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

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. © 1997 Elsevier Science S.A