SYNDIOSPECIFIC POLYMERIZATION OF STYRENE WITH Ar[O,O/NH]Cp*TiCl ACTIVATED WITH MMAO

 A series of titanium complexes ArO, E]Cp^*TiCl (Cp^* = C₅Me₅, Ar = 1,2-phenylene, E = NH (1a); Ar = 1,2-phenylene, E = O (1b); Ar = 2,2′-diphenylene, E = O (1c); Ar = 2,2′-dinaphthalene, E = O (1d)) has been prepared by the reaction of corresponding phenol derivatives with Cp^*TiCl₃ in the presence of excessive triethylamine. Under the conditions of low Al/Ti molar ratio (e.g. 500) and high reaction temperatures (≥ 70^οC), all the titanium complexes display higher catalytic activities towards the syndiospecific polymerization of styrene, in the presence of modified methylaluminoxane (MMAO) as a cocatalyst, than their mother complex Cp^*TiCl₃. The catalyst activities and polymer yields as well as polymer properties are considerably affected by the steric and electronical effects of the bidentate ligands.