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

The tridentate (OSO-functions) biphenol, 2,2‘-thiobis{4-(1,1,3,3-tetramethylbutyl)phenol}
(tbopH2), reacts with AlMe3 to give [Al2(μ-tbop-κ3O,S,O)2Me2] (1). Alcoholysis of 1 results in
the formation of [Al2(μ-OEt)2(tbop-κ3O,S,O)2] (2). The reaction of 2 with TiCl4 gives the
trimeric complex [Ti3(μ-OEt)2(μ-tbop-κ3O,S,O)2Cl6] (3)·C6H14. Alkylation of 3·C6H14 with LiMe
produces two dimeric complexes, [Ti2(μ-tbop-κ3O,S,O)2Me4] (4) and [Ti2(μ-OE)2(tbop-κ3O,S,O)2Me2] (5)·Et2O. Treatment of [Ti2(μ-OEt)2(tbop-κ3O,S,O)2(OEt)2] with AlMe3 and EtOH afforded
the heterobimetallic species, [Ti2Al2(μ-OEt)6(μ-tbop-κ3O,S,O)2(OEt)4] (6). The structures of
1−6 were confirmed by NMR spectroscopy; complexes 1, 3·C6H14, 5·Et2O, and 6 were further
investigated by X-ray crystallography. Compounds 3−6, when supported on MgCl2 and
activated with aluminum alkyls, effectively polymerize ethene.