(I) SYNTHESIS AND REACTIVITY OF RING-BRIDGED BIS(TETRAMETHYL - CYCLOPENTADIENYL)THORIUM ALKYLS AND HYDRIDES. (II) THE REACTION OF A BIS(PENTAMETHYL - CYCLOPENTADIENYL)THORACYCLOBUTANE WITH ALKANES AND ALKENES (CARBON, HYDROGEN, ACTIVATION, METALLACYCLE

The synthesis of the ring-bridged complex (CH(,3))(,2)Si(C(,5)(CH(,3))(,4)H)(,2), Me(,2)Si(Cp''H)(,2), is described. The lithium reagents Me(,2)SiCp(,2)''Li(,2)(.).;2DME and Me(,2)SiCp(,2)''Li(,2)(.)xTHF, x = 1-4, are prepared by the reaction of Me(,2)Si(Cp''H)(,2) with n-butyllithium and dimethoxyethane (DME) or tetrahydrofuran (THF), respectively. The Grignard reagent can also be prepared. Reaction of the lithium reagent with ThCl(,4) results in the formation of Me(,2)SiCp(,2)''ThCl(,2)(.)2LiCl(.)2DME. The reaction of the di- chloride with alkyl lithium reagents results in the formation of Me(,2)Si-.;Cp(,2)ThR(,2), R = n-butyl, CH(,2)C(CH(,3))(,3), CH(,2)Si(CH(,3))(,3), phenyl, and benzyl. Reaction of Me(,2)SiCp(,2)''Th CH(,2)Si(CH(,3))(,3) (,2) with hydrogen yields Me(,2)- SiCp(,2)''ThH(,2) (,2). The catalytic hydrogenation of 1-hexene by Me(,2)Si- Cp(,2)''ThH(,2) (,2) and Cp(,2)'ThH(,2) (,2) (Cp' = (eta)('5)-C(,5)(CH(,3))(,5)) yields turnover.;frequencies, N(,t), of 1.7 x 10('-1) sec('-1) and 1.6 x 10('-4) sec('-1), respectively, under 1 atm of hydrogen. The hydrogenation of trans-2-hexene with Me(,2)SiCp(,2)''ThH(,2) (,2) and Cp(,2)'ThH(,2) (,2) at 0.017 M catalyst and 0.242 M.;in trans-2-hexene and under 1 atm hydrogen yields turnover frequencies of 1.8 x 10('-4) sec('-1) and 2.4 x 10('-5) sec('-1), respectively.;The complex(' )Cp(,2)'ThCH(,2)C(CH(,3))(,2)CH(,2), 3, (Cp' = (eta)('5)-C(,5)(CH(,3))(,5)) reacts with the carbon-hydrogen bonds of methane, tetramethyl- silane (TMS), and tetramethylstannane, to form alkyl complexes of the type Cp(,2)'Th(R) CH(,2)C(CH(,3))(,3) in yields of 45-90%, as determined by ('1)H NMR. The reaction of 3 with TMS was found to be first order in 3 and TMS with a second order rate constant k = 7.0 (+OR-) 0.5 x 10('-5) M('-1) sec('-1) at -10(DEGREES)C. Thermolysis of the complexes Cp(,2)'Th CH(,2)X- (CH(,3))(,3) CH(,2)C(CH(,3))(,3) , X = Sn, Si, yield(' )Cp(,2)'ThCH(,2)X(CH(,3))(,2)CH(,2). The reaction of 3 with trimethylphosphine results in the formation of Cp(,2)'ThCH(,2)P(CH(,3))CH(,2).(' )The reaction of 3 with cyclopropane yields Cp(,2)'Th(CHCH(,2)CH(,2))(,2)(' )and neopentane. Ethylene and propylene insert into the thorium-carbon bond of 3 to form metallacyclohexanes. The reaction of 3 with ethane or 2-methylpropene does not yield stable products.