2 21,!I 26,9 a 2 e.s 9,l 9 2 211,11 23,5

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11 11 13,1 u.,

;: : ,t;; 1::: 111 II 5.3 5.J

1 5 21,1 31,i .a 5 5,0 5,2 J 5 19,1 ,.,, • 5 ,., •• , S 5 U,3 U,I 1 5 11,5 11,2 I 5 11,1 1Zo5 9 5 JZ,2 31,6

to 5 5.1 6,G 11 5 23,C 22,0 12 5 1,7 1,1 U 5 10.1 11,t 11 5 5,2 5,1

1 1 n,9 n,f 2 I 1,0 ,., J 6 31,1 31,t • ' 1,2 1,9 ! 6 23,2 22,f 6 6 6,1 1,4 1 6 .... 15,0 I 6 8.11 1,3 9 6 11,2 10,f

11 6 10,1 ,, •• 12 6 J,I J.t

U 6 12,3 12,0 1 l 21,5 29,J 2 1 1,9 l,J J 1 20,1 21,1 4 1 11,1 u.a

1 U,8 1',1 1 15,0 15,4 1 11,, 11.2 l 16,• U,J 1 ,., 5,11 1 ,.1 9,7 1 1.2 1,6 I 16,I 11,J 1 n.11 n,J : 1::: 1;::

! :ti :l:!

I ii :,i:: .. :l~_.,1,; 1: 2:::

~ :: 1::~ 12.•

: ;: 1::1 't: ~ ~ u:: ~t: J 11 ,.2 10,1 • 11 1,1 2,5"' 5 11 11,. U,I ••••"R•ill••••••• O O Jl,9 .,,6 I O , •• 9 16,1) 2 o 21.0 21.1 J O 111,9 ,.,, II O IID,J 41,6 5 D 11,11 1.:1,2 6 0 u.s 22,1 1 o n,J n., I O 6,0 5,2

10 O 11.1 11,1 U D 3,9 3,11 13 0 !1,0 5,7 15 0 Z,1 2,2 0 1 111,9 11,1 :I: 1 21.11 JC.6 1 1 11,9 16,9 II 1 ZG,l 22,0 s , n., 11.1 I I 29,9 21,2 1 1 16,3 16,5 I 1 22,6 21,1 9 1 J,5 l,7

10 I 29.0 2',4 11 I t,1 6,5 12 I U,1 1',t 12 1 11,6 19,6 U 1 5,6 5.8 111 1 12.a 11,1 I! 1 3,9 J,1 D 2 26,1 26,ll 1 2 1,2 1,,1 2 2 11,J U,D l 2 111,5 U,I 11 2 29 •• JD.6 5 2 11,S 19,4 t 2 11.0 11,5 9 .a 1.11 6.4

10 2 ll,2 H,O 12 2 n,1 1!1,9 12 2 U,9 15,9 11 2 1,5 1.1 0 J .... 11,5 1 1 15,1 16,6 2 l 40,5 112,1 3 l 1.1 1,2 II l 21,9 21,1 5 3 i4,1 23,11 6 l 21,l 26,5 1 J ,.o ,.o I J ll,8 311,l

' J "·' 16,9 111 3 21,9 22,0 12 l 6,1 1,9 U J 1G,6 11,l 11 J U,2 111,1 0 11 J0,1 Jl,2 2 • 2l,I U,1 J I 9,1 9.8 II II lJ,1 32,a 6 II 26,6 25,!I 1 • 2.1 1,1 I II H,1 H,1 9 • !I.I 1,6

10 11 20.2 20.• n • s.• 1,9 12 • ,.1 6,5 ,. ••• , •• 1

0 5 21.6 20,9 1 5 1,1 9.9 2 5 u.1 211,1 J 5 u., 12,6 11 5 11,2 11,1 6 5 32,1 32,2 I 5 21,l 21,8 9 5 J,5 3,9

10 5 11.• 11,1 u s n.s n.o U 5 11,1 11,1 0 6 U,1 U,4 I 6 1,J 5,1 2 6 11,1 19,5 J ' •• 2 4,1 II 6 18,1 11,1 9 6 1,6 1,1 6 6 11.1 11,7 1 6 1,2 1,3 I I 11,6 n,9 • ' 8,1 9,5

10 6 19,9 16,0 11 6 ,., 5,5 U 6 ,.1 ,., o ., u.a 24,9 1 1 111,2 15,0 a 1 21,1 aa., 3 1 5,1 1,7 II 7 21,5 21,5 5 1 10.1 10,9 6 1 ,,,., 19,2 f 1 5,0 1,5 I 1 11,1 11,J

10 1 11,a u.o 11 1 J,6 3,1 U 1 1!1,5 15,1 o a za,1 zz.5 2 a n., 11,1

J I 12,2 U,2 II I 12.1 12,6 5 I 5.5 , ••

: : t; i:i '! ! :!~i :!] 1 i ti tl : 11.m ir 2 11 8,0 1,9 J 11 2,1 2.1

: .. !! •• ~1;:,.!!:! 1 0 60,6 62,1 J O 211,1 25,1 • O 16,2 11,0 5 0 111.6 ••• 9 6 0 7,J 1,1 1 0 28,1 21.1 9 0 16,l 15,6

10 O 5,6 5,1 11 0 22.• 21,1 12 0 !I,! 6,J U D 16,3 16,0 1 , n.o n.• 2 1 605 J,4 3 1 12,1 12,1 11 1 U,l 12,1

5 1 "·' 11,9 6 1 5,5 9,4 1 1 6,1 5,5 I 1 10.J 10.1 9 1 19,J H,5

10 1 6,1 6,J 11 I 11,S 16,8 u 1 z.• 2,1 Ill 1 1,0 ,.1 1 2 52,0 SJ,11 li Z 5,6 s.s J 2 13,1 111,1 4 2 H,S 1C,. 5 2 2!.2 26,2 6 2 11,1 5,S 1 2 31,3 Jl,4 9 2 Jl,I 31.5

10 2 10.!I 10,8 11 2 21,C li1,6 12 2 1,1 1,6 n 2 1&.1 11.s 111 2 J.5 1.,

I l 11,1 U,l 2 J 11.2 .... J 1 6,5 5,11 11 l 25,1 21,5 5 J 11,1 .... 6 J 5,6 s.s 1 J u.o n,2 I J 1,J 1,1 • J 1•.1 U,9

10 J 5,2 11,9 11 J 10,l 10,1

1 4 u.1 n,6 2 1 n,2 n,s J II Jl,2 3~.1 • • ,., •• J !I • Jl,2 33,0 • I 2.2 2.1• 1 4 32,1 n.1 • II 1,2 1,9 t • U,6 21,1

11 I , .• 1 10.1 12 • •• , 1.0 U 11 111,C U,9

1 511,118.0 2 5 6,2 1,1 ! 5 11,1 10,8 6 5 12,1 12,5 9 5 1,S 6,1

10 5 5,9 5,11 11 5 11,G 11,4 12 s 2.1 2,11 , 6 n,s n,s 2 I 10,5 12,2 J 6 36,D 35,l II 6 2,9 11,l 5 6 zs., 29,J 6 6 6.l 5,9 1 6 11., 11.11 • 6 •• , •• , 9 6 16,5 H,!I

11 6 H,7 H,9 1 1 J,t 5,6 J 1 u.2 u,1 4 1 a,1 1,1 5 115,115.9 6 1 ,.1 , •• 1 110,610.11 I 1 3,6 Z,9 9 1 6,2 1,0

10 1 2,8 i,7 II 1 5,4 5,0 1 a 2•.t 21.• 2 I U,O 13,1 J I 11,2 11,J •• ,.o 1., s I n.5 u.o 6 I 1,1 9,11 1 I H,1 1f,2 I I ••2 J,I 9 I 13,11 U,J 1 9 9,1 1,5 2 9 1,1 e • .a J 9 1,8 1,1 5 9 !1,1 5,t t 9 11,2 •• 1 1 9 7,6 1.11 I 9 1,9 J,I J 10 10., 11.a •,. 1.1 a.•• !I to U,1 15,5 6 10 ••• 5,1

! •• !! ••• ,,:.J!;! 0 0 6.8 1,2 2 fl 1,1 1,1 l I J,.1 0.9 • D 5,8 11,2 •• 11,9 11,1 I O ••• 5,t

10 fl 12,6 12,2 1J • 5,1 S,1 o I so.a ,1.1 I 1 10,1 ID,11

2 1 21,2 29,l l 1 11.1 12,1 • 1 n.2 u.• 6 1 ., •• U,4

n:.1i::'!.:.1.i!:• .. 1::

i;:.;lu i ;m 11.~=_:i,: i : 1::~

2 5 1::: :ti

. .l::: ! : .. ,:.:\:i:• I! .u ;m

10 1;:i J~· 1 H:i ~,::::,·:::_·:::. ,:

::5 1!:: 1t~ 1::~ 11,1 1i,:_l,

;;l il:l :iJ C

1~:i tL ! .. l~.,-21: ... !;! 1 O ll,J 12,1 J O 2!,:;; 21., • C 6,2 s,, 5 C U,4 IIE,J 1 D 23.~ 21,Z 9 0 9,6 9,D

11 '16,2 16,1 1li O s. 1 !,2

1 1 5,5 5,2 J 1 10,C 9,l • 1 1,1 10,1 5 1 5,8 4,1 6 1 1[,6 10., 1 1 s.2 4,Z

12 1 2,f ,.,. 1 2 32,• ll,I 2 ii 11,C 11,6 l 2 u.• 2,,!1 11 2 10., 11,) 5 2 21,6 29,6 6 Z 8,11 l,J l Z 21,l U,7 a 2 a,2 a.z I 2 16,1 16,2

10 2 l,1 1,1 ,. 2 11,!: 11,6

1 J 1., 1,6 Z l 1G.~ U,8 ] J 15.6 16,J 6 l 10,4 10,6 1 J 5,6 4,8 I l 1,3 9,0

11 ) 5,6 5,9 1:i l l,O 3,1

1 • n.• 111,, J I 2l,3 Zl,8 11 4 l,8 ,,1 ! 4 u.2 26,7 1 • 22,5 12,6 9 • 21., 2.:.0

II 11 1',8 l'J,2 1 5 11., 11,1 l 5 11,5 11,6 II 5 , •• 5,1 5 s s.1 ,.a 9 5 •.1 5,0

