Axial Ligand Substituted Nonheme Fe^IVO Complexes: Observation of Near-UV LMCT Bands and FeO Raman Vibrations

Axial ligand substitution of a mononuclear nonheme oxoiron(IV) complex, [FeIV(O)(TMC)(NCCH3)]2+ (1) (TMC = 1,4,8,11-tetramethyl-1,4,8,11-tetraazacyclotetradecane), leads to the formation of new FeIVO species with relatively intense electronic absorption features in the near-UV region. The presence of these near-UV features allowed us to make the first observation of FeO vibrations of S = 1 mononuclear nonheme oxoiron(IV) complexes by resonance Raman spectroscopy. We have also demonstrated that the reactivity of nonheme oxoiron(IV) intermediates is markedly influenced by the axial ligands.