Manganese Nitride Complexes in Oxidation States III, IV, and V: Synthesis and Electronic Structure

The synthesis and characterization of a series of manganese nitrides in a tripodal chelating tris­(carbene) ligand framework is described. Photolysis of [(TIMEN^xyl)­Mn­(N₃)]⁺ (where TIMEN^xyl = tris­[2-(3-xylylimidazol-2-ylidene)­ethyl]­amine) yields the isolable molecular Mn^IV nitride, [(TIMEN^xyl)­Mn­(N)]⁺. Spectroscopic and DFT studies indicate that this Mn^IV d³ complex has a doublet electronic ground state. The metal-centered one-electron oxidation of this Mn^IV species results in formation of the pentavalent Mn^V nitride, [(TIMEN^xyl)­Mn­(N)]²⁺. Unlike previously reported, tetragonal Mn^V nitrides with a d², nonmagnetic S = 0 ground state, this trigonal bipyramidal complex has a triplet ground state S = 1. One-electron reduction of [(TIMEN^xyl)­Mn­(N)]⁺ produces the neutral, nonmagnetic trivalent [(TIMEN^xyl)­Mn­(N)] species with a d⁴ low-spin, S = 0, ground state.