REDUCTION OF NITRATE BY MONOMERIC MOLYBDENUM(V) COMPLEXES IN DIMETHYLFORMAMIDE

As a model system for the molybdenum enzyme nitrate reductase, the reduction of NO3- by monomeric Mo(V) complexes of the formulas MoOCl3L (L=α,α'-bipyridyl, o-phenanthroline), MoOClL2 (L=8-hydroxyquinoline, 8-mercaptoquinoline), MoOC1(CH3OH)L (L=o-(salicylidenimino)phenol), and MoOCIL (L=o-bis(salicylidenimino)benzene) has been investigated. The complexes, with the exception of MoOCIL, reduce NO3- in a one-electron step with complex kinetics, producing NO2 and the corresponding Mo(VI) compound. A general mechanism is proposed involving preliminary dissociation of a Cl-, followed by intermediate formation of a molybdenum(V)-nitrate complex coordinated cis to the oxo group, which subsequently undergoes transfer of an oxo group. Possible applications to enzymatic nitrate reduction are discussed. © 1979, American Chemical Society. All rights reserved.