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

Abstract

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)Å, 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)Å, 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.