Metal - Oxygen Bonds, and Co-ordination Complexes with Tetragonal Pyramidal Configurations

Abstract

OUR studies of certain compounds which the hæmoproteins form with peroxides and other strong oxidizing agents suggest that in these the iron is quadrivalent¹. In the case of the most fully investigated compound, obtained by oxidizing ferrimyoglobin, the evidence indicates that an oxygen atom is bonded to the iron². Such a compound would be a co-ordination complex of the hypothetical ferryl ion FeO²⁺, and, since the iron – ligand bonds are covalent as judged from magnetic susceptibility studies³, it could be envisaged as a familiar d²sp³ covalent octahedral complex with four Fe—N bonds in the plane of the porphyrin ring and two bonds at right angles, one between the Fe and the protein and the other between the Fe and the oxygen. Other complexes where similarly bonded oxygen atoms are well authenticated, and particularly complexes more closely related in gross chemical structure than obvious examples like the ferrate and manganate ions, are the uranium and osmium compounds, UO₂ (N–base)₂ X₂, OsO (NH₃)₄ X₂, and the complexes of quadrivalent vanadium.