Synthesis, Structures, and Catalytic Properties of Constrained Geometry Cyclopentadienyl-phenoxytitanium Dichlorides

Abstract

The synthesis of four new bidentate ligands, 2-(3,4-diphenylcyclopentadienyl)-6-phenylphenol ((DCPP)H 2, 7 ), 2-(3,4-diphenylcyclopentadienyl)-6- tert -butylphenol ((DCBP)H 2, 8 ), 2-(3,4-diphenylcyclopentadienyl)-4, 6-di- tert -butylphenol (DCDBP)H 2, 9 ), and 2-(3,4-diphenylcyclopentadienyl)-6-methylphenol ((DCMP)H 2, 10 ), as well as their corresponding constrained geometry cyclopentadienyl-phenoxytitanium dichlorides ((DCPP)TiCl 2 ( 11 ), (DCBP)TiCl 2 ( 12 ), (DCDBP)TiCl 2 ( 13 ), and (DCMP)TiCl 2 ( 14 )), are described. Complexes 11 − 14 were synthesized from the reaction of TiCl 4 with the corresponding dilithio salt of the ligand. Molecular structures of 11 and 12 were determined by single-crystal X-ray diffraction studies. The Cp(cent)−Ti−O angles of 107.4° for 11 and 106.7° for 12 reveal their sterically open features as catalyst precursors. When activated with i Bu 3 Al and Ph 3 C + B(C 6 F 5 ) 4 -, complexes 11 − 14 exhibit reasonable catalytic activity for ethylene polymerization, producing polyethylenes with moderate molecular weights and melt transition temperatures. Compounds 12 and 13 show good catalytic activity for copolymerization of ethylene with 1-hexene.