Catalytic activity of allyl-, azaallyl- and diaza-pentadienyllanthanide complexes for polymerization of methyl methacrylate

A variety of allylic, aza-allylic and 1,5-diazapentadienyllanthanide compou nds were synthesized and their polymerization catalysis toward methyl metha crylate were examined. Divalent Sm[1,3-bis(trimethylsilyl)propenyl](2)(THF) (2) 1 and Sm(1,3-diphenylpropenyl)(2)(THF)(2) 2 were synthesized by the rea ction of potassium 1,3-bis(trimethylsilyl)propenide or potassium 1,3-diphen yl-propenide with SmI2. The aza-allyllanthanide compound was synthesized by the reaction of 2-pyridylbenzyllithium with SmCl3 followed by the reaction with LiCH(SiMe3)(2) to give (2-pyridylbenzyl)(2)SmCH(SiMe3)(2) 3. 1,5-Diaz apentadienyllanthanide was prepared by the reaction of K[(C5H4N)(2)CPh] wit h YbBr2 to give Yb[(C5H4N)(2)CPh](2)(THF)(2) 4, which crystalizes monoclini c, space group C2/C (No. 15), with a = 35.19(1), b = 13.613(3), c = 26.552( 7) Angstrom, beta = 133.77(1)degrees and Z = 8. Preparations of divalent sa marium and ytterbium complexes with bis(2-pyridylphenylmethyl)dimethylsilan e ligand (6 and 7) were carried out by the reaction of dipotassium salt of bis(2-pyridylphenylmethyl)dimethylsilane with SmI2 or YbBr2. By using the r esulting compounds 1, 2, 3, 4, 6 and 7 as initiator, we have examined their catalytic activities for the polymerization of methyl methacrylate and fou nd that compounds 6 and 7 are effective to give high molecular weight isota ctic polymers. (C) 1999 Elsevier Science S.A. All rights reserved.