Molecular Electrochemical Reductive Splitting of Dinitrogen with a Molybdenum Complex

Nitrogen reduction under mild conditions (room T and atmospheric P), using a non‐fossil source of hydrogen remains a challenge. Molecular metal complexes, notably Mo based, have recently been shown to be active for such nitrogen fixation. We report electrochemical N(2) splitting with a Mo(III) triphosphino complex [(PPP)MoI(3)], at room temperature and a moderately negative potential. A Mo(IV) nitride species was generated, which is confirmed by electrochemistry and NMR studies. The reaction goes through two successive one electron reductions of the starting Mo species, coordination of a N(2) molecule, and further splitting to a Mo(IV) nitride complex. Preliminary DFT studies support the formation of a bridging Mo(I)N(2)Mo(I) dinitrogen dimer evolving to the Mo nitride via a low energy transition state. This example joins a short list of molecular complexes for N(2) electrochemical reductive cleavage. It opens a door to electrochemical proton‐coupled electron transfer (PCET) conversion studies of N(2) to NH(3).