Journal of Crystallographic and Spectroscopic Research, Vol. 16, No. 4, 1986

Crystal and molecular structure of N-(2- morpholinoethyl)-2-oximato-l-phenylpropan-1-

iminechloropalladium(II)

KOLA A. AKINADE, A. ADEYEMO, and RAY J. BUTCHER* Chemistry Department, Howard University

Washington D. C. 20059

and

E. SINN* Chemistry Department, University of Virginia

Charlottesville, Virginia 22901

(Received October 28, 1985)

Abstract

The crystal structure of N-(2-morpholinoethyl)-2-oximato-l-phenylpropan-1- iminechloropalladium(II), [Pd(L)C1], has been determined from X-ray data col- lected by counter methods. The compound crystallizes in the orthorhombic space group Pna21 with four molecules per unit cell, the dimensions of which are a = 9.602(2), b = 8.150(1), c -= 21.181(4) .~. Full matrix least-squares refine- ment gave a final R value of 0.042 for the 3218 independent observed reflec- tions. The oxime ligand is deprotonated and is acting as a tridentate ligand coordinating to the palladium through the oxime nitrogen, the imine nitrogen, and the tertiary amine nitrogen of the morpholine moiety. To complete four- coordination about the palladium atom, a chloride ion is also attached to the central metal atom. The donor atoms plus the palladium atom are planar.

Introduct ion

Recently some of us have reported the synthesis and structural character- ization of a dimeric diamagnetic complex of copper(II) formed with the title

597

0277-8068/86/0800-0597505.00/0 �9 1986 Plenum Publishing Corporation

598 Akinade et al.

ligand (Akinade et al., 1982). As part of a continuing investigation of the co- ordination behavior of oxime-type ligands (Butcher et al., 1979, 1981), a palla- dium complex of the same ligand was prepared in order to compare and contrast the coordination behavior of this metal and copper(II), both of which prefer a square-planar four-coordinate environment. Additionally, there has been recent interest in the structural chemistry of bidentate oxime and dioxime complexes of palladium(II) (Rundle et al., 1959; Calleri et al., 1967; Tanimura et al., 1967; Kitano et al., 1971; Mawby and Pringle, 1971; Fallon and Gatehouse, 1976; Hussain and Schlemper, 1979; Constable et al., 1980; Endres, 1980; Ma et al., 1980; Ma and Angelici, 1980; Endres and Weiss, 1981; Constable et al., 1983). In these compounds there are two types of oxime coordinated to palladium: parent and deprotonated oximes. From a comparison of the bond lengths and angles found in these palladium oxime complexes it is possible to tell whether or not the oxime group has been deprotonated upon coordination. The key indicator appears to be the length of the oxime N-O bond. In the parent

o

oxime it has an average bond length ca. 1.40 A, while in the deprotonated oxime it is considerably shorter at ca. 1.33 ,h,. In this study the mode of co- ordination of the potentially tridentate amine oxime ligand is determined and compared with that of copper binuclear and trinuclear complexes derived from this ligand and other analogous amine oxime ligands. Line diagrams of the three types of structures are shown in Fig. 1.

E x p e r i m e n t a l

The potentially tridentate amine oxime ligand, LH, was prepared by a Schiff base condensation of 1-phenylpropane-l,2-dionemonooxime with N-2-amino- ethylmorpholine in methanol to obtain a bright yellow crystalline precipitate. The title compound was then prepared by refluxing together KzPdC14 and LH in an aqueous methanol solution with a stoichiometric amount of piperidine present as base. The clear yellow solution obtained deposited bright yellow crystals over a period of several days. From this batch a regularly shaped crystal was chosen for X-ray analysis.

Cell dimensions, space group data, and intensity data were obtained by standard methods (Storm et al. , 1983) on a Nicolet P3m microprocessor con- trolled four-circle diffractometer."

Crystallographic data: C15H20N3OzC1Pd, M = 452, orthorhombic, a = 9.602(2), b = 8.150(1), c = 21.181(4) ]k, V = 1658 ~3, Z = 4, density = 1.79 g cm -3, #(Mo Kot) = 14.3 cm -1.

