ansa-η-Cyclopentadienylimide derivatives of niobium 

Abstract

Treatment of the ansa-bridged η-cyclopentadienylimide compound [Nb{η⁵,κN-C₅H₄ (CH₂)₃N}Cl₂] 1 with MgMeBr gave the binuclear ansa-bridged η-cyclopentadienylimide derivative [MeNb{µ-C₅H₄(CH₂) ₃N}{µ-NCH(CH₂)₂C ₅H₄}NbMe₂] 2. The crystal structure of 2 has been determined. Detailed ¹H and ¹³C NMR studies showed that 2 undergoes an interesting fluxional process involving interchange of two methyl groups under an ansa arch. Reaction of 1 with Na(C₅H₅) gave [Nb{η⁵,κN-C₅H₄ (CH₂)₃N}(η⁵-C₅H ₅)(η¹-C₅H₅)] 3, which is also fluxional and undergoes diverse dynamic processes including exchange between η¹- and η⁵-cyclopentadienyl rings. The compounds [Nb{η⁵,κN-C₅H₄ (CH₂)₃N}(CH₂Ph)₂] and [Nb{η⁵,κN-C₅H₄ (CH₂)₃N}{CH₂C(Me)CH₂ }₂] have also been prepared.

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