ansa-Indenylamidodimethyltitanium complex ([t-BuNSiMe(2)Ind]TiMe2:1) was synthesized by one-pot reactions starting from the ligand, MeLi and TiCl4. The structure of 1 was determined by X-ray crystallography and the results obtained revealed that the indenyl ligand coordinate to titanium in an eta(4)-tendency. Propylene polymerization was conducted with I in toluene or heptane as solvent at 0 degrees C in the presence of dried methylaluminoxane (MAO) or dried modified MAO (MMAO), which was prepared from the toluene solutions of MAO or MMAO by removing free trialkylaluminium contained. Polymerization behavior was investigated from the consumption rate of propylene in a semi-batch system. The dried MAO/toluene system showed the highest activity without any deactivation. The produced polymer in the dried MAO/toluene system had the highest molecular weight and narrowest molecular weight distribution. The number-average molecular weight of the polymer increased almost linearly with increasimg polymerization time accompanied by narrowing molecular weight distribution from 1.42 to 1.37 and the number of polymer chains was almost constant. Thus, it was found that quasi-living polymerization of propylene proceeded. The C-13 NMR measurement indicated that 1-dried MAO/toluene produced poly(propylene) with isotactic triad of 40%. (c) 2005 Elsevier B.V. All rights reserved.