RT info:eu-repo/semantics/article T1 Synthesis and characterization of η5-cyclopentadienyl-silylallyl niobium and tantalum complexes A1 Nicolás Utrilla, María Pilar A1 Royo Gracia, Pascual K1 Niobium K1 Tantalum K1 Imido K1 Cyclopentadienyl K1 Ciencia K1 Química inorgánica K1 Science K1 Chemistry, inorganic AB Reaction of the disilylcyclopentadiene 1,1-[SiMe2(CH2CHdouble bond; length as m-dashCH2)]2C5H4 with NbCl5 gave the new allylsilyl-substituted monocyclopentadienyl niobium complex [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4]. This compound was reacted with LiNHtBu or NH2tBu to give the imido derivative [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl2], which was further alkylated to the imido alkyl complexes [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)R2] (R = Me, CH2Ph) and [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl (CH2Ph)]. Reaction of the imido complexes with the corresponding lithium cyclopentadienides gave the dicyclopentadienyl-imido complexes [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}(NtBu)Cl] (M = Nb, Ta; R = H, Me). Metallocene dichlorides [M(η5-C5R5){η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl2] (M = Nb, Ta; R = H, Me) were easily prepared by reduction with Na/Hg and simultaneous transmetallation of [Ta(η5-C5R5)Cl4] with Li[C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)] and of [Nb{η5-C5H4SiMe2(CH2CHdouble bond; length as m-dashCH2)}Cl4] with Li(C5R5). All of the new compounds have been characterized by elemental analysis, and IR and NMR spectroscopy. PB Elsevier SN 0020-1693 YR 2005 FD 2005 LK http://hdl.handle.net/10017/4177 UL http://hdl.handle.net/10017/4177 LA eng NO Financial support of our work by MCyT (Project MAT2001-1309) is gratefully acknowledged. DS MINDS@UW RD 24-abr-2024