STUDIES ON ORGANOLANTHANIDE COMPLEXES .55. SYNTHESIS OF FURAN-BRIDGEDBIS(CYCLOPENTADIENYL) LANTHANIDE AND YTTRIUM CHLORIDES, AND LIGAND AND METAL TUNING OF REACTIVITY OF ORGANOLANTHANIDE HYDRIDES (IN-SITU)

Four new complexes [{Ln[OCH(CH2C5H4)CHCHCH(CH2C5H4)]Cl}2] (Ln = Y, Yb, Sm or Nd) were synthesised by using furan-bridged bis(cyclopentadiene s) as ancillary ligands and characterized by elemental analyses, mass, IR and H-1 NMR spectroscopy. The spectra indicate that these complexe s are chloride-bridged dimers and the two furan-bridged cyclopentadien yl rings co-ordinate to each metal in a chelating fashion with intramo lecular co-ordination between the oxygen atom and the metal. The effec ts of the bridging chain and the central metal upon the reactivity of organolanthanide hydrides generated in situ from the [Ln(C5H5)2Cl]-NaH system were investigated. The reactivity can be tuned not only by var ying the ligands but also by taking advantage of the lanthanide contra ction. The ligand tunability varies for different reactions. More reac tive organolanthanide hydride species (in situ) can be obtained by bot h 'ligand tuning' and 'metal tuning', i.e. by selecting the appropriat e ancillary ligands and the early lanthanide metals.