Wk2Coord Chem- Intro

Coordination Chemistry

Kimia Koordinasi :Kimia Koordinasi :Cabang ilmu kimia yang mempelajari tentang senyawakoordinasi

Senyawa koordinasi :Senyawa yang tersusun atas satu atom pusat (biasanyalogam atau kelompok atom seperti VO2, TiO, dll) dan ligan(sejumlah anion atau molekul netral yang mengelilingi atom(sejumlah anion atau molekul netral yang mengelilingi atom atau kelompok atom pusat tersebut)

Ditinjau dari asam-basa Lewis, atom pusat dlm senyawakoordinasi berperan sebagai asam, sedangkan ligansebagai basa Lewissebagai basa Lewis

Sif t k di i d t di dik i d iSifat senyawa koordinasi dapat diprediksi dari Sifat ion pusatnya, dan Sifat ligan Sifat ligan

Jumlah muatan kompleks ditentukan dari penjumlahan Ju a uata o p e s d te tu a da pe ju a amuatan ion pusat dan ligan yang membentuk kompleks.

Spesies kompleks dapat berupa non-ionik, kation dan anion, bergantung pada muatan penyusunnya

Why Study Transition Metals and Their C dCompounds

Many biomolecules contain transition metals that are yinvolved in the functions of these biomolecules

Vitamin B12 contains Co Hemoglobin myoglobin and cytochrome C are iron Hemoglobin, myoglobin, and cytochrome C are iron

complexes Chlorophyll is a magnesium complex

Transition metals and their compounds have many useful applications Transition metal compounds are used as pigmentsp p g

TiO2 = white PbCrO4 = yellow Fe4[Fe(CN)6]3 (prussian blue)= blue

Transition metal compounds are used in many industrial processes

To understand the uses and applications ofTo understand the uses and applications of transition metals and their compounds, we need to understand their chemistry.

Periodic TablePeriodic Table

d block transition elements

f bl k i i lf block transition elements

d-Block Transition Elements

IIIB IVB VB VIB VIIB IB IIBVIIIB

d Block Transition Elements

Sc Ti V Cr Mn Fe Co Ni Cu Zn

IIIB IVB VB VIB VIIB IB IIB

Y Zr Nb Mo Tc Ru Rh Pd Ag Cd

La Hf Ta W Re Os Ir Pt Au Hg

M t h ti ll i d d b h ll iMost have partially occupied d subshells in common oxidation states

Electronic ConfigurationsgElement Configuration

Sc [Ar]3d14s2

Ti [Ar]3d24s2[ ]V [Ar]3d34s2

Cr [Ar]3d54s1Cr [Ar]3d54s1

Mn [Ar]3d54s2

[Ar] = 1s22s22p63s23p6[ ] p p

Electronic ConfigurationsgElement Configuration

Fe [Ar] 3d64s2

Co [Ar] 3d74s2Co [Ar] 3d 4sNi [Ar] 3d84s2

C [Ar]3d104s1Cu [Ar]3d104s1

Zn [Ar]3d104s2

[Ar] = 1s22s22p63s23p6[ ] p p

Electronic Configurations of Transition Metal Ions

Electronic configuration of Fe2+

Transition Metal Ions

Electronic configuration of Fe

Fe 2e- Fe2+





Fe 2e- Fe2+[Ar]3d64s2

valence ns e-s removed first





Fe 2e- Fe2+[Ar]3d64s2 [Ar]3d6

valence ns e-s removed first





Fe 3e- Fe3+





Fe 3e- Fe3+[Ar]3d64s2

valence ns e-s removed first, then n-1 d e-s





Fe 3e- Fe3+[Ar]3d64s2 [Ar]3d5



Electronic configuration of Co3+


Electronic configuration of Co

Co 3e- Co3+





Co 3e- Co3+[Ar]3d74s2






Co 3e- Co3+[Ar]3d74s2 [Ar]3d6



Electronic configuration of Mn4+


Electronic configuration of Mn

Mn 4e-Mn4+





Mn 4e-Mn4+[Ar]3d54s2






Mn 4e-Mn4+[Ar]3d54s2 [Ar]3d3


Coordination Chemistryy Transition metals act as Lewis acids

Form complexes/complex ionsForm complexes/complex ionsFe3+(aq) + 6CN-(aq) Fe(CN)63-(aq)

Lewis acid Lewis base Complex ion

Ni2+(aq) + 6NH3(aq) Ni(NH3)62+(aq)Lewis acid Lewis base Complex ion

Complex contains central metal ion bonded to one or more molecules or anionsmolecules or anions

Lewis acid = metal = center of coordination

Lewis base = ligand = molecules/ions covalently bonded toLewis base ligand molecules/ions covalently bonded to metal in complex

Transition metals act as Lewis acids Form complexes/complex ionsForm complexes/complex ions

