On the relation between oxidation states and d-electron populations of the 1st row transition metal complexes I. Tetrachloro complexes

The structures of [MCl4](q) complexes, q = 0, -1 and -2, of the 1st row transition metals in various spin states were optimized at MP2/6-311G* level of theory. Their electron structure was evaluated by the Mulliken population analysis and alternatively by the Natural population analysis at MP2 and DFT levels of theory using 15 functionals. For constant charge q of the complex the changes of the physical oxidation states based on [Ar]d(n) occupations and of the calculated d-electron population d(x) at the central atom are equal. Their increase with the negative charge q of the complex can be concluded as well. The transition metal complexes with 'innocent' ligands can be used for scaling the analogous complexes with 'non-innocent' ligands by estimating their physical oxidation states. (C) 2021 Elsevier Ltd. All rights reserved.

Automated summary

In this study, the structures and electron structures of a series of [MCl4](q) complexes of first-row transition metals were optimized, showing that the physical oxidation states and calculated d-electron populations increase with the negative charge q. Additionally, transition metal complexes with 'innocent' ligands can be used to estimate the physical oxidation states of analogous complexes with 'non-innocent' ligands.