Ansa-bridged η-cyclopentadienyl imido and amido derivatives of titanium, zirconium, niobium and molybdenum

Article abstract of DOI:10.1016/S0022-328X(97)00022-3

An improved synthesis of the ligand precursor {[C₅H₄(SiMe₃)](CH₂)₃N(SiMe₃)₂} is described. It has been used to prepare the ansa compounds {Ti[η:σ-C₅H₄(CH₂)₃N(SiMe₃)]Cl₂}, {Ti[η-C₅H₄(CH₂)₃(μ-N)]Cl)}₂, {Zr[η:σC₅H₄(CH₂)₃N(SiMe₃)]Cl₂}, {Zr[η:σ-C₅H₄(CH₂)₃N(SiMe₃)](SMe₂)Cl₂} and {Mo[η:σ-C₅H₄(CH₂)₃N(SiMe₃)](PMe₃)Cl₃). Treatment of {Nb[η:σ-C₅H₄(CH₂)₃N]Cl₂} with MeMgBr gives the dimer {MeNb[η-C₅H₄(CH₂)₃(μ-N)(μ-σ(N):η²-(N,C)-NCH(CH₂)₂-η-C₅H₄)]NbMe₂} whose crystal structure has been determined. The new compounds {Nb[η:σ-C₅H₄(CH₂)₃N](η-C₅H₅)(σ-C₅H₅)}, {Nb[η:σ-C₅H₄(CH₂)₃N](CH₂C₆H₅)₂} and Nb[η:σ-C₅H₄(CH₂)₃N][CH₂C(CH₃)CH₂]₂} have also been prepared. The zirconium compounds together with methylaluminoxane act as catalysts for ethylene and propylene polymerisation.