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Transition metals 1, CAR
[edit]"Coordination Chemistry of the Transition Metals, Part 1"
Structure and bonding in transition metal complexes
[edit]- Revision of crystal field theory, which does not explain the spectrochemical series
- Ligand field theory (application of molecular orbital theory to bonding in complexes)
- eg* orbitals are antibonding, so when occupied, metal-ligand bonds weaken and lengthen (and substitution rxns happen faster)
- Stronger metal-ligand interaction raises eg* (and lowers eg), while t2g is unaffected → greater Δo
- Pi bonding: by symmetry, t2g can and eg and eg* cannot do π bonding, π backbonding
- π donor ligands – Δo ↓ (weak field ligands)
- π acceptor ligands – Δo ↑ (strong field ligands)
- good σ donors – Δo ↑
- poor σ donors – Δo ↓
- Metal ligand multiple bonds, such as imido ligands
- Structural consequences of particular d electron counts
- Jahn-Teller effect: J-T theorem
- "any non-linear molecule in a degenerate electronic ground state will undergo a geometrical distortion that removes that degeneracy"
- for symmetry reasons, tend to get elongation of bonds along z-axis and shortening of bonds in xy plane, so in Cu2+, d9, get (dz2)2(dx2−y2)1
- Planar-octahedral and planar-tetrahedral equilibria in d8 complexes
- Lifschitz salts: [Ni(L-L)2]X2 vs. [Ni(L-L)2X2]
- [NiBr2PEtPh2] brown, square planar, diamagnetic vs. green, tetrahedral, paramagnetic: Acta Cryst. (1992). C48, 406-408
- Jahn-Teller effect: J-T theorem
- Stability constants of complexes
Thermodynamic stability in transition metal complexes
[edit]- Chelate effect
- Macrocyclic effect
- Template reaction
- HSAB theory
- Effects of CFSE
- Irving-Williams series
- Redox in transition metal complexes: Co(II)-Co(III) and Cu(I)-Cu(II)