Synthesis and reactivity of imido niobium complexes containing the functionalized (dichloromethylsilyl)cyclopentadienyl ligand

摘要

The mobium complex [(NbCpCl4)-Cl-Cl] (CPCl=eta(5)-C5H4(SiCl2Me)) (1) with a functionalized (dichloromethylsilyl)cyclopentadienyl ligand was isolated by the reaction of [NbCl5] with C5H4(SiCl2Me)(SiMe3). Complex 1 was a precursor for the imido silylamido derivative [(NbCpCl2)-Cl-N(NtBu)] (Cp-N=eta(5)-C5H4[SiClMe(NHtBu)]) (2) after addition of LiNHtBu, which subsequently gave the dichlorosilyl compound [(NbCpCl2)-Cl-Cl(NtBu)] (3) when reacted with SiCl3Me. Addition of LiNHtBu to complex 2 gave the niobium amido complex [(NbCpCl)-Cl-N(NHtBu)(NtBu)] (4), which slowly evolved with exchange of the niobium-amido and the silicon-chloro groups to give the dichloroniobium complex [(NbCpCl2)-Cl-NN(NtBu)] (Cp-NN=eta(5)-C5H4[SiMe(NHtBu)(2)]) (5). Reaction of 2 with excess LiNHtBu gave the silyl-eta-amido constrained geometry complexes [Nb{eta(5)-C5H4[SiMe(NHtBu)(-eta-NtBu)]}(NHtBu)(NtBu)] (6) and [Nb{eta(5)-C5H4[SiClMe(-eta-NtBu)]}(NHtBu)(NtBu)] (7), whereas addition of one equimolecular amount of LiNHtBu to 5 in C6D6 afforded complex [(NbCpCl)-Cl-NN(NHtBu)(NtBu)] (8). All of the new complexes were characterized by H-1, C-13 and Si-29 NMR spectroscopy. (c) 2006 Elsevier B.V. All rights reserved.