NEW SILYL-SUBSTITUTED CYCLOPENTADIENYL TITANIUM AND ZIRCONIUM COMPLEXES - X-RAY MOLECULAR-STRUCTURES OF [TICL2(MU-(OSIME(2)-ETA(5)-C5H4))](2) AND 2(MU-[(ETA(5)-C5H4)SIME(2)OSIME(2)(ETA(5)-C5H4)])]

We report the synthesis of 1-(chlorodimethylsilyl)-1-(trimethylsilyl) cyclopentadiene, 1. The reaction of a toluene solution of 1 with one e quivalent of MCl(4) (M = Ti, Zr) leads to the mono(cyclopentadienyl) d erivatives [MCl(3)(eta(5)-C(5)H(4)SiMe(2)Cl)] [M = Ti(2); M = Zr (3)] in 76 and 87% yields, respectively. The same reaction with ZrCl4 in a Zr/Cp molar ratio 1:2 in refluxing methylene dichloride yields the dic yclopentadienyl derivative [ZrCl2(eta(5)-C(5)H(4)SiMe(2)-Cl)(2)], 4, w hereas the related titanium compound cannot be synthesized,by this met hod. These mono- and bis(cyclopentadienyl) complexes are very moisture sensitive and react with water to give different oxo complexes. React ion of one equivalent of water with [TiCl3(eta(5)-C5H4-SiMe(2)Cl)] in toluene takes place with elimination of HCl, resulting in formation of the dinuclear titanium methylsiloxane derivative [TiCl2{mu-(OSiMe(2)- eta(5)-C5H4)}](2), 5, in a quantitative yield, which by further additi on of one equivalent of water gives the mononuclear compound [TiCl2{OS iMe(2)OSiM(2)e(eta(5)-C5H4)}], 6, in very low yield. However the best procedure to obtain 6 (in 45% yield) is the direct reaction of [TiCl3( eta(5)-C(5)H(4)SiMe(2)Cl)] with two equivalents of water. The analogou s reaction of [ZrCl2(eta(5)-C(5)H(4)SiMe(2)Cl)(2)] with one equivalent of water proceeds to give -[(eta(5)-C5H4)SiMe(2)OSiMe(2)(eta(5)C(5)H( 4))]}], 7. Alkylation of [TiCl3(eta(5)-C5H4-SiMe(2)Cl)] with Mg(CH2C6H 5)(2)(THF)(2) leads to the tribenzyl derivative [Ti(CH2C6H5)(3)(eta(5) -C5H4-SiMe(2)Cl)], 8, and alkylation of [TiCl2{mu-(OSiMe(2)-eta(5)-C5H 4)}](2) With MgClMe and Mg(CH2C6H5)(2)-(THF)(2) allows the isolation o f the oxoalkyl complexes [TiR(2){mu-(OSiMe(2)-eta(5)-C5H4)}](2) [R = M e, 9; R = CH2C6H5, 10]. Reaction of [MCl(3)(eta(5)-C(5)H(4)SiMe(2)Cl)] with LiN(SiMe(3))(2) gives the amido complex [TiCl2{N(SiMe(3))(2)(eta (5)-C(5)H(4)SiMe(2)Cl)}], 11, whereas a similar reaction with LiNH(t)B u takes place with simultaneous elimination of HC1 to give the cyclic amido pendant cyclopentadienyl complex [TiCl2{N(t)BuSiMe(2)(eta(5)-C5H 4)}], 12. The molecular structures of [TiCl2{mu-(OSiMe(2)-eta(5)-C5H4) }](2) and 2{mu-[(eta(5)-C5H4)SiMe(2)OSiMe(2)(eta(5)-C5H4)]}] have been determined by X-ray diffraction methods. Complex 5 is a dimer formed by two [Me(2)-SiCpTiCl(2)] fragments bonded by two oxygen bridges, con necting the silicon and titanium atoms from different units. 5 crystal lizes in monoclinic space group P2(1)/n, with a = 9.461(7), b = 10.926 (1), c = 10.507(3) Angstrom, beta = 95.20(2)degrees, and V = 1081(1)An gstrom(3) for Z = 2. The molecular structure of 7 corresponds to a typ ical bent dicyclopentadienyl system. Complex 7 crystallizes in the spa ce group P2(1)/c with a = 13.479(4), b = 8.654(1), c 15.343(5) Angstro m, beta =97.18(2)degrees, and V = 1775(2) Angstrom(3) for Z = 4.