Dialkyl titanium complexes that contain a sulfur-linked bis(phenolato) ligand:: The structure of an olefin polymerization catalyst precursor

The sulfur-linked bis(phenol) 2,2′-thiobis(2-tert-butyl-4-methylphenol), tbmpH2, reacted cleanly with titanium tetrachloride to give the orange titanium dichloro complex [Ti(tbmp)Cl2]2 in virtually quantitative yield. Reaction of the dichloro complex [Ti(tbmp)Cl2]2 with methyllithium at low temperature gave the unexpectedly thermally robust, yellow dimethyl complex [Ti(tbmp)Me2]. The reaction of the dichloro complex with benzyl Grignard reagent in pentane afforded the highly crystalline dibenzyl complex [Ti(tbmp)(CH2Ph)2] as a 1,4-dioxane adduct. The single crystal X-ray crystallography revealed a centrosymmetric 1,4-dioxane-bridged molecule that contains two fragments containing six-coordinate titanium centers with the tridentate tbmp ligand in a facial fashion and two η1-benzyl ligands. When [Ti(tbmp)Me2] was activated with B(C6F5)3 in toluene, ethylene was polymerized.