A new set of allyl-functionalized cyclopentadienyl (Cp') lanthanocenes were synthesized and characterized by MS, IR and EA. A structure in which the lanthanide metal is a nine-coordinate center solvated by two THF molecules was proposed. No evidence of intramolecular coordination of the alkenyl C=C to the central metal was observed. Single component bulk polymerization of MMA catalyzed by Cp' yttrocene indicated that at the optimum condition of 40degreesC and MMA/catalyst molar ratio of 400:1 a predominantly syndiotactic (rr > 70%) polymer with M-n > 500,000 and molecular weight distribution (M-w/M-n) < 1.4 is obtained. The effects of variation in temperature, time of polymerization and initiator concentration was also studied. The title catalysts showed moderate activity for MMA/catalyst molar ratio of up to 1200:1. At a molar ratio of 800:1 a polymer M-n = 1.6 x 10(6) was obtained. The electron donating influence of the functional group on catalyst activity was discussed. The effects of co-catalysts on the polymerization were also studied. (C) 2002 Elsevier Science B.V. All rights reserved.