The Synthesis and Metal Complexes of Sulfur-Containing Models for Nitrogenase Enzymes

Abstract

Recently there has been a great deal of interest in synthetically modelling the active site of the enzyme nitrogenase.1 Nitrogenase is a member of a class of metalloenzymes which bind molybdenum at their active sites. The molybdoenzymes are responsible for many important naturally occurring redox processes. In the case of nitrogenase the redox process is the reductive fixation of atmospheric dinitrogen, N2. In nitrogen fixation, N2 is first bound to the active site of nitrogenase and then through a series of unknown intermediates reduced to ammonia. The exact structure of the active site of nitrogenase is not known, but EXAFS data shows it to consist of a cluster of approximate composition MoFe(6–8)S(4–8). 2 The molybdenum atom is believed to be the site where N2 is bound, but the precise nature of the coordination is not known.1 It is hoped that a good synthetic model of the active site will show the mode of nitrogen binding.