The preparation and structural characterization of a series of group 4 complexes supported by 2,2'-phenylphosphinobis(4,6-di-tert-butylphenolate) ([OPO]2-) are described. The reaction of either H2[OPO] with Ti(OR)4 (R = Et, iPr) or Li2[OPO] with TiCl4(THF)2 produced yellowish-orange crystals of Ti[OPO]2, regardless of the stoichiometry of the starting materials employed. Comproportionation of the bis-ligand complex Ti[OPO]2 with 1 equiv of TiCl4(THF)2 led to the formation of [OPO]TiCl2(THF) as brownish-red crystals. Surprisingly, treatment of H2[OPO] with [(Me3Si)2N]2MCl2 (M = Zr, Hf), irrespective of the molar ratio, generated colorless crystals of the corresponding bis-ligand complex [OPO]2M(OH2) as an aqua adduct. The solution and solid-state structures of these group 4 complexes were all characterized by multinuclear NMR spectroscopy and X-ray crystallography, respectively.

Keywords: Lithium / Iron / O,P ligands / Cluster compoundsThe preparation and characterization of lithium and iron(II) complexes containing a potentially tridentate biphenolate phosphane ligand are reported. Deprotonation of 2,2Ј-phenylphosphanyl-bis(4,6-di-tert-butylphenol) (H 2 L Ph ) with one or two equivalents of nBuLi in diethyl ether solutions at -35°C produces binuclear {Li(HL Ph )(OEt 2 )} 2 or tetranuclear Li 4 (L Ph ) 2 (OEt 2 ) 3 , respectively. An X-ray study of {Li(HL Ph )-(OEt 2 )} 2 showed it to be a C i -symmetric dimer composed of two Li(HL Ph )(OEt 2 ) units linked with dative O-Li bonds in-