Palladium-Catalyzed Ethylene/Methyl Acrylate Cooligomerization: Effect of a New Nonsymmetric α-Diimine

Article abstract of DOI:10.1002/cctc.201200520

A new nonsymmetric bis(aryl-imino)acenaphthene (Ar-BIAN) ligand, featured by a subtle steric and electronic unbalance of the N-donor atoms, is reported. With the new ligand and the corresponding symmetrically substituted derivatives, both neutral and monocationic Pd-CH₃ compounds have been synthesized and characterized. The series of the monocationic complexes [Pd(CH₃)(L)(Ar-BIAN)][PF₆] (L=CH₃CN, dmso) has been extended to dimethyl sulfoxide derivatives. The monocationic complexes are tested as precatalysts for the ethylene/methyl acrylate cooligomerization under mild reaction conditions of temperature and ethylene pressure. The catalytic product is a mixture of ethylene/acrylate cooligomers and higher alkenes. The catalysts containing the new nonsymmetric ligand are found to be more productive than those with the symmetric Ar-BIANs. The Pd-dmso catalysts are more productive and show a longer lifetime than their Pd-NCCH₃ counterparts.