10 5 1,1 4,11 1 6 u.1 21.s a 6 ,.4 s.s J 6 21., 26,4 • 6 s., •.• 5 6 20,1 "·' 1 6 11,2 11.1 9 6 19.6 n.1 2 1 t,] 6,6 II 1 J,9 1,1 • 1 5.2 •• 6 7 1 i,1 1,l 1 1 20.s ao.o a 1 ,,a 1,1 J I 12,9 U,1 I I 1,1 l,J 9 I 12,G U,J , • 2,0 a,6• 1 I 15.J 15,11 1 9 ,.o 6,0 2 9 •• J 5,1 • 9 2.1 2.1•

51

........ , ...... . C fl 16.1 16,2 z C 11,6 U,1 I ti 11,1 10,9

1C O J,8 l,1 o 1 a., 2~.1 1 1 l,C 2,5 2 1 n., 21., J 1 5,1 •• , • 1 H,l H,6 5 1 ,., 6,5 & 1 ZJ,l 22,~ l 1 B,2 l,~ 1 1 1c.a 11,1 , 1 ,.a 1.e

1fl 1 18,6 11,5 11 1 1,6 0,6•

1 2 u., 12,8 2 2 12,& U,l 3 2 l,,J 6,2 4 2 J,J 8,J 5 210,710.2 J 2 5,1 5,1 I 2 l,Z 1,{I

10 2 8,ij @,ij 0 J 21., 20,J 1 J ...... , J l ,-,, 9,5 • 3 25,C 2,.1 5 J 1,2 '·" t l i1,9 2~,2 I l 11,0 16,J t ' ,., 6.~ 1 • 7,5 J.~ 2 II 1],2 1J,) • • U,1 U,l 5 • 5,9 5,11 I • 10,1 9,9 9 • •,J •• 5

10 4 6,2 ,., 0 5 11,J 11,5 1 5 5,5 6,0 .; s u.1 15,11 l 5 J,1 ••• 11 5 15,2 ... , 6 5 12,9 12,1 I 5 17,1 16.t 9 5 9,] 5,J 0 6 ,., 5,11 1 6 4,1 1.1 2 6 1C,2 10,2 • 6 J,5 7,6 ! 6 5,5 5,2 6 6 7,2 .1.11 8 6 10,,'il 11,1 0 7 1•;2 18,J 2 l 16,5 16,6 11 1 u., u.o t 7 11,2 U,1 o a 11.1 s.1 1 8 2,5 3,5 ~ 2 I ••• J,9 -. .. ' •• ';0 .. ,.5.6 1 ~ 14, 1 1], l ~ o u.t n., 5 0 1!:,! 15,l 1 0 10,5 10.• 8 G 2,1 2,• 9 0 19,l H,l 1 1 .lJ,9 21,0 2 1 u.a o.5 l 1 11,3 11,1 5 1 ,.s 5,,) 7 1 12,.i 12,7 I 1 U,8 11,U 1 2 ZC,5 20,6 Z 2 5,8 5,9 l 2 2C,1 19,9 5 2 15,t 15,5 1 Z ••• 11,1 9 2 h,8 1,,2 1 J 9,6 e.2

5,0 5,l 11,t 11,1

9. 1 ~- 5

:i:: :~:i 1::: 1t~ 1:;: 1;:i 11,t 12,) 2,J 2,J

'·" 1f,5 J,6 l,7

,~:! 1~:! 12., 12., 2., 2,9

1::! 1i:: n.1 ,,,s 6,J 1,1

l n• 1•,-~;f ... 5,S O o 1t.8 11,Z 2 0 ,,1 5,8 3 o 2, 1 ~. J• • o s,r •.1 5 Q .,1 l,'i & C 16,6 1,;,e 7 0 s.z i.1 C 1 1'.l 15,5 2 1 u.c 12,1 I 1 10, 1 •.J 5 1 5,1 !,2 6 1 5,6 5,l l 1 5,5 ••& f' 2 U,ij 1',9 1 2 11, ~ J, l 4 :.I 15,J 15,l 3 2 3., 2,1 4 2 12,2 12,2 6 2 tG,6 10,6

~ ~ 1::: 1::i 2 3 10,9 11,2 3 l l,2 1,1 • l 12,l 12,9 • J •• , 9,J 0 • 'I,] ,.1 Z I 15,0 15,6 3 • !,1 ,.1 I 4 11,11 U,2 0 5 12,l 11,5 2 5 1C,6 11,4

: ••• ;•R•:;! ... !:! 1 O 1t,O 16,l J O ,.1 •• , 1 1 u,s u.a

1 2,6 1,6 1 u.z 11., 2 !,1 5,0

52

Fig. 3.--Structure and unit cell packing of tricyclopentadienylscandium. The atoms are displayed as the 50% probability ellipsoids for thermal motion.

53

cc

(D ----------------

54 ·

only one carbon atom. The result is a polymeric arrangement

of two symmetry related chains of Sc(c5H5 ) 3 units.

The average scandium-carbon bond length of the

. 0

penta-hapto-cyclopentadienyl rings is 2.49 A (Table 12),

and the average distance of the scandium atom from the

0

planes of the two cyclopentadienyl groups is 2.19 A. Both

of these values compare favorably with the standards reported

0

for [(C5H5) 2sccl] 2 : (4) 2.48 and 2.17 A, respectively. The

data in Table 13 indicate that the scandium-carbon distance

fits in well with the general trend found among first-row

transition metal ~-cyclopentadienyl complexes. As Stucky

has pointed out (49), the only metal-carbon bond lengths

which are significantly shorter than one would predict on

the basis of_metallic radii are those found with iron and

cobalt.

For each ring the results of least-squares best-plane

calculations are shown in Table 14. The fact that ring C

is in an environment quite different from that of rings A

and B does not affect the planarity of the group; the maximum

0

deviation in any case of 0.01 A from the plane.

55

TABLE 12

0

INTERATOMIC DISTANCES (A) AND ANGLES (DEG) FOR TRICYCLOPENTADIENYLSCANDIUM

Sc-Cl Sc-C2 Sc-C3 Sc-C4 Sc-CS

Ring A

2.525(4) 2.495(5) 2.471(6) 2.461(5) 2.500 (5)'

Ring .. C

Sc-Cll 3.847{4) Sc-Ci2 3.020(5) Sc-Cl3 2.629{4) Sc-Cl4 3.341(5) Sc-Cl5 3.961(4) Cl-C2 1.372(9) C2-C3 1.371(9) C3-C4 1.416(9) C4-C5 1.391(7) CS-Cl 1.381(7) Cll-Cl2 1.425(6) Cl2-Cl3 1.383(6) Cl3-Cl4 1.430(7) Cl4-Cl5 1.363(6) Cl5-Cll 1.423(6)

C8-Cll C4-Cl0 C2-Cl3 Cl-Cl2' C5-Cll' C5-Cl2' C5-Cl5' C5-Cl4

3.10(1) 3.16(1) 3.23(1) 3.29 (1) 3.35(1) 3.39(1) 3.40(1) 3.42(1)

Bonded

0

Nonbonded Distances (A)

Sc-C6 Sc-C7 Sc-CS Sc-C9 sc-Cl0

Ring B

2.473(6) 2.474(4) 2.521(4) 2.511(5) 2.505(5)

Ring C'

Sc-Cll' Sc-Cl2' Sc-Cl3' Sc-Cl4' Sc-Cl5' C6-C7 C7-C8 C8-C9 C9-Cl0 Cl0-C6

2.519(4) 3.329 (5) 4.144(5) 4.032(5) 3.i51(4) 1.402(7) 1.475(7) 1.408(6) 1.419 (8) 1.382(8)

C3-Cl0 3.13(1) C7-Cll 3.21(1) C6-Cl2 3.24(1) C4-C9 3.30(1) C7-Cl2 3.35(1) Cl4-Cll' 3.39(1) Cl-Cl3 3.41(1) C6-Cll 3.43(1)

TABLE 12.:.-continued

Bond Angles

-· C4-Cl-C5 107.1(5) Cl-C2-C3 C2-C-3-C4 106.3(5) C3-C4-C5 Cl-C5-C4 108.6(5) C7-C6-Cl0 C6-C7-C8 109.0(4) C7-C8-C9_ C8-C9-Cl0 109. 9 (5) C6-C10-C9 Cl2-Cll-Cl4 106.3(4) Cll-C12-Cl3 Cl2-C13-Cl4 107.4(4) C13-C14-C15 Cll-C15-Cl4 108.9(4)

~ C' is related to C by the symmetry operations (x, 1/2 - y, 1/2 + z), followed by a unit cell translation in z.

56

110.6(6) 107.4(5) 107.9(5) 105.2(5) 109.0(5) 108.7(4) 108.6(4)

57

TABLE 13.

COMPARISON OF :METAL-CYCLOPENTADIENYL CARBON BOND DISTANCES

Compound a

M-ir-C (Sc-C)- r(Sc)-

Ref. (M-C) r(m)b

Sc(C5H5 ) 3 2.49 (5)

( (C5H5 ) 2sccl] 2 2.48 (4)

c5H5TiCl(ONC9H6 ) 2 2.41 o.oa 0.15 {52)

{C5H5)2Ti(C6H5)2 2.31 0.18 0 .15 {53)

c5 H5V{CO) 4 2.28 0.20 0.28 (54)

C5H5Cr {NO). 2NCO 2.20 0.28 0.34 {55)

c5H5Mn(CO) 3 2.17 0.31 0. 35 {56)

. Fe (C5H5 ) 2 2.04 0.44 0.36 (57)

c5H5Co(CH3c2cH3 ) 2co 2.07 0.41 0.37 (58)

Ni(C5H5 ) 2 2.20 0.28 0. 38 (59)

~ Representative compounds have been chosen.

b Metallic radii as given in L. Pauling, "The Nature of the Chemical Bond," Cornell University Press, Ithaca, N. Y., 1960, p. 403.