The systematic absences Okl, k + l = 2n + 1, and hOl, h = 2n + 1, identify the space group as either Pna21 (33 in International Tables, Vol I,

Structure of C15Hz0N3OzCIPd 599

c, J

(a)

Co)

(c)

Fig. 1. Line diagram of title complex (a), typical binuclear complex (b), and typical tfinuclear complex (c).

C9v) or a nonstandard setting of Pnma (62 in International Tables, 16 D2h ) . Space group Pna21 proved to be the correct choice as the structure could only be solved and refined in this space group.

The 0-20 scan technique was used to record the intensities for all non- equivalent reflections for which 4 < 20 < 60 ~ The required scan widths were

600 Akinade et al.

determined from an examination of the peak profiles of several low-angle re- flections. From this it was determined that a scan width of 0.6 ~ above and below Kc~ and Kc~ 2 was sufficient.

The intensities of three standard reflections showed no greater fluctuations during data collection than those expected from Poisson statistics. The raw in- tensity data were corrected for Lorentz-polarization effects and absorption. Of the 6318 measured intensities, there were 3218 with F 2 > 3a(F2o), where a(F2o) was estimated from counting statistics (Corfield et al., 1967). These data were used in the final refinement of the structural parameters.

The structure was solved by the heavy-atom method. From a three-dimen- sional Patterson synthesis the positions of the palladium and chloride atoms were obtained, and refined. From this the data were sufficiently well phased to permit the location of the remaining nonhydrogen atoms from difference Fourier syntheses. All programs, scattering factors, and general procedures are those outlined in Freyberg et al. (1976). Anisotropic temperature factors were intro- duced for the palladium and chlorine atoms; methylene and phenyl hydrogen atoms were inserted in their calculated positions, but methyl hydrogen atoms were not included as they could not be located in a difference Fourier synthesis nor could they be calculated. The hydrogen positional parameters were included in the calculation for two cycles of refinement and then held fixed, while their thermal parameters were fixed.

The model converged with R = 0.042 and Rw = 0.045. A final difference Fourier synthesis was featureless.

R e s u l t s a n d D i s c u s s i o n

Final positional (and thermal) parameters are given in Table 1. Table 2 contains the most important bond lengths and nearest intermolecular contacts, Table 3 contains the bond angles, while Table 4 compares selected bond lengths and bond angles with those of other palladium oxime complexes. The digits in parentheses in the tables are the estimated standard deviations in the least sig- nificant figures quoted, and were derived from the inverse matrix in the course of the least-squares refinement calculations. Figure 2a is a scale diagram of the molecule, while Fig. 2b shows the molecular packing in the unit cell.

As is evident from the packing diagram, the structure consists of relatively isolated complex molecules, with the closest intermolecular contacts being 3.055(7) A between the oxime oxy.gen atom and C(5). The nearest intermo- lecular Pd-C1 distance is 4.366(4) A while the nearest Pd-Pd intermolecular distance is 4.802(3) .A, indicating little, if any, stacking interactions between molecules as is evident in many other palladium oxime complexes (Endres,

