A NOVEL PHENOLATE CONSTRAINED GEOMETRY CATALYST SYSTEM - EFFICIENT SYNTHESIS, STRUCTURAL CHARACTERIZATION AND ALPHA-OLEFIN POLYMERIZATION CATALYSIS

This paper reports the convenient ''one-pot'' synthesis of a bifunctio nal -Me4Cp over arc phenolate(-) ligand and the efficient ''one-step'' synthesis of the corresponding Ti-IV and Zr-IV complexes. The reactio n of 2-bromo-4-methylphenol with 2 equiv of (BuLi)-Bu-n followed by ad dition of 2,3,4,5-tetramethyl-2-cyclopentenone produces the bifunction al mono-Cp phenol ligand precursor 2-(tetramethylcyclopentadienyl)-4-m ethylphenol ((TCP)H-2, 1). Reaction of 1 with Ti(CH2Ph)(4) at 60 degre es C in toluene cleanly generates (TCP)Ti(CH2Ph)(2) (2), while the cor responding reaction with Zr(CH2Ph)(4) at higher temperatures affords t he chelated C-2-symmetric zirconocene (TCP)(2)Zr (3). In solution at r oom temperature, the two benzyl groups of 2 are magnetically equivalen t, however, in the solid state, X-ray diffraction reveals that one ben zyl group is coordinated in a normal eta(1)-fashion and the other in a n eta(2)-mode. The small Cp(centroid)-Ti-O angle of 107.7(2)degrees in 2 indicates sterically open features in common with amido-based ''con strained geometry'' polymerization catalysts. Low-temperature NMR-scal e reactions of 2 with B(C6F5)(3) and Ph3C+B(C6F5)(4)(-) indicate the f ormation of the corresponding cationic complexes (TCP)TiCH2Ph+ PhCH2B( C6F5)(3)(-) (4) and (TCP)TiCH2Ph+B(C6F5)(4)(-) (5). Upon activation wi th Ph3C+B(C6F5)(4)(-), complex 2 is highly active for ethylene, propyl ene, and styrene polymerization.