Coordination Chemistry

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Coordination Chemistry

• ligands bonding to metals

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Donor-Acceptor Complexes
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Definitions
Lewis Acid acceptor usually a transition
metal cation Lewis Base donor ligand
usually something with a lone electron
pair Coordination number of metal-ligand
attachments Denticity of attachments a
ligand makes
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Common Ligands
Monodentate Ligands Halides F-, Cl-, Br-,
I- O2-, S2-, OH-, CN- NH3, H2O, CO
Bidentate Ligands
Polydentate Ligands heme, salen
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Monodentate complexes
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Monodentate complexes
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Bidentate ligand complexes
Co(en)2Cl2
Ni(DMG)2
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Bidentate complexes
Co(en)32
Fe(phen)32
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Polydentate complexes
Co(salen)
chlorophyll
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Fe-heme
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Polydentate complexes
Fe-heme
O2-Fe-heme
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Determining Metal Oxidation States
Ag(NH3)2NO3 K2NiCl4 Co(en)2Cl2Cl Cr(H
2O)4CO3Br
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Isomerization in Coordination Compounds

• Do for octahedral Complexes

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Inner and Outer Spheres
Co(NH3)4Cl2Cl? H2O
Co(NH3)4(H2O)ClCl2
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All compounds
Structural (constitutional)
Stereo
linkage ionization hydration
geometric optical
Co(NH3)5ClNO2 Co(NH3)5NO2Cl
Co(NH3)4Cl(H2O)Cl2 Co(NH3)4Cl2Cl?H2O
Co(NH3)5SCN2 Co(NH3)5NCS2
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Linkage Isomers
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Ionization Isomers
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Hydration Isomers
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Optical Isomers enantiomers (mirror
images) key to recognizing no mirror planes of
symmetry Type 1. arrangement of monodentate
ligands Type 2. arrangement of bidentate
ligands
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Geometric isomerism like cis-trans
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Geometric isomerism
Fac- isomer
Mer- isomer
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Geometric Isomers predicting numbers Use
shorthand M metal a, b, c, etc. are
different ligands Example 1 Co(NH3)4Cl2
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Example 2 Co(NH3)3BrCl2
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Example 3 Co(NH3)3enBr2