Structure of C15He0N3OzCIPd

Table 1. Positional parameters

Atom x y z

Pd 0.77599(9) 0.7448(2) 0.2500(0) C1 0.8755(4) 0.9500(5) 0.1874(2) O 0.672(1) 1.047(1) 0.3109(5) O(17) 0.929(1) 0.422(2) 0.0724(5) N(1) 0.683(1) 0.890(2) 0.3147(6) N(4) 0.696(1) 0.585(1) 0.3053(5) N(7) 0.836(1) 0.539(2) 0.1969(5) C(2) 0.623(2) 0.811 (2) 0.3622(7) C(3) 0.634(1) 0.635(2) 0.3553(6) C(5) 0.711 (2) 0.412(2) 0.2840(7) C(6) 0.831(2) 0.398(2) 0.2434(9) C(8) 0.548(2) 0.907(2) 0.4130(7) C(9) 0.576(1) 0.526(2) 0.4054(6) C(10) 0.465(2) 0.423(2) 0.3928(7) C(11) 0.410(2) 0.315(2) 0.4373(8) C(12) 0.460(2) 0.322(3) 0.4959(9) C(13) 0.570(2) 0.416(3) 0.5130(8) C(14) 0.629(2) 0.524(2) 0.4656(7) C(15) 0.986(2) 0.553(2) 0.1723(8) C(16) 1.022(2) 0.419(3) 0.1207(8) C(18) 0.801(2) 0.393(2) 0.0925(8) C(19) 0.748(1) 0.525(2) 0.1386(7) H(51 ) 0,71 (2) 0.33 (2) 0.318(9) H(52) 0~63(2) 0.39(2) 0.264(8) H(61) 0.83(2) 0.28(3) 0.226(7) H(62) 0.92(2) 0.40(2) 0.272(7) H(10) 0.43(2) 0.43(3) 0.351(8) H(11) 0.33(2) 0.24(3) 0.428(7) H(12) 0.41(2) 0.24(3) 0.527(7) H(13) 0.61(2) 0.40(3) 0.555(8) H(14) 0.71(2) 0.60(2) 0.478(7) H(151) 1.05(2) 0.56(2) 0.213(7) H(152) 1.00(2) 0.66(3) 0.154(8) H(161) 1.02(2) 0.31(3) 0.143(8) H(162) 1.12(2) 0.44(3) 0.105(8) H(181) 0.74(2) 0.39(3) 0.054(8) H(182) 0.80(2) 0.29(2) 0.112(8) H(191) 0.66(2) 0.51(2) 0.154(7) H(192) 0.75(2) 0.64(2) 0.118(8)

601

1980; Endres et al . , 1981) where intermolecular distances of 3.3 A or less are commonly found.

Contrasting dramatically with this are the Cu(II) complexes of related ox- ime ligands, which are binuclear (Butcher et al . , 1979; Akinade et al. , 1982) or trinuclear (Butcher et al . , 1981). In each type of copper complex, the oxime moiety is deprotonated and span two metal atoms to provide C u - O - N - C u bridges. The binuclear complexes contain two such bridges to form a central

602 Akinade et al.

Table 2. Bond lengths and selected intermolecular contacts (A)

Pd-Cl 2.338(2) C(9)-C(I0) 1.389(7) Pd-N(1) 2.018(4) C(10)-C(11) 1.391 (7) Pd-N(4) 1.913(4) C(l 1)-C(12) 1.330(8) Pd-N(7) 2.100(4) C(12)-C(13) 1.359(7) O(17)-C(16) 1.354(6) C(13)-C(14) 1.453(7) O(17)-C(18) 1.326(6) C(15)-C(16) 1.582(7) N(1)-O 1.287(5) C(18)-C(19) 1.541(6) N(1)-C(2) 1.325(6) (C-H) 0.99 N(4)-C(3) 1.276(5) O-C(5) 3.055(7) a N(4)-C(5) 1.492(5) O-C(10) 3.313(7) b N(7)-C(6) 1.512(8) Pd-Pd 4.802(3) b'C N(7)-C(15) 1.535(6) Pd-C1 4.366(4) c N(7)-C(19) 1.496(5) C(2)-C(3) 1.449(6) Symmetry transformations: C(2)-C(8) 1.506(6) a x, y + 1, z C(3)-C(9) 1.492(6) b �89 + x, 3 _ y, z C(5)-C(6) 1.442(6) C x - �89 ~ - y, z

Table 3. Bond angles (deg)

