Synthetic Studies and Structural Aspects of Dinuclear Sulfur Titanium Compounds

A series of dinuclear sulfur-bridged titanium derivatives [Ti(eta 5-C5Me5)R(mu-S)]2 (R=NMe2 (1), Ph (2), CH2Ph (3), CH2SiMe3 (4)) has been synthesized from the reaction of [Ti(eta 5-C5Me5)Cl(mu-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(eta 5-C5Me5)(mu-S)}2(mu-C3H5)] (5). Contrasting with complexes 1-4, compound 5 exhibits a bridging mu-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(eta 5-C5Me5)(mu-S)}2(mu-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(eta 5-C5Me5)(mu 3-S)]4, along with the corresponding alkane. The synthesis of the dinuclear sulfide derivative [Ti(eta 5-C5Me5)Cl(mu-S)]2 led to the formation of a series of dimetallic alkyl/aryl/amide sulfide-bridged complexes of titanium, [Ti(eta 5-C5Me5)R(mu-S)]2. Hydrogenolysis, using phenyl and trimethylsilyl moieties, resulted in the quantitative generation of the Ti(III) tetrametallic sulfide cluster [Ti(eta 5-C5Me5)(mu 3-S)]4. Alternatively, the treatment of the dimethylamide complex with SiH3Ph, and the reaction of [Ti(eta 5-C5Me5)Cl(mu-S)]2 with MgCl(C3H5), led to the formation of mixed-valence dinuclear systems. image