Molecular orbital theory for octahedral and tetrahedral metal complexes

Self-consistent charge and configuration (SCCC) molecular orbital calculations are reported for 32 selected octahedral and tetrahedral first-row transition-metal complexes containing halide and chalcogenide ligands. It is found that for the range of metal oxidation states II through IV, Fσ, chosen to fit the experimental Δ, is a function of only the metal atomic number for constant Fπ. In the range of formal metal oxidation numbers V through VII, Fσ, is also a function of oxidation number. Calculated and observed trends in covalency, Δ values, and first L→M charge-transfer energies are compared. The conclusion is drawn that the molecular orbital method, in its present formulation, gives a reasonable account of the ground states and low excited states in simple metal complexes.