Molecular Electrochemical Reductive Splitting of Dinitrogen with a Molybdenum Complex

摘要

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 N2 splitting with a Mo~III triphosphino complex [(PPP)MoI3], 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 N2 molecule, and further splitting to a Mo~IV nitride complex. Preliminary DFT studies support the formation of a bridging Mo~IN2Mo~I dinitrogen dimer evolving to the Mo nitride via a low energy transition state. This example joins a short list of molecular complexes for N2 electrochemical reductive cleavage. It opens a door to electrochemical proton-coupled electron transfer (PCET) conversion studies of N2 to NH3.