Vikram D. Patel

Mixed oxidation state confacial bioctahedral complexes of tungsten possessing strong metal–metal interactions. Part 2. Synthesis, X-ray crystal structure and electron spin resonance studies of the WIII/WIV complex [AsPh4]2[Cl3W(µ-Cl)(µ-SPh)2WCl3]·1.4CH2Cl2

The mixed oxidation state dimeric tungsten(III/IV) species [(Me2S)Cl2W(µ-Cl)(µ-SPh)2WCl2(SMe2)] and [Cl3W(µ-Cl)(µ-SPh)2WCl3]2– have been synthesized. A single-crystal X-ray diffraction study of the compound [AsPh4]2[Cl3W(µ-Cl)(µ-SPh)2WCl3]·1.4CH2Cl2(1) shows that the two tungsten atoms have identical environments, imposed by a crystallographic two-fold axis passing through the bridging chlorine atom. Structural parameters indicate a strong tungsten–tungsten bond of length 2.519(2)A, in a distorted confacial bioctahedral structure. Crystals are monoclinic, space group C2/c, with unit-cell dimensions (at 296 K)a= 22.584(15), b= 12.174(4), c= 24.359(15)A, β= 104.15(3)°, and Z= 4. The structure was refined to R= 0.072 (R′= 0.096) for 3 327 unique reflections. E.s.r. spectra of (1) as a powdered solid at 77 and 298 K and as a frozen solution in CH2Cl2 at 77 K were obtained at X-band frequencies. The spectra have been interpreted as a rhombic S=½ system, and have been simulated on this basis. The spectra are characterized by a large anisotropy in the g values, with one g value considerably greater than 2.

The crystal structure of di-µ-ethanethiolato-µ-sulphido-bis[dichloro-(tetrahydrothiophen)tungsten(IV)(W–W)]: a confacial bioctahedral complex with a tungsten-to-tungsten bond

The complex [(C4H8S) Cl2W(µ-S)(µ-SEt)2WCl2(SC4H8)] has been prepared by reaction of [WCl4(C4H8S)2] with one mole equivalent of SiMe3(SEt) in CH2Cl2 solution. A single-crystal X-ray diffraction study shows that the molecule has a confacial bioctahedral structure with a W–W bond length of 2.524(1)A. The structure has been solved by heavy-atom methods from automated diffractometer data, and refined to R 0.025 (R′ 0.037) for 1 593 reflections. The complex crystallizes in the orthorhombic system, space group Pnam, with a= 10.592(3), b= 12.618(4), c= 17.430(6)A, and Z= 4.