C1-Pd-N(t) 98.5(2) N(1)-C(2)-C(8) 120.1(6) C1-Pd-N(4) 176 .7 (2 ) C(3)-C(2)-C(8) 128.4(7) C1-Pd-N(7) 99.0(2) N(4)-C(3)-C(2) 115.8(7) N(1)-Pd-N(4) 78.6(2) N(4)-C(3)-C(9) 124.9(6) N(1)-Pd-N(7) 162 .2 (3 ) C(2)-C(3)-C(9) 119.2(6) N(4)-Pd-N(7) 84.0(3) N(4)-C(5)-C(6) 109.6(6) C(16)-O(17)-C(18) 111 .3 (6 ) N(7)-C(6)-C(5) 110.6(6) Pd-N(1)-O 125 .1 (5 ) C(3)-C(9)-C(10) 120.9(6) Pd-N(1)-C(2) 115 .4 (5 ) C(3)-C(9)-C(14) 122.0(6) O-N(1)-C(2) 119 .4 (6 ) C(10)-C(9)-C(14) 117.2(6) Pd-N(4)-C(3) 118.6(5) C(9)-C( 10)-C(11) 122.9(7) Pd-N(4)-C(5) 114 .6 (4 ) C(10)-C(11)-C(12) 118.3(8) C(3)-N(4)-C(5) 126 .8 (5 ) C(11)-C(12)-C(13) 123.3(8) Pd-N(7)-C(6) 104 .4 (4 ) C(12)-C(13)-C(14) 117.7(7) Pd-N(7)-C(15) 112 .2 (5 ) C(9)-C(14)-C(13) 120.3(7) Pd-N(7)-C(19) 110 .5 (4 ) N(7)-C(15)-C(16) t 12.9(7) C(6)-N(7)-C(19) 107 .6 (5 ) O(17)-C(16)-C(15) 111.6(7) C(6)-N(7)-C(15) 117 .8 (6 ) O(17)-C(18)-C(19) 112.6(7) C(15)-N(7)-C(19) 104 .5 (5 ) N(7)-C(19)-C(18) 113.0(6) N(1)-C(2)-C(3) 111.4(7)

s ix-membered ( C u - O - N ) 2 ring. which, within experimental error, is planar, while the trinuclear complexes have one C u - O - N - C u bridge plus e i ther a C u - O - C u or a C u - O H - C u bridge between each copper atom.

The coordination geometry about the pal ladium atom in [Pd(L)C1] is very nearly planar with the main deviat ions from planarity being caused by the re- duced bite of the five membered N ( 1 ) - C ( 2 ) - C ( 3 ) - N ( 4 ) - P d moiety [the angle

S t r u c t u r e o f C l s H 2 o N 3 0 2 C l P d 6 0 3

Table 4. Comparison of bond lengths (A) and angles (deg) in palladium-oxime moieties

Structure Pd-CI Pd-N N-O C-N Pd-N-C Pd-N-O C-N-O

2.24 a 2.08 1.42 b 1.29 126 123 111 2 2.439(9) 2.10(2) 1.39(3) b 1.28(3) 126.3(9) 117.8(9) 115.8(14)

2.405(8) c 2.449(7) c

3 - - 1.99(2) 1.40(2) d 1.27(3) 118.9(14) 119.9(12) 119.0(17) - - 1.99(2) 1.39(2) d 1.30(2) 119.6(13) 121.6(11) 116.4(15)

4 - - 1.99(2) 1.33(3) e 1.31(4) f f f - - 1.37(3) e 1.31(4) Y f f

5 - - 1.957(7) 1.337(12) e 1.321(12) 115.9(7) 121.7(6) 122.1(8) - - 1.953(9) 1.384(12) e 1.273(13) 115.8(7) 122.1(6) 122.1(8)

6 - - 1.991(8) 1.277(13) ~ 1.319(16) 114.1(7) 121.3(7) 124.5(9) - - 1.958(7) 1.372(12) e 1.271(15) 117.2(7) 123.3(6) 119.4(8)

7 - - 1.96(3) 1.36(4) b 1.36(6) 128(3) 113(3) 119(3) - - 1.97(3) 1.38(4) b 1.24(6) 128(3) 116(2) 117(4) - - 1.97(3) 1.37(5) b 1.32(5) 126(3) 120(2) 111(3)

8 - - 1.968(4) 1.345(5) b 1.277(6) 118.8(3) 120.2(3) 120.9(4) - - 1.969(4) 1.360(5) d 1.279(6) 118.6(3) 120.4(3) 120.9(4)

9 2.341(1) c 1.997(4) 1.386(6) b 1.271(4) f f f 2.546(2) c 2.343(2) c 1.974(4) 1.412(6) b 1.300(7) f f f 2.534(2) c