Fe3+(aq) + 6CN-(aq) [Fe(CN)6]3-(aq)Lewis acid Lewis base Complex ion

Ni2+(aq) + 6NH3(aq) [Ni(NH3)6]2+(aq)Lewis acid Lewis base Complex ion

Comple ith a net charge comple ionComplex with a net charge = complex ion

Complexes have distinct properties

Coordination compoundCoordination compound Compound that contains 1 or more complexes

Example Example [Co(NH3)6]Cl3 [Cu(NH3)4][PtCl4][Cu(NH3)4][PtCl4] [Pt(NH3)2Cl2]

Coordination sphereCoordination sphere Metal and ligands bound to it

Coordination number Coordination number number of donor atoms bonded to the central

metal atom or ion in the complexmetal atom or ion in the complex Most common = 4, 6 Determined by ligands Determined by ligands

Larger ligands and those that transfer substantial negative charge to metal favor lower coordination numbersnumbers

Complex charge = sum of charges h l d h li d

[Fe(CN)6]3-

on the metal and the ligands

[Fe(CN)6]

Complex charge = sum of charges h l d h li d

[Fe(CN)6]3-

on the metal and the ligands

[Fe(CN)6]

+3 6( 1)+3 6(-1)

Neutral charge of coordination compound = sum of h l li d d b l i i

[Co(NH3)6]Cl2

charges on metal, ligands, and counterbalancing ions

[Co(NH3)6]Cl2

neutral compoundp

Neutral charge of coordination compound = sum of h l li d d b l i i

[Co(NH3)6]Cl2

charges on metal, ligands, and counterbalancing ions

[Co(NH3)6]Cl2

+2 6(0)+2 6(0) 2(-1)

Classification of coordination compound

Ligands

Classification of coordination compound

Ligands classified according to the number of donor

atoms Examples

monodentate = 1 bidentate = 2 tetradentate = 4

chelating agents

hexadentate = 6 polydentate = 2 or more donor atoms

LigandsLigands

MonodentateMonodentate Examples:

H O CN- NH NO - SCN- OH- X- (halides) CO H2O, CN , NH3, NO2 , SCN , OH , X (halides), CO, O2-

Example Complexesp p [Co(NH3)6]3+

[Fe(SCN)6]3-

Ligandsg Bidentate

ExamplesExamples oxalate ion = C2O42-

ethylenediamine (en) = NH2CH2CH2NH2y ( ) 2 2 2 2 ortho-phenanthroline (o-phen)

Example Complexesp p [Co(en)3]3+

[Cr(C2O4)3]3-

[Fe(NH3)4(o-phen)]3+

Ligandsgoxalate ion ethylenediamine

O O 2- CH2 CH2CC

O O

CH2H2N

CH2NH2* *O O

CHortho-phenanthroline

* **

*N CH CHCHN CD A

** CH

CHHC

HCN

CC

C

C

Donor Atoms

CHCH

LigandsLigandsoxalate ion ethylenediamine

CH

CC

OM

M NM N

LigandsLigands

LigandsLigands

HexadentateHexadentate ethylenediaminetetraacetate (EDTA) =

(O2CCH2)2N(CH2)2N(CH2CO2)24-(O2CCH2)2N(CH2)2N(CH2CO2)2 Example Complexes

[Fe(EDTA)]-1[Fe(EDTA)] [Co(EDTA)]-1

Ligands

EDTA

Ligands

CH2C CH2 C

OO

O O

EDTA

* *CH2N

CH2CCH2 N

CH2 CO O* ***

CH2C CH2 C

OO

OO* *

OO

Donor AtomsDonor Atoms

LigandsEDTA

LigandsO

H

C

H

C

NM

NM

LigandsEDTA

Common Geometries of Complexes

Coordination Number Geometryy

22

Linear

Common Geometries of Complexes

Coordination Number Geometryy

22

LinearExample: [Ag(NH3)2]+

Common Geometries of ComplexesCoordination Number Geometry

44tetrahedral(most common)(most common)

square planarsquare planar(characteristic of metal ions with 8 d e-s)


44tetrahedral

Examples: [Zn(NH3)4]2+, [FeCl4]-

square planarsquare planarExample: [Ni(CN)4]2-


66

octahedral


66

Examples: [Co(CN)6]3-, [Fe(en)3]3+

octahedral

Porphyrin, an important chelating agent found inchelating agent found in

nature

N

NH NH

N

Metalloporphyrin

N2+

N NFe2+

N

Myoglobin, a protein that stores O2 in cells 2

Coordination Environment of Fe2+ in Oxymyoglobin and Oxyhemoglobiny y g y g

Ferrichrome (Involved in Fe transport in bacteria)bacteria)

