Molybdenum Complexes Bearing (Bi)thienyl- or Arylthienyl-Substituted π-Conjugated Spacers: Synthesis, Electrochemical, Spectroscopic and Nonlinear Optical Properties

A series of complexes trans[FMo(N=NCHL)(dppe)(2)][BF4] {L = (bi)thienyl or arylthienyl}, were synthesized and fully characterized by H-1, C-13, P-31 NMR, IR and UV/Vis spectroscopy. The electronic spectra and electrochemical behavior of the complexes were investigated. The electronic absorption spectra of these complexes display a broad low-energy band in the visible region attributable to metal-to-ligand charge-transfer (MLCT) transitions. The electron-conjugated effect with the heterocyclic nucleus led to a notable improvement of visible light absorption and marked changes in the electrochemical behavior. The hyperpolarizabilities beta of the synthesized compounds were evaluated using the hyper-Rayleigh scattering technique.