Syn- and anti-(1-Alkyl-π-Allyl)palladium chlorides

Abstract

π-Allylpalladium chlorides with bulky substituents on the terminal carbon atoms are often formed with these substituents in the less stable anti configuration. The activation energy of the π-σ-π rearrangement to the syn configuration increases with the bulkiness of the substituent. The difference in energy between the anti and syn configurations decreases with increasing size of the substituents on the terminal and meso carbon atoms. The phenomena can best be explained by assuming that there is steric interaction between the substituents on the terminal carbons of the π-allyl ligand and either other ligands on the metal or the substituent on the mso carbon of the π-allyl ligand.