6533b81ffe1ef96bd127725b

RESEARCH PRODUCT

Titanium complexes having chelating diaryloxo ligands bridged by tellurium and their catalytic behavior in the polymerization of ethylene

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A series of titanium complexes having tellurium-bridged chelating bis(aryloxo) ligands, [TiX2{2,2‘-Te(4-R-6-R‘-C6H2O)2}]2 (5b, X = Cl, R = Me, R‘ = tBu; 6a, X = OiPr, R = R‘ = H; 6b, X = OiPr, R = Me, R‘ = tBu), were prepared. 5b and 6b were determined by X-ray crystallography to have chloro- and isopropoxo-bridged dimeric structures. The structural data for these complexes indicated that the Ti−Te coordination bonds were stronger than the similar Ti−S coordination bonds in the corresponding sulfur-bridged complexes. The reaction of (C5R5)TiCl3 (R = H, Me) with 2,2‘-Te(4-R-6-R‘-C6H2OLi)2 gave monocyclopentadienyl derivatives, (C5R5)TiCl{2,2‘-Te(4-Me-6-tBu-C6H2O)2} (7, R = H; 8, R = Me). The monomeric four-legged piano-stool geometry of 8 was revealed by X-ray analysis. Upon addition of methylaluminoxane (MAO), these complexes catalyzed the polymerization of ethylene. The activities of the tellurium-bridged complexes were found to be significantly higher than those of the corresponding methylene-bridged co...