10 - - 1.99(2) 1.40(3) e 1.29(4) 121.5(21) 120.5(17) 118.0(23) - - 2.01(3) 1.32(3) 2 1.28(4) 125.6(21) 120.0(18) 114.2(25) - - 2.00(2) 1.32(3) e 1.27(4) 121.3(19) 122.0(18) 116.6(23) - - 1.93(2) 1.33(3) e 1.30(4) 119.0(18) 123.0(18) 117.9(23) - - 1.98(2) 1.40(3) e 1.24(4) 125.7(20) 120.1(15) 114.1(24) - - 2.20(2) 1.29(3) e 1.27(4) 119.1(20) 120.6(17) 120.1(23)

11 - - 1.968(2) 1.380(4) e 1.297(4) 116.9(2) 123.0(2) 120.2(4) - - 2.021(2) 1.404(4) b 1.299(4) 116.0(2) 129.5(2) 114.3(4) - - 1.981(2) 1.348(4) e 1.305(4) 119.5(2) 124.5(2) 116.0(4) - - 2.035(2) 1.391(4) b 1.307(4) 116.2(2) 130.7(2) 112.7(4) - - 1.971(2) 1.359(4) e 1.304(4) 118.5(2) 123.5(2) 118.0(4) - - 2.029(2) 1.404(4) b 1.307(4) 115.8(2) 131.5(2) 112.3(4) - - 1.981(2) 1.383(4) ~ 1.299(4) 119.3(2) 124.1(2) 116.4(2) - - 2.038(2) 1.404(4) b 1.302(4) 117.0(2) 130.0(2) 112.1(4)

12 - - 2.001(5) 1.401(9) b 1.289(9) 127.1(4) 117.9(4) 114.9(5) - - 1,995(6) 1.405(9) b 1.302(9) 127.8(4) 118.5(4) 113.0(6) - - 2,020(6) 1.393(10) b 1.300(8) 130.8(4) 116.1(5) 113.1(6) - - 1,988(6) 1.384(8) b 1.303(7) 124.7(3) 119.0(5) 116.3(6) - - 2.028(5) 1.391(9) b 1.315(8) 129.9(4) 116.2(5) 113.6(5) - - 1.982(5) 1.326(9) d 1.320(8) 123.6(4) 116.9(5) 119.6(5)

13 2.280(1) 2.023(4) 1.406(5) b 1.276(6) 111.5(3) 136.7(4) 11.2(4) 2.307(1) 2.026(4) 1.404(6) b 1.272(6) 112.1(3) 135.9(4) 11.8(4)

14 2.328(2) 2.018(4) 1.287(5) a 1.325(6) 125.1(5) 115.4(5) 119.4(6)

aesd's not reported; boxime N-O-H; Cbridging C1 atom; aoxime N-O; enot known whether oxime in the form of N-O-H or N-O; fvalue not reported; structures (1) Tanimura et al. (1967); (2) Kitano et al. (1971); (3) Fallon and Gatehouse, (1976); (4) Williams et al. (1959); (5) Called et al. (1967); (6) Calleri et al. (1967); (7) Mawby and Pringle, (1971); (8) Hussain and Schlemper, (1979); (9) Constable et al. (1980); (10) Ma et al. (1980); (11) Endres (1980); (12) Endres and Weiss (1981); Constable et al. (1983); (14) this study.

61)4

~1~ N(4 C~

c(1'~ (a)

Akinade et al.

C ~ ~ ~ ~ 1 C(lbO~[" c(16)

~) I ~

C(8 C I~

E

Co)

Fig. 2. Molecular diagram for [PdLCI] showing atomic numbering scheme (a), and molecular packing diagram for [PdLC1] (b).

Structure of CIsH2oN302CIPd 605

subtended at Pd by N(1) and N(4) is 78.6(2) ~ and to a lesser extent that of the five-membered ring N(4)-C(5)-C(6)-N(7)-Pd [N(4)-Pd-N(7), 84.0(3)~ From the calculated least-squares mean planes it can be seen that the conjugated part of the ligand [N(1)-C(2)-C(3)-N(4)] is nearly coplanar with the plane of the donor atoms. The phenyl ring is inclined at an angle of 62.5 ~ to this plane and serves to hold neighboring metal atoms apart. This is one of the primary factors for the large Pd-Pd separation in this molecule vis-a-vis other palladium oxime structures.

