the phosphate e g a mixture of mono and di isopropylphosphoric acid or di n butyl phosphoric acid is added to form a catalyst precursor this mixture is sonicated to dissolve the resulting hydrated palladium oxide and the excess acetonitrile is stripped off to leave a yellow orange oil this oil may be added to a solution containing the diene polymer or copolymer a second catalyst precursor is formed by complexing palladium with a dialkylidene acetone having the structure iii of a 1 4 pentadiene 3 one derivative str1 wherein r 1 to r 6 may be the same or different and are hydrogen alkyl aryl aralkyl or cycloalkyl suitable alkyl groups include methyl ethyl n propyl isopropyl n butyl isobutyl sec butyl and similar groups aryl groups include phenyl benzo naphthyl indenyl and similar groups useful aralkyl groups include benzyl beta phenethyl etc while cycloalkyl groups include cyclopentyl cyclohexyl cycloheptyl and the like other ligands which contain the pentadiene 3 one structure are derivatives of 4 methylene 2 5 cyclohexadiene 1 one and cyclopentadieneone str2 wherein r 2 r 7 for the 4 methylene 2 5 cyclohexadiene 1 one derivatives and r 2 r 5 for the cylcopentadieneone derivatives may be the same or different and are hydrogen alkyl aryl aralkyl or cycloalkyl groups suitable alkyl groups include methyl ethyl n propyl isopropyl n butyl isobutyl sec butyl and similar groups aryl groups include phenyl benzo.