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Nov. 2006 Shanghai Jiao Tong University
Chemistry of Coordination Chemistry of Coordination CompoundsCompounds
Chapter 24
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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
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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)
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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.
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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
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Coordination CompoundsCoordination Compounds
H2N CH2 CH2 NH2• • • •
bidentate ligand
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Coordination CompoundsCoordination Compounds
polydentate ligand(EDTA)
CH2 CH2 NN
H2C
H2CCH2
CH2
COOH
COOH
HOOC
HOOC
Bidentate and polydentate ligands are called chelating agents
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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)).
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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.
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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
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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)
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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
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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.
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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
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Constitutional isomerismConstitutional isomerism::
doner atom
done
3 5 2 2
3 5 2r
atom
[Co(NH ) ( O )]Cl
[Co(NH ) ( NO O)]Cl
N
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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]
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Isomerism of Coordination CompoundsIsomerism of Coordination Compounds
cis
trans
trans-[Co(NH3)4Cl2]cis-[Co(NH3)4Cl2]
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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.
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Isomerism of Coordination CompoundsIsomerism of Coordination CompoundsConstitutional isomerism
IsomerismSteroisomeris
Geometric isomerismOptical isomer
mism
⎧⎪
⎧⎨⎨⎪⎩⎩
Isomers of Co(en)33+
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Isomerism of Coordination CompoundsIsomerism of Coordination Compounds
trans-[Co(en)2Cl2]cis-[Co(en)2Cl2]
optical isomers not optical isomers
achiralachiralchiralchiral
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The Optical Isomers of Co(en)2CI2+
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The Optical Isomers of Co(en)2CI2+
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Un-polarized Light Consists of Waves Vibrating in Many Different Planes
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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+ + + + +−
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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
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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.
???
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Crystal-Field Theory
provide
donor
Metal ionLigands
empty orbitalselectrons pa ir s
⎯⎯⎯→
⎯⎯⎯→
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Structure of Coordination CompoundsStructure of Coordination Compounds
The Ligand Arrangements for Coordination Numbers 2, 4, and 6
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The Hybrid Orbitals Requiredfor OctahedralOctahedral and LinearLinear Complex Ions
Octahedral ligand arrangement for Co3+
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The Hybrid Orbitals Requiredfor TetrahedralTetrahedral and Square planerSquare planer
Complex Ions
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An Octahedral Arrangement of Point-Charge Ligands and the Orientation of the 3d Orbitals
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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
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Bonding in Coordination Compounds
Ti3+: a d1 ion
∆ = hν
The absorbance spectrum of Ti(H2O)63+, the maximum
absorption peak at 498nm
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Bonding in Coordination Compounds
Spectrochemical SeriesI- < Br- < Cl- < OH- < F- < H2O < NH3 < en < CN- < CO
Weak field ligandsSmall Small ∆∆
Strong field ligandsLarge Large ∆∆
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CrystalCrystal--Field TheoryField Theory
I- < Br- < Cl- < OH- < F- < H2O < NH3 < en < CN- < CO
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CrystalCrystal--Field TheoryField Theory
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Bonding in Coordination Compounds
High-spin High-spinLow-spin Low-spin
Orbital Diagrams for high-spin and low-spin octahedral complex
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CrystalCrystal--Field TheoryField Theory
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Bonding in Coordination Compounds
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Crystal field splitting between d orbitals in Crystal field splitting between d orbitals in a tetrahedral complexa tetrahedral complex
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Crystal field splitting between d orbitals in Crystal field splitting between d orbitals in a a tetrahedraltetrahedral complexcomplex
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The Crystal Field Diagrams for Octahedral Octahedral and TetrahedralTetrahedral
Complexes
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The d Energy Diagrams for SquareSquare--Planar Planar and LinearLinear
Complexes
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Chemistry In Action: Coordination Compounds in Living Systems
The Heme Complex
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Chemistry In Action: Cisplatin – The Anticancer Drug
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Chlorophyll
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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