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Nov. 2006 Shanghai Jiao Tong University

Chemistry of Coordination Chemistry of Coordination CompoundsCompounds

Chapter 24

Nov. 2006 Shanghai Jiao Tong University

The Position of the Transition Elements on The Position of the Transition Elements on the Periodic Tablethe Periodic Table

Ca

Sr

Ba

Ra

s1

s2

d3 d10d4 d5

d10s1

d10s2

s2p1·············s2p6

ds

sd

Nov. 2006 Shanghai Jiao Tong University

Electron Configurations and other properties of the first row transition Metals

Oxidation States of the 1st Row Transition Metals(most stable oxidation numbers are shown in red)

Nov. 2006 Shanghai Jiao Tong University

3d3 3d4 3d5 3d6 3d7 3d8 3d9 3 d10 3d104s1

+2

Ca

-1

Os+8

Zn

+2

d0+4

Scandium Titanium Vanadium

Chromium Manganese Iron

Nov. 2006 Shanghai Jiao Tong University Cobalt Nickel Copper 22.2

cation

coor

Metal at

dinate compou moleculesligan

omcomplex io

tsions

a A

a counter ion

dn

n

⎧⎨⎩⎧

⎧ ⎧⎪⎪⎨⎪

⎪⎪⎪

⎪⎨

⎨⎩⎩

⎪⎪⎪⎩

Coordination CompoundsCoordination Compounds

[Cr(H2O)4Cl2] Cl

[Co(NH3)4Cl2] SO4

K4 [Fe(NCS)6]

The molecules or ions that surround the metal in a complex ion are called ligands.

Nov. 2006 Shanghai Jiao Tong University

Nov. 2006 Shanghai Jiao Tong University

Coordination CompoundsCoordination Compounds

A ligand has at least one unshared pair of valence electrons

• •

H

N

HHH

O

H

• • ••

• •••Cl• •

••

- ••C O••

The atom in a ligand that is bound directly to the metal atom is the donor atomdonor atom.

Ligands with:one donor atom monodentate H2O, NH3, Cl-

two donor atoms bidentate ethylenediamine

three or more donor atoms polydentate EDTA

Nov. 2006 Shanghai Jiao Tong University

Coordination CompoundsCoordination Compounds

H2N CH2 CH2 NH2• • • •

bidentate ligand

Nov. 2006 Shanghai Jiao Tong University

Coordination CompoundsCoordination Compounds

polydentate ligand(EDTA)

CH2 CH2 NN

H2C

H2CCH2

CH2

COOH

COOH

HOOC

HOOC

Bidentate and polydentate ligands are called chelating agents

Nov. 2006 Shanghai Jiao Tong University

Nov. 2006 Shanghai Jiao Tong University

Naming Coordination Compounds

• The cation is named before the anion.

• Within a complex ion, the ligands are named first in alphabetical order and the metal atom (or ion) is named last.

• The names of anionic ligands end with the letter o. Neutral ligands are usually called by the name of the molecule.(The exceptions are H2O (aquo), CO (carbonyl), and NH3(ammine)).

Nov. 2006 Shanghai Jiao Tong University

Naming Coordination Compounds

• When several ligands of a particular kind are present, the Greek prefixes di-, tri-, tetra-, penta-, and hexa- are used to indicate the number. If the ligand contains a Greek prefix, use the prefixes bis, tris, and tetrakis to indicate the number.

• The oxidation number of the metal is written in Roman numerals following the name of the metal.

• If the complex is an anion, its name ends in –ate.

Nov. 2006 Shanghai Jiao Tong University

Nov. 2006 Shanghai Jiao Tong University

Naming Coordination Compounds

4 6cation anion

K [Fe(CN) ] Potassium hexacyanoferrate(II)cation anion

3 6 3[Co(NH ) ]Clcation anion

Hexaamminecobalt(III) chlorideanioncation

- Fe anion6 oxidationCN number

hexa cyano ferrate (II) ion4-3 6[Fe(NH ) ]

anion

6 Coligand name oxidation number

tris (ethylenediamine) cobalt (III) chloride3 3[Co(en) ]Clcation anion

Nov. 2006 Shanghai Jiao Tong University

Naming Coordination CompoundsEnglish Name Anion NameCopper CuprateGold AurateIron FerrateLead PlumbateSilver ArgentateTin Stannate