58

Plane

A

B

C

Atom

TABLE" 14

BEST WEIGHTED LEAST-SQUARES PLANES FOR TRICYCLOPENTADIENYLSCANDIUM

0.8482x + 0.4935y - 0.1927z - 6.5220

0.869lx - 0.3680y - 0.3307z + 1.6838

-0.58llx + 0.7008y - 0.4137z + 2.4670

Deviation of atoms from planes (A)

Plane A Atom Plane B Atom Plane

= =

=

C

Cl -o.ooa C6 0.01 Cll -o. 01 ·

C2 o.oo C7 -0.00 Cl.2 o.oo

C3 0.00 ca -0.00 Cl3 0.00

C4 -0.00 C9 0.01 Cl4 -0.01

cs o.oo Cl0 -0.01 ClS 0.01

Sc -2.19 Sc 2.19 Sc 2.sob

a The standard deviation for the distance of each carbon 0

atom from the plane is 0.01 A and for the scandium atom, 0

0.04 A.

b The distance of the scandium atom from the plane of C 0

is -2.21 A.

0

0

0

59

Figure 4 shows the bond lengths and angles in the

three cyclopentadienyl moeities. The average carbon-carbon

0

bond distance of 1.40 A is well within the expected range

(45). It should be noted that the bridging c5H5 group does

not differ significantly from the terminal groups with

respect to either bond distances or angles and, within the

group itself, no unusual variations are found.

Table 11 shows that the scandium atom is bonded

equally to all five carbon atoms of ring A and of ring B.

On the other hand, the association with rings C and C'

appears to be of a fundamentally different nature. The

0

Sc-Cl3 bond is 0.15 A·longer than the average found in A

. and B, and the bond makes an angle of 73° with the plane of

ring C. The Sc-Cll' bond distance is within the range of

those noted for A and B, and the bond makes an angle of 61°

with the plane of ring C'. A further survey of Table 11 and

~igure 3 indicates that the interaction is through only one

carbon .atom. This is especially evident for Cll', where the

next closest approaches to the scandium atom (C12', ClS')

0

differ by only 0.18 A.

One would expect the scandium-carbon bond to make an

angle of 55° with the plane of the ring if the carbon atom

60

Fig. 4.--Bond distances and angles within the cyclopentadienyl groups for Sc (C5H5) 3. ·

61

(A)

1.42

( B)

1.41

. (C)

1.43

62

· were sp 3 hybridized (50, 51) • Unfortunately, the meaning of·

the observed angles (61, 73°) _is probably obscured by the

rather strict steric requirements obtained by placing four

cyclopentadienyl groups about the scandium atom. It is

possible that the geometry of the bridging c5a5ion is simply

the result of the minimization of the potential energy of

the crystal. However, the structural parameters may perhaps

be more reasonably interpreted in terms of a preferential

interaction between one carbon atom and the scandium atom.

To the extent one wishes to view a preferred orientation as

an implication of covalent bond character, this represents

the first experimental evidence for an appreciable amount of

covalency in an organoscandium compound.

The crystal structure of tricyclopentadienylscandium

also has a direct relation to the inaccurately determined

·structure of tricyclopentadienylsamarium (43) (Table 15).

The only real difference in the lattice parameters is that

b for the samarium compound is almost twice the value for

the scandium analog. Wong, Lee, and Lee (43) state that

only a few very weak reflections were found for kf2n. A

careful search between layers ink for Sc(c5H5) 3 showed no

such intensities. Further studies of Sm(c5H5) 3 and related

compounds _may reveal even closer similarities between the

two substances.

... TABLE 15

COMPARISON OF CRYSTAL DATA FOR Sc(C5H5) 3 AND Sm(C5H5 ) 3

63

Sc (C5H5.) 3 · Sm(C5H5 ) 3

Crystal system Orthorbhombic Orthorhombic

Space group Pbcm or Pbc2 1 Pbcm or Pbc21 0

a, A 12. 881(5) 14.23(2)

0

b, A 8.954(4) 17.40(1)

0

c, A 9.925(4) 9.73(2)

v, 03 A 1145 2295

z 4 8

Space group Pbc2 1 Pbcm

Selected

Trichlorotris(tetrahydrofuran)scandium

Herzob, et al. (60) have shown that anhydrous heavy

metal halides form complexes with tetrahydrofuran under

anaerobic conditions. All lose tetrahydrofuran quantita­

tively in air and react with water. More recently, Finke

and Kirmse (61), have made solubility studies of Sccl3 in

64

various solvents. They also deal with the formation of

addition products of Scc13 and discuss the infrared spectra

of the solutions and the dry addition products. They

indicate the formation of coordinate bonds of Scc13 with the

oxygen~containing solvents.

Trichlorotris(tetrahydrofuran)scandium was prepared

by reaction of anhydrous scandium chloride with THF under

anaerobic conditions (6). Single crystals of Sccl3 (c4H8o) 3

were grown by slow evaporation of solvent and sealed in

thin-walled glass capillaries. Preliminary unit cell

parameters were determined by precession (Cu Ka) photographs.

The crystal system is monoclinic. Systematic absences allow

the space group to be P21/c. The lattice parameters as

determined from a least-squares refinement of (sin0/A) 2

values for 12 reflections are 0

a= 8.890(4) A

0

b = 12.842(6) A

0

C = 15.485(6) A

V = 1767 ~3

e = 92.243(5) 0

-3 The calculated density is .l.38 g cm for Z = 4. Complete

three-dimensional single-crystal X-ray diffraction data

65

were obtained on an Enraf-Nonius CAD-4 diffractometer

controlled by a PDP8/E computer. A graphite monochromator,

with-the (002) plane in diffracting position was used to

obtain monochromatic Cu Ka radiation. The radiation was

detected using a scintillation counter with pulse height

discrimination. The crystal, a plate of dimensions 0.10 x

0.30 x 0.30 mm, was aligned on the diffractometer1 such that

one.long axis was coincident with the~ axis of ·the diffrac-

tometer.

The diffracted intensities were collected by the

scan technique with a take-off angle of 3.5°. The scan rate

-1 was variable and was determined by a fast 20°(min } prescan.

Calculated speeds based on the net intensity gathered in the

-1 prescan ranged from 7 to 1 min .• Background counts were

collected for 25% of the total scan time at each end of the

scan range. For each intensity the scan width was determined

by the equation

scan range= A+ B tane

where A= 1.0° and B = 0.46°. Aperture settings were deter-

mined in a like manner with A= 4 mm and B = 4 mm. The

crystal-to-source and crystal-to-detector distances were 21.6

and 20.8 cm, respectively. The lower level and upper level

discriminators of the pulse height analyzer were set to

obtain a 95% window centered on- the Cu Ka peak. As a check

on the stability of the diffractometer and the crystal, one

reflection, the (211}, was measured at 30-min intervals

during data collection. No significant variation in the

reference intensity was noticed.

The standard deviations of the intensities, oI, were

estimated from the formula

where CN is the counts collected during scan time Tc amd B1

and B2 are background intensities, each collected during

the background time TB. One independent quadrant of data

was measured out to 20 = 114°. A total of 1227 unique

reflections were collected which had intensities greater

than background.

The intensities were then corrected for Lorentz,

-1 polarization, and absorption (32) effects (µ· = 56.6 cm ) •

· Fourier calculations were made with the ALFF programs (36).

The full-matrix, least-squares refinement was carried out

using the Busing and Levy program ORFLS (35). The function

w ( IF 1-1 F I ). 2 was minimized. No corrections were made for 0 C

67

extinction or anomalous dispersion. ~eutral atom scattering

factors were taken from the compilations of Cromer and Waber

(63) for Sc, Cl, o, C, and H. Final bond distances, angles,

and errors were computed with the aid of the Busing, Martin,

and Levy ORFFE program (37). Crystal structure illustrations

were obtained with the program ORTEP (41).

Preliminary density calculations indicated the pres-

ence of four molecules of sccl3 (c 4a8o~ in the unit cell.

The structure solution was first sought using heavy atom

methods. The interpretation of the Patterson map was

ambiguous; no peaks verified with any certainty. The

electron density map was complex and many attempts at

positioning the nonhydrogen atoms yielded an R factor of no

lower than 40%. At this point the structure solution was

sought by direct methods using the program MULTAN (33) with

three starting phases and an absolute figure of merit of

1.4271. An electron density map phased on the scandium,

chlorine, and oxygen atoms yielded the positions of the

remaining nonhydrogen atoms. Several cycles of least-

squares refinement with isotropic thermal parameters for

all atoms produced a reliability index of

R = E(IF I-IF l>/CEIF I>= 0.14 0 C 0

68

Conversion to anisotropip temperature factors and additional

cycles of refinement of all nonhydrogen atoms led to a

final R· = 0.077 and 1

R2 = (rw(IF0 1-IF0 1> 2/E(wF0 ) 2]½ = 0.077

2 where w = 1/cr • Unobserved reflections were not included.

No attempt was made to locate the hydrogen atoms.

The atomic positions and anisotropic thermal para­

meters of the nonhydrogen atoms as obtained from the final

least-squares cycle are given in Tables 16 and 17, respec­

tively. In the final cycle, no parameter shift was greater

than 0.02 of the estimated standard deviation. No systematic

variation of w(IF I-IF 1> 2 vs. IF I or (sin8/J) was observed. 0 C 0

Observed and calculated structure factor amplitudes are

given in Table 18.

The structure consists of four discrete Scc13 (c4a8o) 3

molecules within the unit cell. Figure 5 shows the coordina­

tion sphere of the scandium ion with the 40% probability

envelopes of the anisotropic thermal ellipsoids. Figure 6

shows a similar view of the entire molecule. The unit cell

packing is shown in Figure 7. Intramolecular distances and

angles together with their estimated standard deviations are

listed in Table 19.

69

TABLE 16

FINAL ATOMIC POSITIONAL PARAMETERS a

FOR ScC1 3 (c4a8o~

Atom x/a y/b z/c

Sc 0. 7618 (2) 0.2436{2) 0.2431(1)

Cl (1) 0.7680{4) 0.4028(3) 0.3252(2)

Cl (2) . 0.9451(3) 0.1608(3) 0.3402(2)

Cl (3) 0.5756{3) 0.3100(3) 0.1396{2)

0(1) 0.7562(9) 0.0966(6) 0.1657(5)

0(2) 0.5862(8) 0.1709(6) 0.3129(5)

0 (3) 0 .9390 (8) 0.2844(5) 0.1574(5)

C (1) 0.7266(23) 0.0918(11) 0.0725(8)

C (2) 0. 7572 ( 34) -0.0211(13) 0.0486(12)

C (3) 0.7483(26) -0.0795(12) 0.1283(12)

C (4) 0.7846(20) -0.0080(9) 0.2020(9)

C(5) 0.5872(15) 0.1644(12) 0.4083(8)

C(6) 0.4403(18) 0 .1193 (16) 0.4264(9)

C (7) 0.3542(14) 0.1014(12) 0.3478(10)

C (8) 0.4497(15) 0.1255(14) 0.2754(9)

C (9) 1.0778(14) 0. 2235 (11) 0.1472(10)

C (10) 1.1455(15) 0.2683(11) 0.0696(10)

C (11) 1.1007(13) 0.3817(10) 0.0685(9)

C (12) 0.9441(13) 0.3799(9) 0.1023(8)

a Standard deviations in parentheses refer to last digit -quoted.

