Syntheses of Ester-Substituted Norbornyl Palladium Complexes Ligated with ^<i>t</i>Bu₃P: Studies on the Insertion of <i>exo</i>- and <i>endo</i>-Monomers in the Ester-Substituted Norbornene Polymerization

Abstract

Exo - and endo -isomers of an ester-substituted norbornene derivative [5-norbornene carboxylic acid methyl ester (NBE)] are compared in the addition polymerization using t Bu 3 P-ligated palladium complex 1 . The polymerization rate of endo -NBE is slower than that of the corresponding exo- NBE. Each of exo - and endo -NBE inserted complexes was synthesized and the insertion rate constant was determined for exo -NBE and endo -NBE. These experiments revealed that the consecutive exo -NBE insertion was faster than the consecutive endo -NBE insertion by 2-fold. On the other hand, in polymerization of an exo- NBE/ endo- NBE (1:1) mixture, consumption rates of exo -NBE and endo -NBE were almost equal and the production rate of the poly-NBE from this mixture was almost the same as that of homopolymerization of exo -NBE.