SYNTHESES, CRYSTAL-STRUCTURES AND SPECTROSCOPIC CHARACTERIZATION OF SOME CONFACIAL BIOCTAHEDRAL DITUNGSTEN(III) COMPLEXES WITH THIOETHER BRIDGES - [CL3W(MU-ET2S)3WCL3].MECN AND [SME3][CL3W-(MU-ME2S))2(MU-CL)WCL3].ETCN TRIS(MU-DIETHYL SULFIDE)-BIS[TRICHLOROTUNGSTEN(III)]-ACETONITRILE(1/1) AND TRIMETHYLSULFONIUM MU-CHLORO-BIS-MU-DIMETHYL SULFIDE)-BIS[TRI-CHLOROTUNGSTATE(III)]-PROPIONITRILE (1/1)

Reduction of WCl4 with 1 equivalent of Na/Hg in a refluxing thioether solution produced [Cl3W(mu-L)3-WCl3][L = tetrahydrothiophene(tht) or Et2S] in ca. 80% yields. Subsequent recrystallization from CH2Cl2 and MeCN gave [Cl3W(mu-tht)3WCl3] 1 and [Cl3W(mu-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(mu-Me2S)2(mu-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) angstrom 3 are compatible with triple bond character, while the W-(mu-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(mu-thioether)3W unit is resistant to attack by halide ions.