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 [(TIMENxyl)Mn(N-3)](+) (where TIMENxyl = tris[2-(3-xylylimidazol-2-ylidene)ethyl]amine) yields the isolable molecular Mn-IV nitride, [(TIMENxyl)Mn(N)](+). Spectroscopic and DFT studies indicate that this Mn-IV d(3) 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, [(TIMENxyl))Mn(N)](2+). Unlike previously reported, tetragonal Mn-V nitrides with a d(2), nonmagnetic S = 0 ground state, this trigonal bipyramidal complex has a triplet ground state S = 1. One-electron reduction of [(TIMENxyl)Mn(N)](+) produces the neutral, nonmagnetic trivalent [(TIMENxyl)Mn(N)] species with a d(4) low-spin, S = 0, ground state.