Cis- and trans-titanium complexes with doubly silyl-bridged dicyclopentadienyl ligands:: molecular structure of [(TiCl)2(μ-O)((SiMe2)2(η5-C5H3)2)]2(μ-O)2

The reaction of TiCl4 with Li-2[(SiMe2)(2)(n(5)-C5H3)(2)] in toluene at room temperature afforded a mixture of cis- and trans- [(TiCl3)(2){(SiMe2)(2)(eta(5)-C5H3)(2)}] in a molar ratio of 1/2 after recrystallization. The complex trans-[(TiCl3)(2){(SiMe2)(2)(eta(5)-C5H3)(2)}] was hydrolyzed immediately by the addition of water to THF solutions to give trans-[(TiCl2)(2)(mu-O){(SiMe2)(2)(eta(5)-C5H3)(2)}] as a solid insoluble in all organic solvents, whereas hydrolysis of cis-[(TiCl3)(2){(SiMe2)(2)(eta(5)-C5H3)2}] under different conditions led to the dinuclear mu-oxo complex cis-[(TiCl2)(2)(mu-O) {(SiMe2)(2)(eta(5)-C5H3)(2)}] and two oxo complexes of the same stoichiometry [(TiCl)(2)(mu-O){(SiMe2)(2)(eta(5)-C5H3)(2)}](2)(mu-O)(2) as crystalline solids. Alkylation of cis- and trans-[(TiCl3)(2){(SiMe2)(2)(mu(5)-C5H3)(2)}] With MgClMe led respectively to the partially alkylated cis-[(TiMe2Cl)(2){(SiMe2)(2)(eta(5)-C5H3)(2)}] and the totally alkylated trans-[(TiMe3)(2){(SiMe2)(2)(eta(5)-C5H3)(2)}] compounds. The crystal and molecular structure of the tetranuclear oxo complex [(TiCl)(2)(mu-O){(SiMe2)(2)(eta(5)-C5H3)(2)}](2)(mu-O)(2) was determined by X-ray diffraction. (C) 1998 Elsevier Science S.A. All rights reserved.