Write the structural formula corresponding to each of the following IUPAC names:

a. hexaaquairon(II) chloride; b. tetraamminedichloroplatinum chloridec. Potassium hexachloroplatinate(IV)

Nov. 2006 Shanghai Jiao Tong University

Structure of Coordination CompoundsStructure of Coordination Compounds

lewis blew aseis aci

2+ - 4-

d6Fe + CN [Fe(CN) ]⎯⎯→

Three important properties of complexes: Three important properties of complexes: a.a. IsomerismIsomerismb.b. ColorColorc.c. ParamegnetismParamegnetism

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination Compounds

Constitutional isomerismIsomerism

Steroisomerism⎧⎨⎩

Constitutional isomerismConstitutional isomerism: : are isomers that differ in how the atoms are joined together.

StereoisomerismStereoisomerism: : are isomers in which the atoms are bonded to each other in the same order, but differ in the precise arrangement of the atoms in the space.

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination Compounds

Constitutional isomerismConstitutional isomerism::

4 43 5 3 5[Co(NH ) ] and [Co(NHBr BrO ) ]S SO

3 4 4 3 4 4[ (NH ) ][ Cl ] andP [ (NH )Cu Cu][Pt Clt ]

doner doner ato

3 4 2 3 4 2

m ato

2

m

[Co(NH ) ( NO)]Cl and [Co(NH ) N( O )]ClO

Nov. 2006 Shanghai Jiao Tong University

Constitutional isomerismConstitutional isomerism::

doner atom

done

3 5 2 2

3 5 2r

atom

[Co(NH ) ( O )]Cl

[Co(NH ) ( NO O)]Cl

N

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination CompoundsConstitutional isomerism

IsomerismSteroisomeris

Geometric isomerismOptical isomer

mism

⎧⎪

⎧⎨⎨⎪⎩⎩

Geometric isomersGeometric isomers: : are isomers in which the atoms are bonded to each other in the same way, but differ because some atoms occupy different relative position in space.

cis-[Pt(NH3)2Cl2] trans-[Pt(NH3)2Cl2]

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination Compounds

cis

trans

trans-[Co(NH3)4Cl2]cis-[Co(NH3)4Cl2]

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination CompoundsConstitutional isomerism

IsomerismSteroisomeris

Geometric isomerismOptical isomer

mism

⎧⎪

⎧⎨⎨⎪⎩⎩

Optical isomers (enantiomers)Optical isomers (enantiomers): : are isomers that are non-superimposable mirror images of one another.

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination CompoundsConstitutional isomerism

IsomerismSteroisomeris

Geometric isomerismOptical isomer

mism

⎧⎪

⎧⎨⎨⎪⎩⎩

Isomers of Co(en)33+

Nov. 2006 Shanghai Jiao Tong University

Isomerism of Coordination CompoundsIsomerism of Coordination Compounds

trans-[Co(en)2Cl2]cis-[Co(en)2Cl2]

optical isomers not optical isomers

achiralachiralchiralchiral

Nov. 2006 Shanghai Jiao Tong University

The Optical Isomers of Co(en)2CI2+

Nov. 2006 Shanghai Jiao Tong University

The Optical Isomers of Co(en)2CI2+

Nov. 2006 Shanghai Jiao Tong University

Un-polarized Light Consists of Waves Vibrating in Many Different Planes

Nov. 2006 Shanghai Jiao Tong University

Color of Coordination CompoundsColor of Coordination Compounds

The color of the different coordination compounds of CoThe color of the different coordination compounds of Co3+3+

3 2 3 23 6 3 5 3 5 2 3 5 3 4 2[Co(NH ) ] ,[Co(NH ) ] ,[Co(NH ) ] ,[Co(NH ) ] , [Co(NH ) ]NCS H O Cl trans Cl+ + + + +−

Nov. 2006 Shanghai Jiao Tong University

Color of Coordination CompoundsColor of Coordination Compounds

510

(green and yellow)absorption nmλ =

The absorption spectrum of [Ti(H2O)6]3+ at 510 nm (green and yellow), the complex transmits all light except green and yellow. The complex is purple

Nov. 2006 Shanghai Jiao Tong University

Magnetism of Coordination compoundsMagnetism of Coordination compounds

• Many transition metal complexes are paramagneticparamagnetic (have unpaired electrons)

• An interesting observations ( a dd66 metal ion):– [Co(NH3)6]3+ has no unpaired electrons, – [CoF6]3- has four unpaired electrons.

