6533b821fe1ef96bd127b9ae

RESEARCH PRODUCT

Zirconium and hafnium complexes of the thio(bisphenolato) ligand: synthesis, structural characterization and testing as 1-hexenepolymerizationcatalysts

subject

description

Thio(bisphenolato) complexes of the type [M2(mu-tbop-kappa3O,S,O)2Cl4] [M = Zr 1, Hf 2 and tbop = 2,2-thiobis{4-(1,1,3,3-tetramethyl-butyl)phenolate}] were prepared by HCl elimination from tbopH2 and MCl4. Substitution of the chlorides in 1 and 2 by 2,6-diisopropylphenolato groups (dipp) generates new compounds [M2(mu-tbop-kappa3O,S,O)2(dipp)4] (M = Zr 3, Hf 4). The structures of 1-4 were confirmed by NMR spectroscopy; complexes 3 and 4 were further investigated by X-ray crystallography. These studies showed 1-4 to be dimers either in the solid state or in solution and to have metal centers adopting distorted octahedral geometry. However treatment of MCl4 with [Al2(mu-OEt)2(tbop-kappa3O,S,O)2] or [Al2(mu-tbop-kappa3O,S,O)2Me2] gave heterotrinuclear complexes [M(tbop-kappa3O,S,O)2Cl2(mu-AlX2)2] (M = Zr, X = Cl 5, X = Me 7 and M = Hf, X = Cl 6, X = Me 8) for which the single-crystal X-ray diffraction analysis showed zirconium and hafnium centers to have eight-coordinate dodecahedral geometry. Complexes 1-6 after activation with aluminium alkyls and supporting on MgCl2 showed a lack of activity in the ethene polymerization process and moderate activity towards 1-hexene producing high molecular weight atactic poly(1-hexenes).