Mono- and dinuclear non-heme iron-nitrosyl complexes: Models for key intermediates in bacterial nitric oxide reductases

摘要

High-spin non-heme iron-nitrosyls are of direct interest to both the chemical and biological communities as these species exhibit interesting chemical properties and act as direct models for enzymatic intermediates. The electronic ground state of the ferrous NO complexes, {Fe-NO}~7, is best described as high-spin Fe~Ⅲ antiferromagnetically coupled to NO", generating the spectroscopically observed S = 3/2 ground state. These species have been identified as catalytically relevant to a variety of NO-reducing enzymes such as bacterial nitric oxide reductase (NorBC) and flavo(rubredoxin) nitric oxide reductase (FNOR). Recently, the corresponding one-electron reduced {Fe-NO}8 (nitroxyl) complexes have also been implicated as biologically significant species. In this review the available spectroscopic data for {Fe-NO}~7 and {Fe-NO}~8 mono- and dinuclear non-heme iron-nitrosyls are summarized, and the implications of these results with respect to the electronic structures and reactivities of these species, in particular towards NO reduction, are discussed.