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.