Synthetic Studies and Structural Aspects of Dinuclear Sulfur Titanium Compounds

A series of dinuclear sulfur‐bridged titanium derivatives [Ti(η5‐C5Me5)R(μ‐S)]2 (R=NMe2 (1), Ph (2), CH2Ph (3), CH2SiMe3 (4)) has been synthesized from the reaction of [Ti(η5‐C5Me5)Cl(μ‐S)]2 with the corresponding lithium salt or Grignard reagent. Formulation of 1–4 as symmetric dimers has been confirmed by crystallographic studies. The analogous reaction with Mg(C3H5)Cl afforded the paramagnetic mixed‐valence Ti(III)/Ti(IV) compound [{Ti(η5‐C5Me5)(μ‐S)}2(μ‐C3H5)] (5). Contrasting with complexes 1–4, compound 5 exhibits a bridging μ‐CH2CHCH2 fragment between the titanium atoms, which prevents the formation of a planar Ti2S2 core in the solid‐state structure. Complex 1 reacts with SiH3Ph to give [{Ti(η5‐C5Me5)(μ‐S)}2(μ‐NMe2)] (6), a paramagnetic mixed‐valence Ti(III)/Ti(IV) compound, structurally and electronically similar to 5. Under mild conditions, treatment of compounds 3 and 4 with H2 (1 atm) generates quantitatively the Ti(III) tetrametallic sulfide cluster [Ti(η5‐C5Me5)(μ3‐S)]4, along with the corresponding alkane. The synthesis of the dinuclear sulfide derivative [Ti(η5‐C5Me5)Cl(μ‐S)]2 led to the formation of a series of dimetallic alkyl/aryl/amide sulfide‐bridged complexes of titanium, [Ti(η5‐C5Me5)R(μ‐S)]2. Hydrogenolysis, using phenyl and trimethylsilyl moieties, resulted in the quantitative generation of the Ti(III) tetrametallic sulfide cluster [Ti(η5‐C5Me5)(μ3‐S)]4. Alternatively, the treatment of the dimethylamide complex with SiH3Ph, and the reaction of [Ti(η5‐C5Me5)Cl(μ‐S)]2 with MgCl(C3H5), led to the formation of mixed‐valence dinuclear systems.