Syntheses, crystal structures and spectroscopic characterization of some confacial bioctahedral ditungsten(III) complexes with thioether bridges: [Cl3W(µ-Et2S)3WCl3]·MeCN and [SMe3][Cl3W-(µ-Me2S)2(µ-Cl)WCl3]·EtCN

Abstract

Reduction of WCl₄ with 1 equivalent of Na/Hg in a refluxing thioether solution produced [Cl₃W(µ-L)₃WCl₃][L = tetrahydrothiophene(tht) or Et₂S] in ca. 80% yields. Subsequent recrystallization from CH₂Cl₂ and MeCN gave [Cl₃W(µ-tht)₃WCl₃]1 and [Cl₃W(µ-Et₂S)₃WCl₃]·MeCN 2, respectively. These complexes can also be prepared, in lower yields, by the same reactions carried out at ambient temperature or by refluxing WCl₄, thioether and Na/Hg in toluene solution. Analogous reactions with Me₂S yield exclusively [SMe₃][Cl₃W(µ-Me₂S)₂(µ-Cl)WCl₃] which was recrystallized from EtCN to yield the monosolvate, 3. The structures of 2 and 3 were determined by single-crystal X-ray diffraction, which showed that both complexes possess a confacial bioctahedral framework, with three Et₂S bridges in 2 and two Me₂S and one Cl in 3. The W–W distances, 2.4990(9) in 2 and 2.4752(8)Å3 are compatible with triple bond character, while the W–(µ-S) distances are relatively short. The structure of compound 1 was shown spectroscopically to be analogous to that of 2. Proton NMR spectroscopic studies show that the W(µ-thioether)₃W unit is resistant to attack by halide ions.