Synthesis and reactivity of new mixed dicyclopentadienyl Group 4 metal complexes with the doubly bridged bis(dimethylsilanediyl)-cyclopentadiene-(eta(5)-cyclopentadienyl) ligand

The monocyclopentadienyl titanium complex [Ti{(C5H4)(SiMe2)(2)(eta(5)-C5H3) } Cl-3] 3 and the dichloro mixed dicyclopentadienyl Group 4 metal complexes [M(eta(5)-C5R5){(C5H4)(SiMe2)(2)(eta(5)-C5H3)} Cl-2] (R = H; M = Ti 4, Zr 5, Hf 6; R = Me; hi = Ti 7) containing the doubly bridged bis(dimethylsilan ediyl)-cyclopentadiene-(eta(5)-cyclopentadienyl) ligand were prepared in hi gh yields by reaction of the monolithium salt Li[(C5H4)(SiMe2)(2)(C5H3)] 2 with equimolar amounts of TiCl4 or the monocyclopentadienyl complexes [Cp'M Cl3], respectively. Reactions of the chloro complexes with various alkylati ng agents afforded the chloroalkyl [M(eta(5)-C5H5){(C5H4)(SiMe2)(2)(eta(5)- C5H3)} CI] (M = Ti; R = Me 8, Et 9; M = Zr, R = Me 10, Et 11, CH2Ph 12; M = Hf, R = CH2Ph 13) and dialkyl [M(eta(5)-C5R5){(C5H5)(SiMe2)(2)(eta(5)-C5H3 )}Me-2] (M = Ti; R = H 14, Me 15; M = Zr; R = H 16, compounds. Formation of the heterodinuclear complex [Zr(eta(5)-C5H5)Cl-2(eta(5)-C5H3)(SiMe2)(2)(et a(5)-C5H3)Ti(NMe2)(3)] 17 with amine elimination was observed by H-1-NMR sp ectroscopy when complex 5 was reacted with Ti(NMe2)(4). The catalytic activ ity of compounds 3-5 for ethylene polymerization has been studied using MAO as cocatalyst. (C) 1999 Elsevier Science S.A. All rights reserved.