Atom

Sc

Cl (1}

Cl (2}

Cl (3}

0(1}

0(2}

O (.3)

C (1}

C (2}

C (3}

C (4).

C(5}

TABLE 17-

ANISOTROPIC TEMPERATURE FACTORS a,b (x 10 4} FOR ScC1 3 (c4H8o} 3

102 (3) 67 (2)

240(6) 80(3)

134(4) 104(3)

160(5) 95{3)

236(16) 63(6)

126 (11) 115 (8)

150(2) 72(6)

645(56) 80(12)

1083(106) 89(15)

673(68) · 79(13)

465 {42) 45 (9)

221 {25) 177 (17)

42(1)

64 (~)

6 3 {2)

60{2)

44 (5)

50{4)

61 {5)

31(8)

71(12)

95 {13)

6 7 {9)

36 {7)

1(2)

5 ( 3)

9 {3)

11 {3)

6 { 8)

-33(8)

7 (7)

1 (21)

87(32)

13(24)

12(16)

-49(18)

8(1)

13 {3).

-9 (2)

-15(2)

3(7}

-5(6)

37(6)

-6(16)

5 (28)

-36(24)

4(15)

23 (10)

70

5 (1)

-16(2)

19(2)

15(2)

3(4)

11(5)

10 (4)

-16(7)

-7 (11)

-20(11)

6 (7)

12(9}

C{6) 251(31) 264(26) 54(10) -95(25) 38(14) -4(13)

C(7) 148(.22) 139(15) 102(12) -30(15) 41(13) -12(11)

C(8) 166(23) 222(21) 73(10) -100(19) -21(12) 24(12)

C(9)

C(l0)

C {11)

C(12)

179 (22) 125 (14)

209 (24) 107 (13)

180 (22) 77 (10)

183 (21) ·75 (9)

116(12)

115(12)

83(9)

60 (8)

53(15)

25 (15)

2 (12)

-6(12)

97(14)

81(15)

51 (11)

21(10)

40(10)

31 (10)

0

15(7)

a Standard deviations in parentheses refer to last digit quoted.

b Anisotropic thermal parameters defined by exp

[-B11h 2 + s22k 2 + s3312 + 2B12hk + 2S13hl + 2B23kl)]

71

TABLE 18

OBSERVED AND CALCULATED STRUCTURE FACTORS FOR TRICHLOROTRIS(TETRAHYDROFURAN)SCANDIUM

0 U u •• u.o -2 1Z 11.0 u ....

-j .!!J! .:!:! -: g !t: ::::

~ ll!:llll

. _, ' -• ' ' -, ' _, ' . ' -• ' -•

-• . _, _, ' -• ' -• -• _, ' ' ' _, ' . ' ' _, ' _, ' . ' ' ' ' ' -• ' _,

-• ' -• ' _, ' . _,

-•

~11 !!l! '!1ll -i i Ii I! =~ ~ ~::! t~:!

l U.• 1••" •) l Ul.J lllloJ

.: ~ ii~i '!m

.: : ft:~ it: :! l 11.5 111.l

' ' _, ' -• '

-• . . . _, ' ' _, ,

-• . . ' _, ' _,

' _, ' _, ' -•

' _, ' ' _, ' ' ' ' ' -• ' ' ' ' . _, ' . -• . -• . ' ' -• . . '" •I 10 _,"

" _, 11

-z 11

'" ·l U •• II u

'" -2 U

'" "

:! : n~ mi -: ~i:! :::i

o , o • ., ,o,t •I ' hot .ol,,J

l • Uol til.11 •2 t ,,., 11,J

' i !;~i !E; .: : m~ HI!

: i 11~1 l!~l 0 1 , ••• , •••

•I I J1,'J Jl,J I I u., ,o.,

•l 1 11,0 U,l J J lll,11 U,,1

1 u •• u., ' ... , ... -~ r u,. 21.,

, I I'll.I U.~ 1 B,O 9,0 J 10,Z 10,2 -i 1 IU,~ 11,i,

. -• -, '

-• -•

' -•

-• . '

'

_, _,

' . _, ' _, _,

-•

_, _, ' _, '

-• ' _, '

_,

_, -• ' . ' -• ' _,

_, -•

}t.~ ~·-, 11,1 1.,,, 10,i, J4,l

1 H,11 J'>,I •l •'-• u,,

U,H •9,1 u .• 1, .• , ~J,l ""•"' 1os., n,J ,,., n.1

t l0,1 z,._,;i 11,11 14,I

U,l l~,1 »,I JJ.2 ,,,. 11,1 ,~., 10,1

0 , ... , , •• o •I lZ,1> U,'i •l 2 1,,1 '"••

' _,

. -•

-

--

---.

--

.. ' .. •l 10

" . " .. .. .. 'u

•I II 'u

_,

' -,

' ., _, ' '

. _, ' ,

-• ' '

-, -• . ,

u u u

:: i mi mi

.,

'" '"

_, -• ' _, ' '

-• , . _,

_, -• ' -, . -• _, ' ' -• ' ' _,

-• _,

' ' -•

' _,

' _, . ' ::

_, ' ,

-• ' _, _,

' . ;1 I fll! ;Ill :1 i im rm

1i 1n,e 11.0 I 10 'ioJ 10,1

·) :~ '!:! 't~ ; .. !;-,;:~:••::~

-I O •0.1 "•l

72

I O 1.,,.1 11,'t

-: : it: u:: _: i im im -; i g~1 mi

1 u.1 n., -t I 11>,1 U.l

S l 11,1 •••• I U,l U,l

0 l U,J <U,J -• z u.a H,s -z l 10,t 10,I

l U,l U,. 2 ll,1 14,I l 24,1 2',I l 20,• lt,I

-, z n.• u.a l 11,2 11,J

•I J •1,1 ll,I

1: '::; ';:: -~ , u.e 20,• ~ J 11.1 11 ••

-~ i ii~i m! :i i 1m mi -l : !t~ H::

: :t: :::: _, : ,!:! .::~ _, :::~ !t:

l U,t n.• JO,. ll,I 12,l U,I

-: , i~~i m~ : :!:: !:::

~ 1 i!j! i!j! I 9 11,, 1$,I

) : '!:! !~:! • tot •• J !):~:!!:.):::

;J l l~l li!i -: ~ :!:t :t:

_, ' _,

' '

-• _,

0

' ' . ,

. _, ' _,

-• ' _, '

' _, I 'f t,C IC,l .. n••~•IJ••u••• l I U,J l•hl

! ! :::: i::: J l P,l· 11,0

:t ~ :::: :::: l J .U,O l••~

-J J u., IS,!> ~ J ll•• 10,2 0 • , ••• u.s

•I • U,9 U,1 -• .. ., .. ··" • • 1,0 , •• -1 ' ... , ....

,J • 9,J 11,1 •I • U,J 111,J •J • 111,T ll,l>

I ~ 7,5 'il,l u•••~•l4•uu•• l ~ U,. l~,.,

•J o U,1 u., J V 10,I ,,~ -• " .,_, ... ,

•S II H,I ll••

73

Fig. 5.--The coordination sphere of the scandium ion­with the 50% probability envelopes of the anisotropic thermal ellipsoids.

·74

75

Fig. 6.--Molecular view of trichlorotris­(tetrahydrofuran)scandium with the 40% probability envelopes of the anisotropic thermal ellipsoids.

76

77

Fig. ?.--Structure and unit cell packing of trichlorotris(tetrahydrofuran)scandium. The atoms are displayed as the 40% probability ellipsoids for thermal motion.

78

TABLE 19-

0

INTERATOMIC DISTANCES (A) AND ANGLES

Sc-Cl(l) Sc-C1(3) Sc-O(2) O(1)-C{l) C (2) -C ( 3) O (l) -c (4) O(2)-C(6) C ( 7) -C ( 8) O(3)-C(9) C(l0)-C(ll) C(12)-O(3)

Sc-C(5) Sc-C(9) Sc-C(l) Cl(l)-O(2) Cl(l)-Cl(2) Cl(l)-C(S) Cl.(2)-O(2) Cl(2)-O(3) Cl (2) -C ( 9) C1(3)-O(l) Cl(3)-O(3) Cl ( 3) -C ( 8) O ( 1) -0 ( 3) 0 ( 1) -c ( 8)

0 (2} -c (4) C ( 8) -C ( 4)

O(l)-Sc-C1(2) 0 ( 1) -ScO ( 3) Cl(l)-Sc-C1(2)

FOR Sccl 3 (c4H8O) 3

Bonded

2.406(4) Sc-C1(2) 2.415(4) SC-0(1) 2.147(7) Sc-O(3) 1.46(1) C (1) -c ( 2} 1.45(2) C(3)-C(4) 1.47(1) O(2)-C(S) 1.47(2) C (6) -C ( 7) 1.47(2) C(8)-O(2) 1.47(1) C(9)-C(l0) 1.51(2) C(ll)-C(l2) 1.50(1)

0

Nonbonded Distances (A)

3.21(1) Sc-C ( 8)

3.24(1) Sc-C (12) 3.29(1) sc-c (4) 3.39(1) Cl(l)-O(3) 3.49(0) Cl(l)-C1(3) 3.71(1) Cl(l)-C(12) 3.20(1) C1(2)-O(l) 3.24(1) C1(2)-C(4) 3.35(1) C1(2)-C(5) 3.19(1) C1(3)-O(2) 3.25(1) C1(3)-C(l) 3.39(2) C1(3)-C(l2) 2.91(1) 0(1)-0(2) 3.29(2) O(l)-C(9) 3.40(2) O(3}-C(l) 3.66(2} C(9)-C(l)

