Benzo[ c]thiophene Chromophores Linked to Cationic Fe and Ru Derivatives for NLO Materials: Synthesis Characterization and Quadratic Hyperpolarizabilities.

η5-Monocyclopentadienyliron(II)/ruthenium(II) complexes of the general formula [M(η5-C5H5)(PP)(L 1)][PF6] {M = Fe, PP = dppe; M = Ru, PP = dppe or 2PPh3; L 1 = 5-[3-(thiophen-2-yl)benzo[ c]thiophenyl]thiophene-2-carbonitrile} have been synthesized and studied to evaluate their molecular quadratic hyperpolarizabilities. The compounds were fully characterized by NMR, FTIR and UV/Vis spectroscopy and their electrochemical behaviour studied by cyclic voltammetry. Quadratic hyperpolarizabilities ( β) were determined by hyper-Rayleigh scattering measurements at a fundamental wavelength of 1500 nm. Density functional theory calculations were employed to rationalize the second-order non-linear optical properties of these complexes. [ABSTRACT FROM AUTHOR]