Preparation and chemical behaviour of halodicyclopentadienyl-zirconium(III) and halodicyclopentadienyl-hafnium(III)

Abstract

Reduction of (η5-C5H5)2MCl2 (M = Zr, Hf) with one equivalent of Na/Hg gives [(η5-C5H5M (μ-Cl)]2. The zirconium(III) complex is also obtained from reactions between LiCp and [ZrCl3L2]2 (L2 = 2P-n-Bu3, dppe) or solutions of ZrCl4 previously reduced with Na/Hg. These zirconium(III) and hafnium(III) complexes are oxidized by AgBF4 or TlBF4 to the cationic [(η5-C5H5M(μ-Cl)]22+ complexes, which react with monodentate ligands to give [(η5-C5H5)2MClL]+ (L = OPPh3, NHPh2) and with bidentate ligands to give dinuclear cationic derivatives [(η5-C5H5)2MCl]2(μ-LL)2+ (LL-dppe, 2,2′-bipyridine). Similar complexes can also be obtained from (η5-C5H5)2MCl2 by halide abstraction with a silver salt. Oxidation of zirconium(III) and hafnium(III) derivatives with halogens gives (η5-C5H5)2MClX (X = Cl, Br) and [(η5-C5H5)2ZrCl(OPPh3)]I3. Conductivity, magnetic susceptibility and IR and NMR data are discussed.