Recent advances in catalytic nitrogen fixation using transition metal–dinitrogen complexes under mild reaction conditions

Abstract

Recent advances in catalytic nitrogen fixation using well-defined molecular transition metal–dinitrogen complexes and their precursors as catalysts under ambient or mild reaction conditions are summarized in terms of varieties of transition metals, ligands, reductants and proton sources, and catalytic reaction pathways. Several transition metal complexes have been applied as catalysts for nitrogen fixation, while Mo catalytic systems successfully fix nitrogen under ambient conditions. H2O becomes available as a proton source for the formation of NH3 via proton-coupled electron transfer processes, and turnover frequencies for the formation of NH3 are now relevant to the biological nitrogen fixation, making gram-scale preparation of NH3 possible. Pioneering electrochemical nitrogen fixation systems mediated by molecular catalysts have been also under development. Targets and strategies for future research plans for improving catalytic systems are further discussed.