Bond Angles

87.9(2) 82.9(3) 92.5(1)

O(l)-Sc-O(2) O(l)-Sc-C1(3) Cl (1) -Sc-Cl {3)

(DEG}

79

2.420(4) 2.236(8) 2.164(7) 1.52(2) 1.49(2) 1.48 (1) 1.43(2) 1.45(1) 1.48(2) 1.51(2)

3.22(1) 3.27(1) 3.30(1) 3.42(1) 3.50(0) 3.86(1) 3.23(1) 3.33(1) 3.39(1) 3.22(1) 3.29(1) 3.47(1) 2.94(1) 3.31(2) 3.35(2) 3.70(2)

84.3(3) 86.6(2) 93.0(1)

Cl(l)-Sc-O(2) Cl (3)-Sc-) (3) O(2)-Sc-Cl(2). O(1)-Sc-Cl(l) Cl(2)-Sc-Cl(3). C ( 2) -C ( 3) -C ( 4) C(4)-O(l)-C(l) C ( 5) -C ( 6) -C ( 7)

C(7)-C(8)-O(2) O(3)-C(9)-C(l0) C(l0)-C(ll)-C(l2) C(12)-O(c)-C(9)

TABLE 19--Continued

Bond Angles

96.1(2) 90.2(2) 88.9(2)

179.5(13) 174.4(2) 108.4(14) 111.1(9) 110.6(12) 106. 2 (11) 104.4 (11) 103.2 (10) 109.3(8)

Cl(l)-Sc-O(3) C1(3)-Sc-O(2) C1(2)-Sc-O(3) O(2)-Sc-O(3) O(l)-C(l)-C(2) C ( 1) -C ( 2) -C ( 3)

C(3)-C(4)-O(l) O ( 2 ) -c ( 5 ) -c ( 6 ) C ( 6 ) -C ( 7 ) -C ( 8 ) C(8)-O(2)-C(5) C(9)-C(10)-C(ll) C(ll)-C(12)-O(3)

0

80

96.7(2) 89.7(2) 89.9(2)

167.2(3)· 104.7(12) 105.6(14) 104.0(11) 104.1(11) 108.1(11) 110.5(9) 105.6(11) 105.1(9)

The average Sc-Cl distance of 2.413(4) A is quite

short compared to that of the bridged dicyclopentadienyl-

0

scandium dimer (2.575(6) A), but this is not unusual (47).

0

The Sc-O average distance of 2.182 A is long compared to ..

that reported by Anderson, Neuman, and Melson (6) for

0

Sc(acac) 3 (2.070 A). However, Hanson (62) reports a Sc-O

0

distance of 2.18-2.26 A for the structure of tetraaquotris-

oxalatodiscandium(III) hydrate. The average carbon-carbon

0 0

distance of 1.48 A and C-O distance of 1.47 A are reasonable

for single bonds.

The bond angles of the ligands to the scandium ion

range from 82.9° to 96.7°. It is thus clear that some dis-

tortion from a regular octahedral environment is observed

81

for the coordination of the scandium ion. The configuration

of the THF rings is shown clearly in Figure 8.

As is shown in Table 20, the scandium atom lies

0

only 0.02 and 0.03 A·out of the plane of two of the tetra~ 0

hydrofuran groups and 0.25 A out of the plane of the third

tetrahydrofuran group. The carbon and oxygen atoms deviate

considerably from the plane of the rings, since tetrahydro­

furan is not a planar molecule.

82

Fig. 8.--View looking down the Cl-Sc-0 axis displaying the configuration. of the THF rings.

83

84

.TABLE 20-

BEST WEIGHTED LEAST-SQUARES PLANES FOR . ScC1 3 (C 4H8o) 3

Plane

Sc Ring 1 0.9937x + 0.0659y - 0.0902z - 6.4331 = 0

Sc Ring 2 0. 3935x - 0.9193y - 0.012oz + 0.0675 = 0

Sc Ring 3 -0.4903x - 0.4240y - 0.7614z + 7.4665 = 0

0

Deviations of Atoms from Planes (A)

Atom Sc Ring 1 Atom Sc Ring 2 Atom Sc Ring 3

0(1) -o.oo 0(2) -0.03 0 ( 3} 0.02

C (1) -0.08 C (5) 0.01 C (9) -0.14

C(2) 0.14 C (6) 0.02 C (10) 0.21

C (3) -0.15 C(7) -0.04 C (11) -o~. 20

C(4) 0.09 C (8) 0.04 C (12) 0.11

Sc 0.02 Sc -0.25 Sc 0.02

Bis(indenyl)magnesium

The properties of bis(cyclopentadienyl)magnesium

have been the subject of a great many investigations since

its initial preparation in 1954 (54, 65). As an intermediate

in the production of other cyclopentadienyl compounds, the

substance offers certain advantages over the commonly used

85

alkali metal counterparts. Mg (C 5H5) 2 may be quite readily

prepared in quantitative yield from the high temperature

reaction of cyclopentadiene with magnesium metal {26), and

purified by sublimation. Its high solubility in hydrocarbon

solvents also affords a wider range of synthetic prospects.

The relation of Mg(C5H5 ) 2 to the bis(cyclopentadienyl)

derivatives of the transition metals has proved to be a point

of some controversy (66, 67). Although compounds of the type

M(C5H5 ) 2 , {M = Mg,V,Cr,Mn,Fe,Co,Ni), are all isostructural

(68, 69-}, early magnetic, spectral, and chemical investiga­

tions led to the conclusion that the bonding in the magnesium

and manganese compounds is essentially ionic (67, 70). Sub­

sequent studies of the vibrational spectra of bis(cyclopenta­

dienyl)magnesium indicated, however, the presence of covalent

ring-to-metal bonding which is weaker than that of ferrocene

( 6 6) •

Compared to the role of the cyclopentadienyl group

in the renaissance of organometallic chemistry, the part

played by the indenyl moiety has been small indeed. Very

few indenyl transition metal complexes have been reported

{71, ·72, 73), and bis(indenyl)magnesium has been noteworthy

in its absence. Bis(indenyl)iron exists in the solid state

86

as a sandwich compound. which exhibits the gauche configura-

tion (74):

Based on the geometrical ·analogy between Fe(C5H5) 2 , one

might expect Mg(C9H7) 2 to be similar in structure to

Fe (c9a7.> 2 • Such is not the case. We wish to report the

preparation and crystal structure of bis(indenyl)magnesium,

and to discuss the relation of the new compound to the

well-known bis(cyclopentadienyl)magnesium.

Bis(indenyl)magnesium was prepared by the thermal

decomposition (190°C) of indenylmagnesium bromide in vacuum

-4 ("'10 mm) . The white crysta·lline air-sensitive substance

was separated from an accompanying yellow oil and purified

by sublimation. The net yield of pure product was 25%.

87

Single .crystals of Mg(C 9H7 >. 2 -were also grown by sublimation

and sealed in thin-walled glass capillaried. Preliminary

unit cell parameters were determined by precission (Cu Ka)

photographs. Final lattice parameters as determined from a

·2 least-squares refinement of (sin0/A) values for 12 reflec-

. .

tions accurately centered on a diffractometer are

0

a= 21.496(4) A

0

b = 12.371(4) A

0

c = 10.390(4) A

V = 2763 i_3

Data were taken on an ENRAF-NONIUS CAD-4 diffracto-

meter with graphite crystal monochromated copper radiation.

The crystal was aligned on the diffractometer such that the

rod axis was coincident with the$ axis of the diffrac­

tometer.' The diffracted intensities were collected by the

w-20 scan technique with a take-off angle of 3.5° •. The scan

. -1 rate was variable and was determined by a fast (20°min )

prescan.. Calculated speeds based on the net intensity

d . h d f 7 0 7° . -l gathere int e prescan range rom to • min •

Background counts were collected for 25% of the total scan

time at each end of the scan range. For each intensity the

scan width was determined by the equation

88

scan range= A+ B tane

where A= 1.0° and B = 0.45°. Aperture settings were deter­

min~d in a like manner witb A= 4 mm and B = 4 mm. The

crystal-to-source and crystal-to-detector distances were

21.6 and 20.8 cm·, respectively. The lower level and upper

level discriminators of the pulse height analyzer·were set

to obtain a 95% window centered on the Cu Ka peak. As a

check on the stability of the diffractometer and the crystal,

two reflections, the (112) and (410), were measured at 30-min

intervals during data collection. No significant variation

in the reference intensities was noted.

The standard deviations of the intensities were

estimated in the fashion previously described with the value

of° the parameter p setat0.02. Two symmetry related octants

were measured out to 28 = 120°; a total of 1112 unique

observed reflections (I>3a(I))were obtained after averaging.

The intensities were corrected for Lorentz and polarization

effects (31), but not for absorption 1coefficient

-1 (µ = 9.30 cm ) •

Fourier calculations were made with the ALFF program

(35). The full-matrix, least-squares refinement was carried

out using the Busing and Levy program ORFLS (34). The

89

function w(IF l~IF 1> 2 was minimized. No corrections were 0 C

made for extinction or anomalous dispersion. Neutral atom

scattering factors were taken from the compilations of

Cromer and Waber (63) for Mg, C, and H •. Final bond distances,

angles, and errors were computed with the aid of the Busing,

Martin, and Levy ORFFE program (36). Crystal structure

illustrations were obtained with the program ORTEP (40).

Preliminary density calculations indicated the

presence of eight molecules of Mg(C9H7) 2 in the unit cell.

This was interpreted to mean that there must be· two indepen­

dent molecules in the asymmetric unit, since the space group

P21 21 21 has only four~fold general positions. The interpreta­

tiop of a sharpened Patterson map, although quiet ambiguous,

led to the correct placement of both magnesium atoms. Fourier

and difference Fourier maps phased on the two magnesium atom

positions led to a correc::t partial model, and subsequent

Fourier calculations preceded by isotropic least-squares

refinement of the magnesium and carbon atom positions, allowed

the location of all 38 nonhydrogen atoms in the asymmetric

unit. Anisotropic refinement with unit weights led to

agreement indices of

Rl = E(IF I-IF 1)/EIF I= 0.08 0 C 0

and

R2 = (Ew(IF I-IF 1> 2 /Ew(F >2]½= 0.092 0 C · · 0

Inclusion of hydrogen atom contributions at calculated

positions, and the use of a weighting scheme1 based on the

satisfaction of the criterion that ( r F 1-1 F I) 2 not vary . 0 C

with either IF I or (sin8)/A produced final values of 0

90

R1 = 0.066 and R2 = 0.069. Unobserved reflections were not

included. The largest parameter shifts in the final cycle

of refinement were less than 0.20 of their estimated standard

deviations. A final difference Fourier map showed no feature

- 03 greater ·than 0.4e /A, the standard deviation of an observa-

tion of unit weight was 1.04. The final values of the posi­

tional and thermal parameters are given in Tables 21 and 22,

respectively. Observed and calculated structure factor

amplitudes are listed in Table 23. Figures 9 and 10 show the

magnesium atoms and their associated indenyl rings ..