Berdasarkan pada jenis ikatan koordinasi yang terbentuk ligan dapat dikelompokkan sebagai :terbentuk, ligan dapat dikelompokkan sebagai :-Ligan yg tdk punya elektron yang sesuai untukikatan dan orbital kosong shg ikatan yangikatan dan orbital kosong shg ikatan yang terbentuk hanya , seperti H-, NH3, SO32- atauRNH22-Ligan yang memiliki 2 atau 3 pasang elektronnonbonding,seperti N3-, O2-, F-, Cl-, Br-, I-, OH-, S2-, g p 3NH2-, H2O, R2S, R2O dan NH2-Ligan yg memiliki orbital -anti ikatan kosongdgn energi rendah dapat menerima elektron ygorientasinya sesuai dari logam spt CO, R3P, R3As, B I CN dBr-, I-, CN-, py dan acac

- Ligan yg tidak ada pasangan elektron nonbonding nya tetapiiliki l kt ik t ti lk lki b dmemiliki elektron ikatan-, seperti alkena, alkina, benzena dan

anion siklopentadienil- Ligan yg dapat membentuk 2 ikatan dengan 2 atom logam

t i h d k di b t k j b t Mi l OH Cl Fterpisah dan kemudian membentuk jembatan. Misalnya OH-, Cl-, F-, NH2-, O2-, CO, SO42- dan O2-

Jenis logamBerdasarkan konfigurasinya:- Ion dengan konfigurasi sama dengan konfigurasi gas mulia

ion ini dpt membentuk ikatan mulai dari bersifat ionik sampai kovalen sesuai dengan kenaikanmuatan ionnyamuatan ionnya

- Ion dengan 18 elektronion dg konfigurasi ns2 np6 nd10 juga simetri scr spherical termasuk logam-logam transisi dankeadaan oksida negatifkeadaan oksida negatif

- Ion pasangan inert (ns2)- Ion logam transisi (ndx, x = 1-9)

Nomenclature of Coordination C d IUPAC R lCompounds: IUPAC Rules

The cation is named before the anionThe cation is named before the anion When naming a complex:

Li d d fi t Ligands are named first alphabetical order

Metal atom/ion is named last Metal atom/ion is named last oxidation state given in Roman numerals follows in

parenthesesparentheses Use no spaces in complex name

Nomenclature: IUPAC RulesNomenclature: IUPAC Rules

The names of anionic ligands end with theThe names of anionic ligands end with the suffix -o

ide suffix changed to o -ide suffix changed to -o -ite suffix changed to -ito

ate suffix changed to ato -ate suffix changed to -ato

Nomenclature: IUPAC RulesNomenclature: IUPAC RulesLigand Name

bromide, Br- bromo

chloride, Cl- chloro

cyanide, CN- cyano

hydroxide, OH- hydroxo

oxide, O2- oxo

fluoride, F- fluoro

Nomenclature: IUPAC RulesNomenclature: IUPAC RulesLigand Name

carbonate, CO32- carbonato

oxalate, C2O42- oxalato

sulfate, SO42- sulfato

thiocyanate, SCN- thiocyanato

thiosulfate, S2O32- thiosulfato

Sulfite, SO32- sulfito


Neutral ligands are referred to by the usualNeutral ligands are referred to by the usual name for the molecule

Example Example ethylenediamine

Exceptions Exceptions water, H2O = aqua ammonia, NH3 = amminea o a, 3 a e carbon monoxide, CO = carbonyl

Nomenclature: IUPAC Rules Greek prefixes are used to indicate the number

of each type of ligand when more than one is y gpresent in the complex di-, 2; tri-, 3; tetra-, 4; penta-, 5; hexa-, 6

If the ligand name already contains a Greek prefix, use alternate prefixes: bis-, 2; tris-, 3; tetrakis-,4; pentakis-, 5; hexakis-, 6 The name of the ligand is placed in parentheses


If a complex is an anion its name endsIf a complex is an anion, its name ends with the -ate

appended to name of the metal appended to name of the metalExample [Co(NO ) ]3- ; heksanitritokobaltat(III)[Co(NO2)6]3- ; heksanitritokobaltat(III)

Nomenclature: IUPAC RulesTransition

MetalName if in Cationic

ComplexName if in Anionic

ComplexSc Scandium ScandateSc Scandium ScandateTi titanium titanateV vanadium vanadateCr chromium chromateMn manganese manganateFe iron ferrateCo cobalt cobaltateNi i k l i k l tNi nickel nickelateCu Copper cuprateZn Zinc zincateZn Zinc zincate

IsomerismIsomerism

IsomersIsomers compounds that have the same composition

but a different arrangement of atomsbut a different arrangement of atoms Major Types

structural isomers structural isomers stereoisomers

Structural IsomersStructural Isomers

Structural IsomersStructural Isomers isomers that have different bonds


Coordination-sphere isomersCoordination sphere isomers differ in a ligand bonded to the metal in the

complex as opposed to being outside thecomplex, as opposed to being outside the coordination-sphere

