Theoretical studies of ground and excited electronic states of complexes M(CO)4(phen) (M = Cr, Mo, W; phen = 1,10-phenanthroline)

Electronic absorption and emission data of M(CO)4(phen) complexes, where M = Cr, Mo or W; phen=1,10-phenanthroline are reported using density functional theory (DFT). Electronic absorption spectra of [M(CO)4(phen)] show a strong band in the visible region of the spectrum, whose metal to ligand charge transfer (MLCT) M → phen and M → COax character is indicated by high molar absorptivity. This assignment is investigated by theoretical calculations, which differ from the early interplay of M → L metal to ligand charge transfer MLCT and ligand-filed (LF) electronic transitions, occurring between d-orbitals. The phosphorescence of each complex was identified as a lowest, triplet metal to ligand charge transition (MLCT) around 740 nm.