DIMERIC STRUCTURES OF CP'TICL2 COMPOUNDS WITH BULKY SUBSTITUENTS AT THE CYCLOPENTADIENYL RINGS

The complexes [(eta(5)-C5Me4Ph)TiCl(mu-Cl)](2) (1) and [(eta(5)-C5Bn5) TiCl(mu-Cl)](2) (2) (Bn = benzyl) were obtained by the reaction of TiC l3 and the corresponding alkali metal cyclopentadienides in a THF-tolu ene mixture. The X-ray diffraction single-crystal analysis revealed th at both compounds form centrosymmetric dimers bridged via a pair of ch loride ligands. Compound 1 crystallizes in the monoclinic space group P2(1)/n (No. 14; a = 11.387(3) Angstrom, b = 16.496(2) Angstrom, c = 8 .383(2) Angstrom, beta = 110.786(15)degrees, V = 1 472.2(6) Angstrom(3 ), Z = 2), and compound 2 in the monoclinic space group P2(1)/c (No. 1 4; a = 18.967(5) Angstrom, b = 10.7190(10) Angstrom, c = 17.996(5) Ang strom, beta = 116.747(15)degrees V = 3 267.2(13) Angstrom(3), Z = 2). Common features of the structures differ only negligibly. The Ti-Ti di stance (in 1 3.3345(11) Angstrom,in 2 3.374(2) Angstrom) is considerab ly shorter than in paramagnetic dimeric titanocene monochlorides (3.91 -3,95 Angstrom). The compounds are diamagnetic, probably due to spin-p aired d(1) electrons.