SYNTHESIS AND REACTIONS OF ETA-CYCLOHEPTATRIENE AND ETA-CYCLOHEPTATRIENYL DERIVATIVES OF ZIRCONIUM AND HAFNIUM

The new compounds [M(eta-C7H8)L2Cl2] (M = Zr, L = PMe3 1; M = Hf, L = PMe3 2; M = Zr, L = PMe2Ph 3; M = Hf, L = PMe2Ph 4; M = Zr, L = PMePh2 5) 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(eta-C7H7)(eta(5)-C9H7)] (M = Zr 6 or Hf 8) which react with trimethylphosphine or 1,2-bis(dimethylphosphino)ethane (dmpe) to form [M(eta-C7H7)(eta(5)-C9H7)(PMe3)] (M = Zr 7 or Hf 9) and [{Hf(eta-C7H7)(eta(-5)-C9H7)}2(mu-dmpe)] 10 respectively. Treatment of 1 or 2 with sodium cyclopentadienide gives [M(eta-C5H5)2{eta(2)-1,2- (or -3,4-) C7H8}(PMe)] [M = Zr 11 or Hf 12). The X-ray crystal structures of 1, 10 and [Zr(eta-C5H5)2(eta(2)-3,4-C7H8)(PMe3)] 11a have been determined.