Coordination-Sphere IsomersCoordination Sphere Isomers

ExampleExample[Co(NH3)5Cl]Br vs. [Co(NH3)5Br]Cl



C id i i ti i t Consider ionization in water[Co(NH3)5Cl]Br [Co(NH3)5Cl]+ + Br-

[Co(NH ) Br]Cl [Co(NH ) Br]+ + Cl-[Co(NH3)5Br]Cl [Co(NH3)5Br] + Cl



C id i it ti Consider precipitation

[Co(NH ) Cl]Br(aq) + AgNO (aq) [Co(NH ) Cl]NO (aq) + AgBr(aq)[Co(NH3)5Cl]Br(aq) + AgNO3(aq) [Co(NH3)5Cl]NO3(aq) + AgBr(aq)

[Co(NH3)5Br]Cl(aq) + AgNO3(aq) [Co(NH3)5Br]NO3(aq) + AgCl(s)


Linkage isomersLinkage isomers differ in the atom of a ligand bonded to the

metal in the complexmetal in the complex

Linkage IsomersLinkage Isomers

ExampleExample [Co(NH3)5(ONO)]2+ vs. [Co(NH3)5(NO2)]2+

Linkage IsomersLinkage Isomersgg

Linkage IsomersLinkage Isomers

ExampleExample [Co(NH3)5(SCN)]2+ vs. [Co(NH3)5(NCS)]2+

Co-SCN vs. Co-NCS

StereoisomersStereoisomers

StereoisomersStereoisomers Isomers that have the same bonds, but

different spatial arrangementsdifferent spatial arrangements


Geometric isomersGeometric isomers Differ in the spatial arrangements of the

ligandsligands

Geometric Isomers

cis isomer trans isomerPt(NH ) ClPt(NH3)2Cl2

Geometric Isomers

cis isomer trans isomer[Co(H O) Cl ]+[Co(H2O)4Cl2]


Geometric isomersGeometric isomers Differ in the spatial arrangements of the

ligandsligands Have different chemical/physical properties

different colors melting points polaritiesdifferent colors, melting points, polarities, solubilities, reactivities, etc.


Optical isomersOptical isomers isomers that are nonsuperimposable mirror

imagesimages said to be chiral (handed) referred to as enantiomers

A substance is chiral if it does not have a plane of symmetry

Example 1

mirroor plane

cis-[Co(en)2Cl2]+

i i 180Example 1

rotate mirror image 180

180 180

nonsuperimposableExample 1

cis-[Co(en)2Cl2]+

enantiomersExample 1

cis-[Co(en)2Cl2]+

Example 2

mirrror planne

trans [Co(en) Cl ]+trans-[Co(en)2Cl2]+

Example 2i i 180rotate mirror image 180

180


Example 2Superimposable not enantiomersSuperimposable-not enantiomers


Properties of Optical IsomersProperties of Optical Isomers

EnantiomersEnantiomers possess many identical properties

solubility melting point boiling point color solubility, melting point, boiling point, color, chemical reactivity (with nonchiral reagents)

different in: interactions with plane polarized light

Optical IsomersOptical Isomers

polarizing filter plane

l i d li hpolarized light

light source

unpolarized light

(random vibrations)(vibrates in one plane)


optically active sample in solution

polarizing filter plane polarized

light in solutionlight

rotated polarizedrotated polarized light


optically active sample in solution

polarizing filter plane polarized

light in solutionlight

Dextrorotatory (d) = right rotation

rotated polarized

Levorotatory (l) = left rotation

Racemic mixture = equal rotated polarized

lightamounts of two enantiomers; no net rotation

Properties of Optical Isomers Enantiomers

possess many identical propertiesp y p p solubility, melting point, boiling point, color, chemical

reactivity (with nonchiral reagents) different in:

interactions with plane polarized lightti it ith hi l t reactivity with chiral reagents

Example

d-C4H4O62-(aq) + d,l-[Co(en)3]Cl3(aq)d C4H4O6 (aq) d,l [Co(en)3]Cl3(aq) d-[Co(en)3](d-C4H4O62- )Cl(s) + l-[Co(en)3]Cl3(aq) +2Cl-

(aq)

Properties of transition metal complexes:Properties of transition metal complexes: usually have color

dependent upon ligand(s) and metal iondependent upon ligand(s) and metal ion many are paramagnetic

due to unpaired d electronsp degree of paramagnetism dependent on ligand(s)

[Fe(CN)6]3- has 1 unpaired d electron[F F ]3 h 5 i d d l t [FeF6]3- has 5 unpaired d electrons

Wk2Coord Chem- Intro

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