• A bonding theory to account for both color and magnetism in transition metal complexes.

???

Nov. 2006 Shanghai Jiao Tong University

Crystal-Field Theory

provide

donor

Metal ionLigands

empty orbitalselectrons pa ir s

⎯⎯⎯→

⎯⎯⎯→

Nov. 2006 Shanghai Jiao Tong University

Structure of Coordination CompoundsStructure of Coordination Compounds

The Ligand Arrangements for Coordination Numbers 2, 4, and 6

Nov. 2006 Shanghai Jiao Tong University

The Hybrid Orbitals Requiredfor OctahedralOctahedral and LinearLinear Complex Ions

Octahedral ligand arrangement for Co3+

Nov. 2006 Shanghai Jiao Tong University

The Hybrid Orbitals Requiredfor TetrahedralTetrahedral and Square planerSquare planer

Complex Ions

Nov. 2006 Shanghai Jiao Tong University

An Octahedral Arrangement of Point-Charge Ligands and the Orientation of the 3d Orbitals

Nov. 2006 Shanghai Jiao Tong University

Bonding in Coordination CompoundsBonding in Coordination Compounds

Isolatedtransition metal

atomBonded

transition metalatom

Crystal field Splitting of

outer d orbital in octahedral field

Crystal field splitting ( ∆): the energy difference between two sets of d orbitals in a metal atom when ligands are present

Nov. 2006 Shanghai Jiao Tong University

Bonding in Coordination Compounds

Ti3+: a d1 ion

∆ = hν

The absorbance spectrum of Ti(H2O)63+, the maximum

absorption peak at 498nm

Nov. 2006 Shanghai Jiao Tong University

Bonding in Coordination Compounds

Spectrochemical SeriesI- < Br- < Cl- < OH- < F- < H2O < NH3 < en < CN- < CO

Weak field ligandsSmall Small ∆∆

Strong field ligandsLarge Large ∆∆

Nov. 2006 Shanghai Jiao Tong University

CrystalCrystal--Field TheoryField Theory

I- < Br- < Cl- < OH- < F- < H2O < NH3 < en < CN- < CO

Nov. 2006 Shanghai Jiao Tong University

CrystalCrystal--Field TheoryField Theory

Nov. 2006 Shanghai Jiao Tong University

Bonding in Coordination Compounds

High-spin High-spinLow-spin Low-spin

Orbital Diagrams for high-spin and low-spin octahedral complex

Nov. 2006 Shanghai Jiao Tong University

CrystalCrystal--Field TheoryField Theory

Nov. 2006 Shanghai Jiao Tong University

Bonding in Coordination Compounds

Nov. 2006 Shanghai Jiao Tong University

Crystal field splitting between d orbitals in Crystal field splitting between d orbitals in a tetrahedral complexa tetrahedral complex

Nov. 2006 Shanghai Jiao Tong University

Crystal field splitting between d orbitals in Crystal field splitting between d orbitals in a a tetrahedraltetrahedral complexcomplex

Nov. 2006 Shanghai Jiao Tong University

The Crystal Field Diagrams for Octahedral Octahedral and TetrahedralTetrahedral

Complexes

Nov. 2006 Shanghai Jiao Tong University

The d Energy Diagrams for SquareSquare--Planar Planar and LinearLinear

Complexes

Nov. 2006 Shanghai Jiao Tong University

Chemistry In Action: Coordination Compounds in Living Systems

The Heme Complex

Nov. 2006 Shanghai Jiao Tong University

Nov. 2006 Shanghai Jiao Tong University

Chemistry In Action: Cisplatin – The Anticancer Drug

Nov. 2006 Shanghai Jiao Tong University

Chlorophyll

Nov. 2006 Shanghai Jiao Tong University

HomeworkChapter 24:24.02 a to f and K[MnO4]**24.04 a to f and [Cr(C6H6)2]**24.06 a, e and tetraammincopper(II)sulfate24.08 a, b and d24.10 a and b24.12**24.14 a and c** optional, for extra credits 24.18, 24.28, 24.30, 24.46

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