HEPTANE-SOLUBLE HOMOGENEOUS ZIRCONOCENE CATALYST - SYNTHESIS OF A SINGLE DIASTEREOMER, POLYMERIZATION CATALYSIS, AND EFFECT OF SILICA SUPPORTS

Bis(1-indenyl)-di[(1'S, 2'R, 5'S)-menthoxy]silane (1) was converted into a mixture of corresponding ansa-diastereomeric zirconocenes. Further purification afforded a single diastereomer, di[(1'S, 2'R, 5'S)-menthoxy]silylene-bis[eta(5)-1(R, R)-(+)-indenyl]dichlorozirconium (2), which is optically active and hydrocarbon soluble. Extremely rapid ethylene, propylene, and ethylene-hexene polymerizations were observed both in toluene and n-heptane solutions; for instance, at 50 degrees C, activity for ethylene polymerization reaches similar to 1.5 X 10(10) (g of PE/((mol of Zr).[C2H4]. h). The ''bare'' zirconocenium ion generated from 2/TIBA/Ph(3)CB(C6F5)4 exhibits unusual polymerization behaviors; the polymerization activity increases monotonically with temperature of polymerization (T-p) up to a conventional polymerization condition (50-70 degrees C), and the C-13 NMR study shows that the isotactic polypropylene obtained has fairly high [mmmm] methyl pentad distributions at high T-p(> 25 degrees C with [mmmm] similar to 0.93-0.75) and a perfect stereoregularity at low T-p(less than or equal to 0 degrees C with [mmmm] > 0.99). The catalyst precursors 2 and Et(Ind)(2)ZrCl2, (3) supported on silica by different approaches produced poly(olefins) of different molecular weights and stereoregularities, and a methylaluminokane and Ph(3)CB(C6F5)(4) free silica-supported zirconocene system was found to be activated by triisobutylaluminum. (C) 1995 John Wiley and Sons, Inc.