Synthesis of organometallic Ru(II) and Fe(II) complexes containing fused rings hemi-helical ligands as chromophores. Evaluation of non-linear optical properties by HRS

Abstract

A new family of three-legged piano stool structured organometallic compounds containing the fragment η 5-cyclopentadienyl-ruthenium(II)/iron(II) has been synthesized to evaluate the existence of electronic metal to ligand charge transfer upon coordination of the novel benzodithiophene ligands ( BDT), benzo[1,2- b;4,3- b′]dithiophen-2-carbonitrile ( L1) and benzo[1,2- b;4,3- b′]dithiophen-2′nitro-2-carbonitrile ( L2). All the compounds were characterized by 1H, 13C, 31P NMR, IR and UV–Vis. spectroscopies and their electrochemistry studied by cyclic voltammetry. The X-ray structures of [Ru(η 5-C 5H 5)(PPh 3) 2(NCC 10H 5S 2)][PF 6] ( 1Ru), [Ru(η 5-C 5H 5)(PPh 3) 2(NCC 10H 5S 2)][CF 3SO 3] ( 1′ Ru), [Ru(η 5-C 5H 5)(DPPE)(NCC 10H 5S 2)][PF 6] 2Ru and [Fe(η 5-C 5H 5)(DPPE)(NCC 10H 5S 2)][PF 6] ( 2Fe) were determined by X-ray diffraction showing centric crystallization on groups P 1 ¯ and P2 1/ n, respectively. Quadratic hyperpolarizabilities ( β) of some of the complexes ( 2Fe, 2Ru and 3Fe) have been determined by hyper-Rayleigh scattering (HRS) measurements at a fundamental wavelength of 1500 nm, to minimize the probability of fluorescence due to two-photon absorption and to reduce the effect of resonance enhancement, in order to estimate static β values.