A series of new binuclear tungsten(IV) complexes, W2Cl4(μ-SR)2(μ-S)L2 (R = Me, Et, iBu, CH2Ph; L = Me2S or THT), is readily synthesized from the metathetical reaction of WCl4L2 with 1 mol-equiv. of alkylthiotrimethylsilane (Me3Si(SR)). These complexes react with stronger nucleophiles (Ph3P, MeCN, C5H5N, Cl−) under ambient conditions to yield simple disubstituted products. Reaction of W2Cl4(μ-SEt)2(μ-S)(SMe2)2 with PhCH2X (X = Cl, Br) yields [Me2SCH2Ph]2[W2Cl4(μ-SEt)2(μ-S)X2], whilst with stronger alkylating agents, MeSO3F or Et3OBF4, intractable residues result.The series of homologous complexes has been studied by 1H and 13C nmr spectroscopy. When R = Me, two stable configurational isomers are present in solution, whilst only a single isomer exists for more bulky R groups. Trends in the 1H nmr chemical shifts of the methylene and methyl protons of the SEt groups in the complexes W2Cl4(μ-SEt)2(μ-S)L2 allow absolute assignment of the resonances to two magnetically inequivalent thiolato groups.
The complex (Me2S)Cl2W(μ-S)(μ-SEt)2WCl2(Me2S), 1, has been prepared by reaction of [WCl4(Me2S)2] with 1 mol-equiv. 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 2.526(2) Å. The structure was solved by heavy atom methods and refined to R = 0.061 and Rw = 0.061 for 2715 reflections with I ≥ 3σ(1). Crystals of 1 are triclinic, space group [Formula: see text], with a = 9.661(1), b = 10.695(1), c = 13.253(4) Å, α = 61.84(2), β = 66.98(2), and γ = 66.44(1)°, Z = 2.Reaction of 1with 2 mol-equiv. of Ph4PCl in CH2Cl2 solution yields (Ph4P)2[Cl3W(μ-S)(μ-SEt)2WCl3], 2. Crystals of 2 are triclinic, space group [Formula: see text], with a = 10.153(1), b = 13.043(1), c = 21.876(3) Å, α = 95.16(1), β = 96.48(2), and γ = 108.90(1)°, Z = 2. The structure was refined to R = 0.041, Rw = 0.048 for 2384 reflections with I ≥ 3σ(1); 2 also has a confacial bioctahedral structure with a W—W bond length of 2.522(1) Å.