Transition Metal Complexes- Structure

Coordination Sphere

Outer-sphere

Inner-sphere

What Is A Coordination Compound?http://www.chem.purdue.edu/gchelp/cchem/

Low Coordination

Four Coordination

Common for:1st Row metal with

donor ligands

Four Coordination

Four Coordination

Common for:1st Row d8 with

acceptor ligands2nd & 3rd Row d8

Four Coordination

GeometricIsomerism

Five Coordination

Five Coordination

Five Coordination

Berry pseudorotation

Six Coordination

Oh

Six Coordination

D4h D4h

D2h D3d

Six Coordination

Seven Coordination

Eight and Higher Coordination

Polymetallic Complexes

Nomenclature Rules1. The ligands are named first; the prefixes di,

tri, tetra, and so on are used to indicate thenumber of each kind of ligand present.[Sometimes the prefixes bis (2 ligands), tris(3 ligands), and tetrakis (4 ligands) are alsoused, especially when the ligand name iscomplicated or already includes di, etc.]Negative ligands are given names which endin -o.

Nomenclature Rules

2. The ligand names are given in alphabeticalorder. Some ligands have familiar namesalso used in naming other types ofcompounds (eg. chloro, cyano); others havenames special to complexes (eg. carbonato,CO3

2-; aqua, H2O).

3. The name of the central metal atom or ionfollowed by its oxidation state in parenthesesis given after the ligand names (notseparated by a space).

Nomenclature Rules4. When a complex ion has a negative charge,

the name of the central metal atom is giventhe ending ate.For some of the elements, the ion name isbased on the Latin, for example, ferrate foriron, Fe; plumbate for lead, Pb. When namingonly the ion, the word "ion" is always used inthe name.In naming a co-ordination compound, thename of the cation is given first as usual,followed by the name of the anion.

Examples

K+[Pt(NH3)Cl5]-

potassium amminepentachloroplatinate(IV)

[Co(NH3)4SO4]+ NO3

-

tetraamminesulfatocobalt(III) nitrate

Examples

Re2Cl82-

Octachlorodirhenate(III)

(H3N)5CrOCr(NH3)54+

-oxo-bis[pentaamminechromium(III)]

Ligand NomenclatureLigand NameF- fluoroCl- chloroBr- bromoI- iodoCN- cyanoSCN- thiocyanatoNCS- isothiocyanatoNO2

- nitroONO- nitritoOH- hydroxo

Ligand NameO2

- oxoOSO3

2- sulfato (SO42-)

OSO22- sulfito (SO3

2-)CO3

2- carbonatoC2O4

2- oxalatoNH3 ammine (notice 2 m’s)H2O aquaCO carbonylNO nitrosylPR3 trialkyl- or triarylphosphine

SCN- - ambidentate ligand

Polydentate Ligands and Chelate

Some Bidentate Ligands

Ethylenediammine (en) Acetylacetonate ion (acac)

Phenanthroline (phen) Oxalate ion (ox)

Polydentate Ligands and Chelate

Polydentate ligand–ligand with more than onesite to connect to a metal center

Monodentate, bidentate, tridentate,……Chelate–polydentate ligand/metal ring

Bite Angle

•Small bite angle may distort the geometryfrom ideal structure

IsomerismStructural isomers: contain the same number and

kinds of atoms, but one or more bonds is/are different(i.e., the connectivity between atoms is different).There are two types of structural isomers:coordination isomers, and linkage isomers

Stereo isomers: contain the same number and kinds ofatoms, and the same number and kinds of bonds (i.e.,the connectivity between atoms is the same), but theatoms are arranged differently in space. There aretwo types of stereo isomers:geometric isomers, and optical isomers

Linkage Isomerism

[Fe]-SCN [Fe]-NCS

GeometricIsomerism

Geometric Isomerism

facial meridional

fac cis trans

Optical Isomerism

Chiral–enantiomer pair

achiral

Optical Isomerismright hand screwleft hand screw