SYNTHESIS AND REACTIVITY OF [(AMIDOSILYL)CYCLOPENTADIENYL]TITANIUM AND [(AMIDOSILYL)CYCLOPENTADIENYL]ZIRCONIUM COMPLEXES - X-RAY MOLECULAR-STRUCTURE OF ETA(1)-C(5)H(4)SIME(2)(MU-O))CL-2(H2N(CHME)PH)](2)

New half-sandwich (amidosilyl)cyclopentadienyl complexes of titanium(I V) and zirconium(IV) were synthesized from the chlorosilyl-substituted cyclopentadienyl precursors [M(eta(5)- C(5)H(4)SiMe(2)Cl)Cl-3] (M = T i(1a), Zr(1b)). The reaction of [Ti(eta(5)-C(5)H(4)SiMe(2)Cl)Cl-3] (1a ) with LiNHR in the presence of NEt(3) gives the [Ti(eta(5):eta(1)-C(5 )H(4)SiMe(2)NR)Cl-2] (R = (t)Bu (2a), (+/-)-CH(Me)Ph (3a)) complexes. Similarly, the addition of 2 equiv of LiN(SiMe(3))(2) to complex la af fords the diamido derivative [Ti(eta(5)-C(5)H(4)SiMe(2)Cl)Cl{N(SiMe(3) )(2)}2] (4a). The amidotitanium complex ta(5):eta(1)-C(5)H(4)SiMe(2)NH (t)Bu)Cl-2(NH(t)Bu)] (5a) is prepared, in low yield, by reacting 1.0 w ith NH(2)(t)Bu in a 1:3 molar ratio. In this reaction, the presence of 2a is also detected. The same complexes 2a and 3a may also be obtaine d by reaction of the trichloro compound 1a with NH(2)R and NEt(3) in a 1:1:2 molar ratio. The reaction of 2a with Tl(C5H5) gives the mixed-d icyclopentadienyl derivative a(5):eta(1)-C(5)H(4)SiMe(2)N(t)Bu)(eta(5) -C5H5)Cl] (6a). The dialkyl derivatives [Ti(eta(5):eta(1)-C(5)H(4)SiMe (2)NR)R'(2)] (R = (t)Bu, R' = CH3 (7a), CH(2)Ph (8a); R = CH(Me)Ph, R' = CH3 (9a), CH(2)Ph (10a)) have been isolated by reaction of 2 equiv of MgClMe or 1 equiv of Mg(CH(2)Ph)(2) .2THF with the dichlorides 2a a nd 3a. The analogous reaction of 2a with 1 equiv of MgCl(CH(2)Ph) affo rds the chloro alkyl derivative (eta(5):eta(1)-C(5)H(4)SiMe(2)N(t)Bu)- (CH(2)Ph)Cl] (11a). The reaction of complexes 2a and 3a with CO2 leads to their conversion into the reported oxo derivative [Ti{mu-(eta(5)-C (5)H(4)SiMe(2)O)}Cl-2](2) with elimination of alkyl isocyanate O = C = NR (R = (t)Bu, (+/-)-CH(Me)Ph) as the unique organic product. Additio n of 1 equiv of LiN(SiMe(3))(2) to a diethyl ether solution of [Zr(eta (5)-C(5)H(4)SiMe(2)Cl)Cl-3] (1b) gives the monoamido derivative [Zr(et a(5)-C(5)H(4)SiMe(2)Cl)Cl-2{N(SiMe(3))(2)}] (2b). The related reaction of the zirconium derivative 1b with LiNH(t)Bu in the presence of NEt( 3) produces a mixture of two compounds, [Zr(eta(5):eta(1)-C(5)H(4)SiMe (2)N(t)Bu)Cl-2] (3b) and [Zr(mu(5)-C(5)H(4)SiMe(2)NH(t)Bu)Cl-3(NEt(3)) ] (4b). Pure 3b can be isolated by recrystallization of this mixture, but attempts to isolate the pure compound 4b were unsuccessful. The an alogous reaction of 1b with 1 equiv of LiNHCH(Me)Ph in the presence of NEt(3) gives the related zirconium compound (eta(5)-C(5)H(4)SiMe(2)-[ NH(CHMe)Ph]}Cl-3(NEt(3))] (5b), which cannot be obtained as an analyti cally pure solid and is identified by H-1 NMR spectroscopy. When water -saturated toluene is used to prepare 5b, the oxo-zirconium derivative eta(1)-C(5)H(4)SiMe(2)(mu-O))Cl-2{H2N(CHMe)Ph}](2) (6b) is obtained b y slow precipitation. Compound 6b has been characterized by X-ray crys tallography.