Optical properties of bis(2,6-diphenylphenolate)niobium(V) trichloride: Luminescence from a phenolate to metal charge transfer state

The electronic spectra of NbV(dpp)2Cl3 (dpp−: 2,6-diphenylphenolate−) in the solid state under ambient conditions are reported. The scattered transmission spectrum shows a long-wavelength band (λmax=415 nm) which is assigned to a spin-forbidden (phenolate→NbV) ligand-to-metal charge transfer (LMCT) transition. The complex displays a luminescence (λmax=522 nm; τ∼10−5 s) which is suggested to originate from the LMCT triplet.