OLIGOMERIZATION OF ETHYLENE WITH CATIONIC PHENANTHROLINE(METHYL)PALLADIUM COMPLEXES

A number of cationic phenanthroline(methyl)palladium complexes, 3a-e, have been generated in the presence of ethylene. The idea behind this design is twofold: (I) the presence of the phenanthroline ligand shoul d prevent potential beta-hydrogen elimination and (II) the cationic st ate of palladium decreases the stability of the bond between the alken e and the metal and will thereby facilitate migratory insertion of eth ylene into the sigma-carbon-palladium bond. In the absence of steric c onstraints at the phenanthroline ligand, these complexes catalyze the dimerization and oligomerizations of ethylene. General factors conside red of importance for oligo- and poly-merization of alkenes are discus sed.