Synthesis, structure and theoretical investigation into a homoleptic tris(dithiolene) tungsten

A new homoleptic dithiolene tungsten complex, tris-(1,2-bis(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S'}tungsten, was successfully synthesized via a reaction of the thiophosphate ester and sodium tungstate. The thiophosphate ester was prepared from 3,5-dimethoxybenzaldehyde via benzoin condensation to produce the intermediate 1,2-bis-(3,5-dimethoxyphenyl)-2-hydroxy-ethanone compound, followed by a reaction of the intermediate with phosphorus pentasulfide. FTIR, UV-Vis spectroscopy, H-1 NMR and C-13 NMR and elemental analysis confirmed the product as tris(1,2-bis-(3,5-dimethoxyphenyl)-1,2-ethylenodithiolene-S,S'-tungsten with the molecular formula of C54H54O12S6W. Crystals of the product adopted a monoclinic system with space group of P2(1)/n, where a = 12.756(2) angstrom, b = 21.560(3) angstrom, c = 24.980(4) angstrom and beta = 103.998(3)degrees. Three thioester ligands were attached to the tungsten as bidentate chelates to form a distorted octahedral geometry. Density functional theory calculations were performed to investigate the molecular properties in a generalized-gradient approximation framework system using Perdew-Burke-Ernzerhof functions and a double numeric plus polarization basis set. The HOMO was concentrated on the phenyl ligands, while the LUMO was found along the W(S2C2)(3) rings. The theoretical optical properties showed a slight blue shift in several low dielectric solvents. The solvatochromism effect was insignificant for high polar solvents. (C) 2013 Elsevier B.V. All rights reserved.