Molecular Electrochemical Reductive Splitting of Dinitrogen with a Molybdenum Complex

Nitrogen reduction in mild conditions (i.e. room temperature and atmospheric pressure) and using a non-fossil source of hydrogen remains a high chemistry challenge. Molecular metal complexes, notably Mo based, have recently shown to be active for such nitrogen fixation. In this work, we report about the electrochemical N2 splitting with MoIII triphosphino com-plex ((PPP)MoI3), at room temperature and a moderately negative potential. A MoIV nitride species was generated, which was confirmed by electrochemistry and NMR studies. The reaction goes through the bi-electronic reduction of the starting Mo species, coordination of an N2 molecule, and further splitting to a MoIV nitride complex. Preliminary DFT investigation supports the intermediacy of a bridging MoIN2MoI dinitrogen dimer evolving to the Mo nitride via a low energy transition state. This example joins a short list of molecular electrochemical complexes for N2 reductive cleavage. It opens a door to molecular electrochemical PCET conversion studies of N2 to NH3.