Bis_(indenyl)magnesium in the solid state exhibits

magnesium atoms in two different environments and indenyl

groups of a fundamentally different nature. As shown in

1 The weighting scheme is based on essentially unit

weights except for a diminished contribution from the very intense reflections.

91

TABLE 21

. FINAL ATOMIC POSITIONAL PARAMETERS a,b

FOR DIINDENYLMAGNESIUM

Atom: x/a ' y/b z/c

Mg(l) 0.4238(1) 0.8469(2) 0.5414(3) Mg(2) 0.3932(1) 0.6182(2) 0.9413(3) C (1) 0.3551(7) 0 .8116 (11) 0.3567(15) C(2) 0. 4085 (11)· 0.8671(9) 0. 3223 {13) C (3) 0.4608(8) 0.8051(11) 0.3342(13) C (4) 0.4415(6) 0.7041(10) 0. 3820 (11) C(5) 0.4745(6) 0 .6071 (13) 0.4155(15) C(6) 0.4404(11) 0.5188(11) 0.4631(19) C (7) 0.3761(12) 0.5252(14) 0.4701(18) C (8) 0.3446(6) 0.6125(13) · 0.4372(16) C(9) 0.3769(5) 0.7058(10) 0.3933(11) C (10) 0.3946(9) 0.7352(11) 0.7029(11) C(ll) 0.4436 (8) 0.7285(10) 0.7825(18) C(12) o·.4390(6) 0.7922(12) 0.8847(15) C (13) 0.3836(5) 0.8450(8) 0.8806(10) C.(14) 0.3524 (8) 0.9263(11) 0.9697(17) C (15) 0.2914(9) 0.9553(10) 0.9257(18) C(16) 0.2724(9) 0.9192(12) 0.8138(21) C (;t 7) 0.2948(7) 0.8480(13) 0.7316(16) C(l8) ·o.3535(5) 0.8176(9) 0.7700(13) C(l9) 0.4774(4) 0.5403(8) 1.048 (11) C(20) 0.4685(4) 0.4682(8) 0.9443(12) C(21) 0.5172(4) 0.4767(8) 0.8537(10) C(22) 0.5609(4) 0.5567(7) 0.9062(9) C (23) 0.6154(5) 0.5960(8) 0.8592(10) C (24) 0.6485(5) 0.6677(9) 0.9327(14) C(25) 0.6243(5) 0.7062(7) 1.0513(14) C(26) 0.5684(5) 0.6721(8) 1.0959(9) C (27) 0.5347(4) 0.5930 (7) 1.0258(10) C(28) 0.3052(6) 0.5900(8) 1.0840(12) C (29) 0.2998(4) 0.6387(8) 0.9691(14) C (30) 0.2948(5) 0.5696(9) 0.8638(12) C (31) 0.3117(5) 0.4692(8) 0.9175(11) C (32) 0.3228(5) 0.3640(12) 0.8573(12) C (33) 0.3378(6) 0.2805(9) 0.9385(18) C (34) 0.3448(6) 0.2926(9) 1.0700(15

92

TABLE 21--Continued

.. Atom x/a y/b z/c

C (35) 0.3373(5) 0.3909(9) 1.1307 (11) C(36) 0.3187(4) 0.4806(9) 1.0511(11) H (Cl) 0. 3102 0.8405 0.3552 H(C2) 0.4084 0.9400 0.2833 H(C3) 0.5039 0.8309 0.3076 H(C5) 0.5223 0.6053 0.4058 H (C6) 0.4628 0.4505 0.4869 H(C7) 0.3484 0.4636 0.4998 H(C8) 0.2967 0.6178 0.4498 H(ClO) 0.3928 0.6886 0.6327 H (Cll) 0.4868 0.6827 0.7653 H (C12) 0.4708 0.8026 0.9584 H(14) 0.3689 0.9572 1 .• 0577 H(C15) 0.2641 1.0044 0.9666 H(C16) 0.2289 0.9487 0.7778 8: (Cl 7) 0.2732 0. 816 4 0.6487 H (C19) 0.4480 0.5475 1.1207 H(C20) 0.4335 0.4212 0.9325 H (C21) 0.5208 0.4366 0 •. 772 3 H (C23) 0.6343 0.5735 0.7765 H(C24) 0.6890 0.7020 0. 89 32 H(C25) 0.6513 0.7548 1.1064 a·cc26 > 0.5526 0.7025 1.1767 H (C2 8) 0.3093 0.6320 1.1641 H(C29) 0.2720 0.7099 0.9540 H(C30) 0.2869 0.5846 0.7694 H(C32) 0.3213 0. 34 75 0.7637 H(C33) 0.3427 0.2051 0.9061 H (C34) 0.3584 0. 2365 1.1332 H(C35) 0.3396 0.4016 1 .• 2320

a Standard deviations in parentheses refer to last digit quoted.

~ Isotropic thermal parameters for hydrogen atoms taken 02

as 5.0 A.

93

TABLE 22

ANISOTROPIC TEMPERATURE FACTORS _a,b(x 104) FOR DIINDENYLMAGNESIUM

Atom all a22 a33 al2 al3 a23

Mg(l) 36 (1) 58 (3) 95(4) -4(2) 5 (2) .-6 (3)

Mg(2) 24(1) 59 (3) 123 (5) 0(2) 5(2) 8 ( 3)

C (1) 62(7) 86(14) 199 (27) 34(9) -40(11) -9(16)

C(2) 131(13) 38(10) 148(21) -22(10) 12 (15) -26(14)

C (3) 84(9) 79(14) 155(22) -54(9) 47(12) -49(17)

C(4) 41(5) 101(14) .112(17) 2(7) 7 (8} -45(13)

C(5) 47(6) 158(19) 231(29) 24 (10) . 1.(10) -47(22)

C(6) 124(15) 58(15) 238 (33) 29 (14) 11(25) -9(20)

C(7) 142 (18) 103(21} 192 (33) -63"(19) -16 (25) -49 (23)

C (8) 47(6) 175(20) 205(26) -54 {11) -14 (11) -41(23)

C (9) 33(5) 110(14) 124(17) -23{6) -5 (7) -37(13)

C{l0) 96(10) 112(14) 75(16) -60(10) 21(9) -18(12)

C (11) 82(9) 57(10) 267 (31) -5(8) 86 ( 13) 7(16)

C (12) 27(5) 167(19) 291(31) -35 {8) -39 (10) 163 {21)

C (13) 26(4) 55(9) 131(15) -14(5) -1 ( 7) 7(10)

C(14) 83{9) 81(16) 268(35) -31(10) 66 (18) -2(20)

C(lS) 99(9) 79(12) 222 (28) 19 (8) 102(15) 15(16)

C(16) 97(10) 102(16) 358 (38) 4 8 (10) 140(18) 96(22)

C (17) 45(6) 149(19) 278(33) -32(9) -36(12) 132(22)

C(l8) 27(4) 75(11) 178 (21) -2 3 ( 6) -22 (7) 66(13)

C(19) 21(4) 82(10) 135(17) 14 (5) 8 (7) -6 ( 13)

C(20) 25 (3) 56(8) 172(17) 1 (4) 7 ( 8) 27(12)

C (21) 22 (3) 51 (8) 126(15) 7(5) 2 (7) -4(10)

C (22) 18(3) 66(9) 78 (13) 10 (4) 7 (5) 9 (9)

94

. TABLE 22--Continued

Atom '\1 13 22 B33 13 12 13 13 13 23

C (23) 32(4) 62(9) 104(13) l(5) 9 (6) 0(10)

C(24) 35(5) 91 (12) 172(21) -3(6) 7 (9) 15(15)

C(25) 26(4) 53 (9) 206(23) . -4 ( 5) -17(9) -15(13)

C(26) 30(4) 88(11) 95 (14) 10(6) -17(7) -9 (11)

. C(27) 13(3) 73(9) 107(14) 10(4) 8(5) 10 (11)

C (28) 44(5) 56 (9) 151(19) 6 (5) 20(8) -6(12)

C(29) 24 (3) 64(10) 223 (23) 0(6) 24 (8) 30(14)

C (30) 37 (4) 75(9) 140(16) 5 (5) -20 (7) 47(10)

C (31) 26(4) 73(11) 116(19) -7(5) -3(7) -16(11)

C(32) 36(4) 151(15) 126(16) -24 ( 7) -2 (7) -30(15)

C (33) 44(5) 60 (10) 270(30) -3(6) 1 (11) . -19 (16)

C (34) 46(5) 76(12) 202(24) -6 (6) 15(10) 36 ( 15)

C (35) 39 ( 4) 89 (11) 120(16) -6 (6) . 8 ( 7) 8(11)

C(36) 19 ( 3) 107 (13) 91(15) -3 (5) 3(6) 26(12)

a Standard deviations in parentheses refer to last digit - quoted.

b Anisotropic thermal parameters defined by exp

[ 2 2 2 ] -13 11h + a22k + 13 331 + 213 12hk + 213 13hl + 213 23kl)

95

TABLE 23

OBSERVED AND CALCULATED STRUCTURE FACTOR AMPLITUDES FOR BIS(INDENYL)MAGNESIUM

UUHl• J•-• U•• l O "8.J P.I " o U~.l hl.J 6 II ~2.1 ~l. .. 8 0 ~2.7 ~1-"

lO ~ 11.7 10,<t u o 11.e u.~ I" l l,1 <t.? 22 0 lCl,!, jY, I

l I SI. 7 <,1>,6 l l liloY Ill.,~ l I 31>,U H,J " I ~h6 'iii.~ '> I <,6.Z Su,? I, I <,J,I H,·, 1 I '1,~ 11,/ ~ I h,I 16.~ 'I l 27,U l1>,~

