(Electro)chemical N Splitting by a Molybdenum Complex with an Anionic PNP Pincer-Type Ligand.

Molybdenum(III) complexes bearing pincer-type ligands are well-known catalysts for N-to-NH reduction. We investigated herein the impact of an anionic PNP pincer-type ligand in a Mo(III) complex on the (electro)chemical N splitting ([MoCl], , H = 2,6-bis((di--butylphosphaneyl)methyl)-pyridin-4-one). The increased electron-donating properties of the anionic ligand should lead to a stronger degree of N activation. The catalyst is indeed active in N-to-NH conversion utilizing the proton-coupled electron transfer reagent SmI/ethylene glycol. The corresponding Mo(V) nitrido complex exhibits similar catalytic activity as and thus could represent a viable intermediate. The Mo(IV) nitrido complex is also accessible by electrochemical reduction of under a N atmosphere. IR- and UV/vis-SEC measurements suggest that N splitting occurs via formation of an "overreduced" but more stable [((N)Mo)μ-N] dimer. In line with this, the yield in the nitrido complex increases with lower applied potentials.