SYNTHESIS OF BIS(TERT-BUTYL)CYCLOPENTADIENYL DERIVATIVES OF TITANIUM AND ZIRCONIUM - NMR-SPECTRA AND DYNAMIC BEHAVIOR OF THE BASE-FREE [ZR(1,3-(T)BU(2)-ETA(5)-C5H3)(CH(2)PH)(2)](+) CATION

Reaction of Si(1,3-(t)Bu(2)-C5H3)Me(3) with MCl(4) (M = Ti, Zr) in toluene or hexane at room temperature affords the new trichloromonociclopentadienyl-type derivatives [M(1,3-(t)Bu(2)-eta(5)-C5H3)Cl-3] (M = Ti (2), Zr (3)]. Treatment of complexes 2 and 3 with appropriate alkylating reagents in hexane gives the 1,3-di(tert-butyl)cyclopentadienyl trialkyl titanium and zirconium complexes [M(1,3-(t)Bu(2)-eta(5)-C5H3)R(3)][M = Ti, R = CH3 (4), CH(2)Ph (5); M = Zr, R = CH3 (6), CH(2)Ph (7), CH(2)CMe(2)Ph (8)]. Interestingly, when 2 reacts with 3.1 equivalents of LiCH(2)CMe(2)Ph in hexane at room temperature the ring-tert-butyl-metallated complex [Ti(1-(t)Bu-3-CMe(2)CH(2)-eta(5)-C5H3) (CH(2)CMe(2)Ph)(2)] (9) was isolated in 90% yield. The cationic mono(1,3-di-(tert-butyl)cyclopentadienyl dibenzyl zirconium species [Zr(1,3-(t)Bu(2)-eta(5)-C5H3)(CH(2)Ph)(2)](+), generated in situ by reaction of the tribenzyl complex 7 with B(C6F5)(3) or [CPh(3)](+)[B(C6F5)(4)](-) reagents, is reported and their dynamic NMR behaviour in CD2Cl2 solutions at low temperatures is studied.