Metal-Sulfur Compounds in N2 Reduction and Nitrogenase-Related Chemistry.

Transition metal-sulfur (M-S) compounds are an indispensable means for biological systems to convert N2 into NH3 (biological N2 fixation), and these may have emerged by chemical evolution from a prebiotic N2 fixation system. With a main focus on synthetic species, this article provides a comprehensive review of the chemistry of M-S compounds related to the conversion of N2 and the structures/functions of the nitrogenase cofactors. Three classes of M-S compounds are highlighted here: multinuclear M-S clusters structurally or functionally relevant to the nitrogenase cofactors, mono- and dinuclear transition metal complexes supported by sulfur-containing ligands in N2 and N2Hx (x = 2, 4) chemistry, and metal sulfide-based solid materials employed in the reduction of N2. Fair assessments on these classes of compounds revealed that our understanding is still limited in N2 reduction and related substrate reductions. Our aims of this review are to compile a collection of studies performed at atomic to mesoscopic scales and to present potential opportunities for elucidating the roles of metal and sulfur atoms in the biological N2 fixation that might be helpful for the development of functional materials.