Executive Summary : | Nitrogenases are essential enzymes that perform the reduction of N2 to ammonia, with iron-sulfur clusters catalyzing multielectron reductions of small molecules. The mechanism of substrate reduction by nitrogenases is unknown, but recent spectroscopic work suggests that it involves binding N2 to iron and iron-hydride species. Synthetic compounds with these features are needed to evaluate the feasibility of proposed functional groups on iron-sulfur clusters, establish the spectroscopic signatures of these functional groups, and learn whether their reactivity is consistent with the enzymatic products. Oxygen metabolism is a vital process in animal biological systems, and the most important metals involved in biological oxidations are iron and copper. The long-term goal is to learn the mechanism of reduction of nitrogenase substrates using the synthetic analogue approach, which is structurally well-defined and can perform elementary transformations under simpler conditions than those in the protein environment. The project aims to synthesize and study iron-sulfur clusters with unsaturated iron, create high-spin molecules containing hydrides, create complexes of dinitrogen with high-spin iron, and create complexes of oxygen with high spin iron and copper. |