The mechanism of hydroxypalladation in acyclic and cyclic η 2 -diene complexes

Abstract

Cyclic dienes in aqueous acetone mixtures do not reduce palladium(II) complexes to palladium as readily as do acyclic ones. It is suggested that the difference arises because of conformational effects in the (η 2 -diene)palladium(II) complexes, that nucleophilic attack on the coordinated CC bond by H 2O (or OH −) is intermolecular, and that this process only occurs when this bond is nearly perpendicular to the X—Pd—X axis (where the ligands X are cis to the CC group).