Electronic Structure of Metal Ion-Dioxygen Complexes

Author: Miskowski, Vincent Mark

Year: 1973

Degree: Dissertation (Ph.D.)

Advisor: Gray, Harry B.

Committee Member: Unknown, Unknown

Option: Chemistry

DOI: 10.7907/ZFYP-9D77

Abstract

The electronic structures of cobalt complexes containing O2 units as ligands have been investigated, primarily by electronic spectroscopy. Various cobalt complexes containing, the structural units present in the O2 complexes were investigated, and a systematic and self-consistent classification of their ligand field electronic transitions, charge-transfer electronic transitions, and excited state reactivities developed, which provided a basis for understanding the O2 complexes.

The O2 complexes investigated were all found to contain low-spin d6 cobalt (III) central metal ions, by spectroscopic criteria, and either peroxide or superoxide ligands. The O2n- ligands have positions in the spectrochemical series between those of ammonia and water, and have characteristic charge-transfer transitions in their complexes, superoxide complexes showing low energy metal-to-ligand transitions, while both superoxide and peroxide complexes show characteristic ligand-to-metal transitions in the UV. Extensive comparisons were made to O2 complexes of other metal ions, and the binding of dioxygen to metal ions concluded to be oxidative addition in general. Autoxidation of metal ions and the structures and properties of oxymetalloproteins have been considered in the light of these results, and the formulation of addition of O2 to Cu(I) and Fe(II) as one- and two-electron oxidative addition, respectively, is discussed.

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