Synthesis and reactions of η-cycloheptatriene and η-cycloheptatrienyl derivatives of zirconium and hafnium

Abstract

The new compounds [M(η-C₇H₈)L₂Cl₂](M = Zr, L = PMe₃1; M = Hf, L = PMe₃2; M = Zr, L = PMe₂Ph 3; M = Hf, L = PMe₂Ph 4; M = Zr, L = PMePh₂5) have been synthesised by reduction of MCl₄ using sodium amalgam in the presence of the tertiary phosphine and cycloheptatriene. Lithium indenide reacts with the triene compounds to give [M(η-C₇H₇)(η⁵-C₉H₇)](M = Zr 6 or Hf 8) which react with trimethylphosphine or 1,2-bis(dimethylphosphino)ethane (dmpe) to form [M(η-C₇H₇)(η⁵-C₉H₇)(PMe₃)](M = Zr 7 or Hf 9) and [{Hf(η-C₇H₇)(η⁵-C₉H₇)}₂(µ-dmpe)]10 respectively. Treatment of 1 or 2 with sodium cyclopentadienide gives [M(η-C₅H₅)₂{η²-1,2-(or -3,4-) C₇H₈}(PMe₃)][M = Zr 11 or Hf 12). The X-ray crystal structures of 1, 10 and [Zr(η-C₅H₅)₂(η²-3,4-C₇H₈)(PMe₃)]11a have been determined.