10 I 2,,1 'I0,1> II l ,,.,2 H,~ 11 l o,2 1>,7 11 I H,l H,d 1• I ll,.., 11,1 U I 11,., IS,7 u 2 .,,.. 7.) l 2 zq,7 2<,,y l l l'l,d L',,,; 3 2 $0,1> 4~,o <, l lll,l UO,• ~ 2 11 ... Vi,\ 1, 2 )7, I J~,1, , 2 1,] ... .,

8 2 ll,o l~,l ~ l '>l,~ H,~

10 2 <,5,<, .. ~.~ II l ll, .. lh~ 12 2 11,0 ll,> u 2 ,..,,s ,..,,a H ;;: n ... 2s.o

I l '><';.6 ~"•" 2 3 ..... , .. ,.,, 3 l lu1>,<, ')5,6 <, l 1>S,l 8<,q i ) 2L,J U,\ 6 .3 b,~ It,,! I 1 <;,I I0,2 ~ l .. 1,2 42,<1

10 3 ..... 7 2<t,] 11 l l'>,4 17,1 12 l 15,1 l'>,1>

H ~ H:! H:i

'" ' . " " " " " ,, ' ' ,

11,1> IZ,J I <S,1 21,4 ~ ll,2 lv,1

,.1 a,4 ll h,O 11,7 ll ll,} l<,o H l<,,~ l~.~ \'> 20,<i ,1 ... I'< ll," <;,~

" 16,0 lo,~ S ,~.5 9,<, 6 I.J

" " " " .. " ' ,

' " " " " .. " ' ' '

' " ' .. ''" 't lll

, " '" " " l~ Iii

'" " " , " " ,l It

'" " 11 It

If,~ 15.7 .. , H.<, 1a.q u.1 11.1 ,., ~Col .. , l2o2 ho<> 22o2 ,., 11.J 1~. ~ ho2 22. l 2loh

, .. 41oZ n..i

l0.2 1z.,, l1o1 l«o'J IB.J ,., ,., 1,.~ l<ol

1s.1 2~.• 14.~ !<>.~ ll,7 1'.-J

II.I ~o<> 3,l

lJ.5 ll.2 1,1 ,.,

'"·" 1 .... 1 ... ,, It.~ H.l 1,.,; Doij

7,l' l '•" l•J.,.

3 U ti,/ 13d UUOL• lh .. ou l O lbd ~3.1 2 0 , ... •;.:i l O 4d, d >4o4 't J lv'i•~ <. H.~ 5 ~ I~.• I 'lou 6 •'.! <,]..; 7 3•,.1 a o 15,> II.I q 'lh.3 H,~

\LI <) ~.,;

ll [) ~. I 3,'J It ) ~•.' ~•,.-l l~ 4.1 l,• 16 ~ ,.., •• , :i .. , 22 J. ~ 1, <>

0 I "" I.~ I t 11,.1 Uld , 3 I D.• lJ•'

I 14.z lo.,•

. ' l •I•<

' ' I hol 1,., llol ' IU I >I.I

ll I 1,,,4

" ' ll I I~-.< ·~-" n ... lJ,, <o7.<• .,,,.1

L4 I I,!.~ I'> I 11.l 0 }. l,;,,

' . 'I• I ;,,.,,

5 2 -~--

J'I•"

""·~ -1.~ ,il.5 ~,.~ ?S • ., ' ' '

<b,0 -~. ~ ,'l,..,

10 2 "•~ ~- 1 II i J\.'l 2''•'' 12 2 ,~.I J·••• H 2 "•2 1,,.2 I • l l 1.~ 11., n z 12., 1,.~ 1 .. 2 1,.1 n 2 lJ.l 7.J

0 ~l.l Oh~ I h~.,; ~"•" 2 I l~., l7,I

• I \n, 1 10~ •'• 't l 4~,4 4'>.o '> ) '>~, I ~l. f

3 v.1 19., 7 l l'>o 1 2~. t ~ 3 \~.J IS.~

4, 7 ].~ 10 11.7 H.'1 U Ho<> l~.4 u H.'I ~o.l 1.. 11.1 10.n

0 h,9 ~.1 I U,5 l'l,J i l~. 1 ll,l ) ld,l l4.·, 4 ~l. l ~l,,J ~ H,l H,'J

B.<; ~l..l 1 1~.1 19.4 ,j 440,J 4l.~ 9 u.~ ZJ.J

10 lbo5 28,0 II o.~ do<l 12 If,<, h.~ 14 LS.3 H,9 lb I I.~ 17.~ 21 IU.d l.3

0 ~., ,. , I U.,J llo'I 2 ll,f 11.0

,

' " " " u ..

0

' ' ' . , ' " " " ,. " ' ' ' ' . ' "' " " " .. ' ' ' . . ' " " .. '

16.1 14.'l u.o 21,l 44.1 H.~ lJol l~.L 41o<l 4Cd 30.9 2·,.1 2,.0 n.~

8oh 6.~ 1.4 ,.~

14,U 14.l llo1 U.J lloR lt,,P. 22.8 lilo<o Hob 61,b '04.'I u.o B.4 ~,l.t 10.9 !Bob 1•1., 11.1 20.; l1os B,'I ~hi z~o~ z~.1 U..~ Hob \a,4 17.l 'lob llo4

Jl.l II.'> .•.~ 4., )~.~ J1.1 1s.1 14.z H.~ 11,il 10.~ ~., l~•I Hob 11.2 l~.b H.2 14.~ lo.~ H.<> 10.1 ~., 11,'1 11,7 ,.4 b,'1 1'1, t lJ.? 30.4 J'I.J !O.l ~. 7 ll,4 d,I lid !~.~ 9.o e.2

L~.l 1~.o tu.I ll,J , .. \0.d ll., 12.t \].<; J0.8 !(',., ll.~ ho1 10,9 29,o D,? 14.7 z~.~ l '!, I ,.,

3.3 .',] l~. 7 I,.~ b.~ H,:>

~ ts. 7 17. I ll o.t ~.,,

~: f ;: ; ~ !:~ I 'I 10,4 ~.~

I IV IJ.I H.J J 1;, 11.c n.·, 4 ,., n., 5 t,J a.o e.l

1,1 11.~ J].,l 1 I~ Is,•; \'lo\

IJ ;; 1<,f 74.4 II ll,'• 14.I

2 ll U.I U •. , ) 11 , •• ,

II ,n.,, 2J,I 11 11 u.l ~.~

ll O.J ;.1 2 i< 11.1 J,:.\ I Ll ~. ~ ~.~

J lJ Jd ••" / JI ,., lv.1 ...... ,. 7 ....... 'J '> l 7l.4 l"'J.l l ~ IJ,.7 !'..:.,, 2 J H." J4 0 J , J ~4. I ~< .•;

' " " ..

41.'J 4<,.7

~"-" 2'1. • 11.1 2~., n.,

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97

Fig. 9.--Illustration of magnesium(l) and its associated inderiyl rings.

98

99

Fig. 10.--View of magnesium(2) and its associated indenyl rings.

100

101

Figures 9, 10, and 11 each magnesium atom is coordina­

ated to three indenyl moieties, one in a penta-hapto fas~ion

and two in a less symmetric manner. The substance exists

therefore in an -infinite polymeric arrangement with both

bridging and terminal indenyl groups.

Table 24 presents the bond length calculations upon

which a detailed description of the structure can be based.

The terminal group is bonded to Mg(l) at distances ranging

0

from 2.31(1) to 2.54(1) A with the larger values correspond-

ing to the sterically less favorable C(4) and C(9) positions.

The association with the two bridging ring systems appears to

be through essentially only one carbon atom in each group:

0 0

C(lO) at 2.26(1) A and C(21) at 2.32(1) A. The extent to

which the interaction is localized with these two atoms is

seen with reference to the other distances in the five-

membered ring fragments (Figure 12). The closest approach 0

by another atom from either ring is 2.67(1) A, greater than

any approach for the penta-hapto group.

The second independent magnesium atom, Mg(2), is

bonded to its terminal group in a more distorted fashion than 0

is Mg(l); the lengths range from 2.26(1} to 2.60(1) A, but

again the long distances correspond to the sterically less

102

Fig. 11.--Structure and unit cell packing of bis(indenyl)magnesium.

103

104

TABLE 24 ·o

INTERATOMIC DISTANCES (A) AND ANGLES (DEG) FOR DIINDENYLMAGNESIUM

Bonded

Mg(l)-C(l) 2.46(2) Mg(l)-C(2) 2.31(1) Mg(l)-C(3) 2.35(1) Mg(l)-C(4) 2.45(1) Mg(l)-C(9) 2.54(1) C(l)-C(2) 1.38(2) C(2)-C(3) 1.37(2) C(3}-C(4) 1.41(2) C (4) -C (5) 1.44(2) C(5)-C(6) 1.41(2) C(6)-C(7) 1.29 (3) .c (7) -c (8) 1.32(2) C(8)-C(9) 1.42(2) C(9}-C(l) 1.44(2) Mg(l)-C(l0) 2.26(1) Mg (1) -C (11) 2 .• 93(2) Mg(l)-C}l2) 3.65(2) Mg(l)-C(l3) 3.63(1) Mg (1) -C (18) 2. 84 (1) C(l0)-C(ll) 1. 34 (2) C(ll)-C(l2) 1.33(2) C(12)~C(l3) 1.36(2) C(13)-C(14) 1.52(2) C(14)-C(15) 1.43(2) C(15)-C(16) 1.31(3) C(16-C(17) 1.32(2) C(17)-C(18) 1.38(2) C(l8)-C(10) 1.52(2) Mg(2)-C(19) 2.33(1) Mg(2)-C(20) 2.46(1) Mg (2) -C (21) 3.32(1) Mg(2)-C(22) 3.70(1) Mg(2)-C(27): 3.18(1) C(19)-C(20) 1.41(1) C(20)-C(21) 1.41(1) C(21)-C(22) 1.47(1) C (22)-C (23) 1.36(1) C(23)-C(24) 1.37(1) C(24)-C(25) 1.42(2) C(25)-C(26) 1.36(1) C(26)-C(27) 1.42(1) C(27)-C(19) 1.41(1) Mg ( 2 ) -C ( 2 8 ) -· 2.43(1) Mg(2)-C(29) 2.26(1) Mg(2)-C(30) 2.34(1) Mg ( 2 ) -C ( 31) 2.55(1) Mg (2) -C ( 36) 2.60(1) C(28)-C(29} · 1.38(2) C ( 2 9 ) -C ( 3 0 } 1.39(2) C(30}-C(31) 1.41(1) C(31)-C(32) 1.46(2) C ( 3 2) -C ( 3 3) 1.37(2) C (33)-C (34) 1.38(2) C(34)-C(35) 1.38(2) C(35)-C(36) 1.44(2) C(36)-C(28) 1.43(1) Mg(2)-C(ll) 2.40(1) Mg(2)-C(12) 2.44(1)

