Cationic palladium(II)–acetylacetonate complexes containing phosphine and aminophosphine ligands and their catalytic activities in telomerization of 1,3-butadiene with methanol

Abstract The Pd(II) complexes [Pd(acac)(L)n]BF4 were synthesized by the reaction of [Pd(acac)(MeCN)2]BF4 with L (n = 2: L = PCyPh2, PCy2Ph, P(NMe2)3, P(NEt2)3, tri-2-furylphosphine, tri-2-thienylphosphine; n = 1: L = 2 dicyclohexylphosphino-2′,6′-dimethoxybiphenyl, 2-dicyclohexylphosphino-2′,4′,6′-triisopropylbiphenyl). The structural features of the complexes were analyzed by NMR and FTIR spectroscopies. Complexes [Pd(acac)(PCyPh2)2]BF4 and [Pd(acac)(PCy2Ph)2]BF4 were characterized by X-ray diffractometry. The cationic palladium catalyst precursors were found to be active catalysts for telomerization of 1,3- butadiene with methanol under base-free conditions. Complexes [(acac)Pd(PCy2Ph)2]BF4 and [(acac)Pd(TOMPP)2]BF4 in terms of yield, selectivity, and stability are effective for the catalytic telomerization (TOMPP = tris(2-methoxyphenyl)phosphine). Using 0.001–0.0025 mol% palladium loading methoxy-2,7-octadienes were obtained with chemoselectivities of 76–94% and TON up to 60000 mol 1,3-butadiene per mol Pd.