Homo- and Heterometallic Aluminum and Titanium Complexes of Tridentate (OSO) Ligand:  Synthesis, Structure, and Catalytic Activity

Abstract

The tridentate (OSO-functions) biphenol, 2,2‘-thiobis{4-(1,1,3,3-tetramethylbutyl)phenol} (tbopH 2 ), reacts with AlMe 3 to give [Al 2 (μ-tbop-κ 3 O,S,O) 2 Me 2 ] ( 1 ). Alcoholysis of 1 results in the formation of [Al 2 (μ-OEt) 2 (tbop-κ 3 O,S,O) 2 ] ( 2 ). The reaction of 2 with TiCl 4 gives the trimeric complex [Ti 3 (μ-OEt) 2 (μ-tbop-κ 3 O,S,O) 2 Cl 6 ] ( 3 )·C 6 H 14 . Alkylation of 3 ·C 6 H 14 with LiMe produces two dimeric complexes, [Ti 2 (μ-tbop-κ 3 O,S,O) 2 Me 4 ] ( 4 ) and [Ti 2 (μ-OE) 2 (tbop-κ 3 O,S,O) 2 Me 2 ] ( 5 )·Et 2 O. Treatment of [Ti 2 (μ-OEt) 2 (tbop-κ 3 O,S,O) 2 (OEt) 2 ] with AlMe 3 and EtOH afforded the heterobimetallic species, [Ti 2 Al 2 (μ-OEt) 6 (μ-tbop-κ 3 O,S,O) 2 (OEt) 4 ] ( 6 ). The structures of 1 − 6 were confirmed by NMR spectroscopy; complexes 1, 3 ·C 6 H 14, 5 ·Et 2 O, and 6 were further investigated by X-ray crystallography. Compounds 3 − 6, when supported on MgCl 2 and activated with aluminum alkyls, effectively polymerize ethene.