0

Nonbonded Distances (A)

Mg (1) -C (5) 3.42(2) Mg (1)-C (8) 3.53(1) Mg (1) -C (17) 3.41(2) Mg(2)-C(l0) 2.87(1) Mg ( 2 ) -C ( 13 ) 2.88(1) Mg(2)-C(l8) 3.16(1) Mg(2)-C(32) 3.60(1) Mg(2)-C(35} 3.64(1)

TABLE 24--Continued

0

Nonbonded Distances (A}

Mg(2}-C(l4} C(5)-C(10} C(6}-C(l0} C(8)-C(10) C(10}-C(30} C (11) -C (22) . C(ll)-C(27) C(ll)-C(l9) C(ll)-C(29) · C (12) -C (19) C(12)-C(26) C(13)-C(30) C(l5}-C(29) C(l7)-C(29) C (18) -C (29) C(l9)-C(36) C(l9)-C(28) C ( 2 0) -C ( 31) C(20)-C(32) C(20)-C(33) C(20)-C(34)

3.92(2) 3.79(2) 3.79(2) ~.33(2) 3.41(2) 3.54(2) 3.61(2) 3.68(2) 3.99(2) 3.64(2) 3.84(2) 3.91(2) 3.94(2) 3.58(2) 3.32(2) 3.49(1) 3.77(2) 3.38(1) 3.51(2) 3.65(2) 3.67(2)

C(l)-C(lO) C(4)-C(10) C(7)-C(l0) C(9)-C(10) C(10)-C(29) C(ll)-C(21) C(ll)-C(20) C(ll}-C(30) C(12}-C(27) C(l2}-C(29) C(12}-C(22) C(l3)-C(29) C(14)-C(29) C (16)-C (29) C(17}-C(30) C(18}-C(30) C(l9)-C(35) C(19)-C(31) C(20)-C(35) C(20)-C(35)

Bond Angles

C(l)-C(2}-C(3) C(3)-C(4)-C(9) C(9)-C(l)-C(2) C(4}-C(5)-C(6) C(6)-C(7)-C(8) C ( 8) -C ( 9 ) -C ( 4)

C(10)-C(ll)-C(l2) C(l2)-C(13)-C(l8) C(18)-C(l3)-C(l4) C(14)-C(15)-C(l6) C(16)-C(l7)-C(18) C(27)-C(l9)-C(20) C(20)-C(21)-C(22) C(22)-C(27)-C(19) C(22)-C{23)-C(24)

112.4(10) ·108.1(13) 104.4(13) 118.4(14) 122.9(17) 120.1(14) 113.5(15) 108.9(13) 117.9(13) 118.9(16) 109.3(18) 106.4(10) 106. 0 .( 9) 109.9(10) 118.6(11)

C ( 2) -C ( 3) -C ( 4)

C (4)-C (9)-C (1)

C(9)-C(4)-C(5) C(5)-C(6)-C(7) C ( 7 ) -C ( 8 ) -C ( 9 ) C(18)-C(10)-C(ll) C{ll)-C(l2)-C(13) C(l3)-C(18)-C(10) C(l3)-C(l4)-C(15) C(l5)-C(16)-C(17) C(l7)-C(18)-c(l3) C(l9)-C(20)-C(21) C{21)-C(22)-C(27) C(27)-C(22)-C{23) C(23)-C(24)-C(25)

105

3.81(2) 3.50 (2) 3.57(2) 3~26(2) 3.76(2) 3.57(2)

. 3.67(2) 3.85(2) 3.53(2) 3.83(2) 3.92(2) 3.38(1) 3.80(2) 3.84(2) 3.71(2) 3.46(2) 3.64(2) 3.91(2) 3.41(2) 3.55(2)

106.7(13) 108.4(12) 119. 0 (14) 119. 7 (16) 119.8(16) 1_02. 4 (11) 108.9(14) 106.1(12) 112.0(15) 133. 5 (21) 127.8(16) 111.2(9) 106.3(9) 122.5 (10) 120.8(11)

C(24}-C(25}-C(26} C(26}-C(27}-C(22} C(28}-C(29}-C(30} C(30}-C(31)-C(36} C(36}-C(31)-C(32} .c ( 3 2) -c ( 3 3) -c ( 3 4) C(34)-C(35}-C(36)

TABLE 24--Continued

Bond Angles

121.0(11} · 117.3(9) 113.2(9) 109.3(11}

. 119. 7(12) 123.5(13) 116.7(12)

C(25)-C(26)-C(27) C(36)-C(28)-C(29) C(29)-C(30)-C(31). C(31)-C(36)-C(28) C(31)-C(32)-C(33) C(33)~C(34)-C(35) C(35)-C(36)-C(31)

106

119.6(11) 104. 9 (11) 104.5(10) 108.1(11) 116.3(12) 122.3(13) 121.3(12)

107

Fig. 12.--Bond distances and angles within the indenyl groups for Mg(C9H7) 2 .

..... 0 00

109

favorable C(31) and C(36) positions. In this situation the

bridging groups are coordinated through two carbon atoms

0

2.33(1) to 2~46(1) A.

This is only the second single-crystal study of a

n-c5a5 group being coordinated to the magnesium. Stucky

0

has an average Mg-n-C distance of 2.55 A, whereas in

bis (indenyl) magnesium an average Mg-n-C distance of only

0

2.43 A is found (Table '24).

The normal magnesium-carbon single bond is about

0

2.18 A (76, 77). Thus, it is seen that the bridge bonds are

longer than normal single bonds, but shorter than then-bonds

0

(2.43 A).

We view the bonding as being either essentially ionic

with some directional {covalent) character or weak covalent

bonds, such that the lattice,effects (packing) dominates.

Such is not the case with diindenyliron where the strong

covalent bonds cannot be broken even for more desirable

packing.

For each ring the results of least-squares best-

plane calculations are shown in Table 25. The maximum

0

deviation in any case is 0.04 A from the plane indicating

110

planarity of the groups. Figure 12 shows the bond lengths

and angles in the four indenyl moieties. The average carbon­

carbon bopd distance is well within the expected range (45).

It should be noted that the bridging indenyl groups do not

differ significantly from the terminal group with respect

to either bond distance of angles and, within the group

itself, no unusual variations are found.

Plane

Mgl-Ring 1

Mgl-Ring 1

Mgl-Ring 2

Mgl-Ring 2

Mg2-Ring 3

Mg2-Ring 3

Mg2-Ring 4

f.ig2-Ring 4

TABLE 25

BE.ST WEIGHTED LEAST-SQUARES PLANES FOR

DIINDENYLMAGNESIUM

-0.1018x - 0.3210y - 0.9416z + 7.4862

-0.0989x - 0.3299y - 0.9397z + 7.4587

0.4484x + 0.7440y - 0.4953z - 6.6593

0.428sx + 0.7558y - 0.4952z - 6.8951

-0.4900x + 0.7232y - 0.4868z + 5.5100

-0.4814x + 0.7317y - 0.4825z + 5.3167

0.9619x + 0.2442y - 0.1232z - 6.6971

0.9642x + 0.2322y - 0.1283z - 6.5799

0

Deviations of Atoms from Planes (A)

=

=

=

=

=

=

--=

Atom Mgl-Ring 1 Atom Mgl-Ring

Cl -0.00 ClO -0.00 C2 -0.00 Cll -0.00 C3 0.01 Cl2 0.01 C4 -0 .01 Cl3 -0.01

0

0

0

0

0

0

0

0

2

I

111

TABLE 25--Continued

Atom Mgl-Ring 1 Atom Mgl-Ring 2 I C9 0.01 Cl8 0.01 I Mgl -2 .10 Mgl 2.14 Cl -0.02 ClO -o.oo C2 -0.01 Cll -0.02 C3 0.02 Cl2 o.oo C4 0.00 Cl3 0.01 cs 0.01 Cl4 0.04 C6 o.oo ClS 0.02 C7 -0.03 Cl6 -0.04 ca -o.oo Cl7 o· .02 C9 0.02 Cl8 -0.02 Mgl -2.10 Mgl 2.14

Atom. Mg2-Ring 3 Atom Mg2-Ring 4

Cl9 0.01 C28 0.01 C20 -0.01 C29 -0.01 C21 0.01 C30 0.01 C22 -o.oo C31 -0.01 C27 -0.01 C36 -o.oo Mg2 2.14 Mg2 2.10 Cl9 0.01 C28 -0.00 C20 -0.03 C29 -0.03 C21 -0.00 C30 0.02 C22 0 .• 01 C31 0.01 C23 · o .01 · C32 0.01 C24 0.03 C33 0.01 C25 -0.03 C34 -0.02 C26 -0.02 C35 -0.02 C27 0.02 C36 0.03 Mg2 2.12 Mg2 2.09

CHAPTER IV

CONCLUSIONS

From our studies of the preparation and properties

of organoscandium compounds we have presented evidence for:

1. The solid state existence of two types of

scandium-carbon bonds, one of the classic

~-description and one which could be viewed

as a in character. The normal Sc--C ~-bond

is 2.48 A, and the a-bond lengths are closely

similar.

2. The existence of some degree of directional

covalent bonding in the series Sc, Yt, La

Lu.

3. The use of Mg(C9H7) 2 as an intermediate in the

preparation of new organoscandium compounds.

4. The "normal" values of Sc-Cl and Sc-0 bond

l h d .. . d' f 3+ engt s an ionic ra ius o Sc

The structural studies described herein represent

the first detailed characterization of organometallic

112

113

scandium complexes. We expect that based on this work as a

foundation, the field of scandium chemistry will grow and

perhaps even develop in the fashion of titanium chemisty.

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