From a comparison with other palladium oxime structures (see Table 4) it can be seen that bond lengths and bond angles about the palladium oxime moiety are altered when the oxime is deprotonated. The primary effect is a pronounced shortening of the N-O bond length upon deprotonation with N-O bond lengths ca. 1.3 A for the deprotonated oxime versus ca. 1.4 .~ for the oxime itself. In the present structure this trend is confirmed with a N-O bond length of 1.287(5) A, being one of the shortest N-O lengths found in a palladium oxime structure. A secondary indicator is the length of the C-N bond. When the oxime is deprotonated and the N-O bond length is reduced to ca. 1.3 A or less, the C-N bond length increases to ca. 1.33 A from 1.27 A in the parent oxime. The other parameters in the palladium oxime moiety appear to be very "sof t , " i.e., they vary over quite a wide range of values with no apparent systematic trends apart from packing effects. For instance, the Pd-N-O bond angle varies over a range from 113 to 137 ~

Acknowledgments

Acknowledgments should be made to the National Science Foundation and the Graduate School of Arts and Sciences at Howard University for funds to purchase the X-ray diffractometer and to the National Institutes of Health for partial support of this work.

References

Akinade, A., Butcher, R. J., and Sinn, E. (1982) Cryst. Struct. Commun. 11, 2063. Butcher, R. J., O'Connor, C. J., and Sinn, E. (1979) lnorg. Chem. 18, 1913. Butcher, R. J., O'Connor, C. J., and Sinn, E. (1981) Inorg. Chem. 20, 537. Called, M., Ferraris, G., and Viterbo, D. (1967) Inorg. Chim. Acta 1,297. Constable, A. G., McDonald, W. S., Dawkins, L. C., and Shaw, B. L. (1980) J. Chem. Soc.

Dalton Trans., 1992. Constable, A. G., McDonald, W. S., Odell, B., and Shaw, B. L. (1983) J. Chem. Soc. Dalton

Trans., 2509. Corfield, P. W. R., Doedens, R. J., and Ibers, J. A. (1967) lnorg. Chem. 6, 197. Enders, H (1980) Acta Crystallogr. B 36, 1347.

606 Akinade et al.

Enders, H., and Weiss, J. (1981) Acta Crystallogr. B 37, 1360. Fallon, G. D., and Gatehouse, B. M. (1976) Acta Crystallogr. B 32, 2591. Freyberg, D. P., Mockler, G. M., and Sinn, E. (1976) J. Chem. Soc. Dalton Trans., 447. Hussain, M. S., and Schlemper, E. O. (1979) Inorg. Chem. 18, 1116. International Tables for X-ray Crystallography (1965) Vol. I (Kynoch Press, Birmingham). Kitano, Y., Kajimoto, T., Kashiwagi, M., and Kinoshita, Y. (1971) J. Organomet. Chem. 33,

123. Ma, M. S., and Angelici, R. J. (1980) Inorg. Chem. 19, 363. Ma, M. S., Angelici, R. J., Powell, D., and Jacobson, R. A. (1980) lnorg. Chem. 19, 3121. Mawby, A., and Pringle, G. E. (1971) J. Inorg. Nucl. Chem. 33, 1989. Rundle, R. E., Williams, D. E., and Wohlauer, G. (1959) J. Amer. Chem. Soc. 81, 756. Storm C. B., Freeman, C. M., Butcher, R. J., Turner, A. H., Rowan, N. S., Johnson, F. O., and

Sinn, E. (1983) Inorg. Chem. 22, 678. Tanimura, M., Mizushima, T., and Kinoshita, Y. (1967) Bull. Chem. Soc. Jpn. 40, 2777. Williams, D. E., Wohlauer, G., and Rundle, R. E. (1959) J. Am. Chem. Soc. 81, 755.

British Library Lending Division Supplementary Publication No. 63031 contains 8 pages of thermal pararaeters, least-squares planes, and structure factor tables.