BIS-ETA-CYCLOPENTADIENYL COMPLEXES OF NIOBIUM AND TUNGSTEN WITH SILYLAND STANNYL LIGANDS

The thermal reaction of [Nb(eta-C5H5)(2)H-3] with SiMe(3)H gives [Nb(e ta-C5H5)(2)H-2(SiMe(3))], which readily loses SiMe(3)H to give the [Nb (eta-C5H5)(2)H] fragment, which can be trapped by PMe(3) to give [Nb(e ta-C5H5)(2)(SiMe(3)XPMe(3))]. The reaction of [Nb(eta-C5H5)(2)H(eta-H2 C=CHPh)] with SiMe(3)H yields the bis-silyl [Nb(eta-C5H5)(2)H(SiMe(3)) (2)], which also readily loses SiMe(3)H; thus reaction of [Nb(eta-C5H5 )(2)H(SiMe(3))(2)] with PMe(3) gives [Nb(eta-C5H5)(2)(SiMe(3))(PMe(3)) ]. The reaction of [{(W(eta-C5H5)(2)HLi}] with SnMe(3)Cl gives [W(eta- C5H5)(2)H(SnMe(3))], which is deprotonated by (n)BuLi to give the weak ly nucleophilic anion [W(eta-C5H5)(2)(SnMe(3))](-). The reaction of [W (eta-C5H5)(2)H-2] with SnMe(2)Cl(2) in the presence of Et(3)N gives [W (eta C5H5)(2)(SnMe(2)Cl)(2)], which is readily methylated to yield the tungsten bis-stannyl [W(eta-C5H5)(2)(SnMe(3))(2)].