Cationic methyl-palladium(II) complexes containing bidentate N ^ O and P ^ O ligands and a tridentate P ^ O ^ N ligand: Synthesis, carbonylation and catalytic applications in the copolymerisation of carbon monoxide and ethene

Article abstract of DOI:10.1016/S0022-328X(96)06841-6

Cationic methyl-palladium complexes, containing chelating N-O, P-O and P-O-N ligands, of the type {[PdMe(Y-O)L]BF₄} and {[PdMe(P-O-N)]BF₄} [Y-O = methylpicolinate, L = PPh₃, Ph₂PCH₂COOEt; Y-O = Ph₂PCH₂COOEt, L = PPh₃, 2,6-lutidine; P-O-N = diphenylphosphine-acetic acid-methyl-2-pyridylester (Ph₂PCH₂CO₂CH₂(NC₅H₄-2))] have been synthesized. The crystal structure of the complex {[PdMe(N-O)PPh₃]BF₄} indicates distorted square-planar coordination around the palladium centre. The bite angle of the methylpicolinate ligand is small [74.8(4)°] and the Pd-N [2.141(9)A] and Pd-O [2.180(7) A] bonds to the ligand are somewhat elongated. The complexes react readily with CO to give the corresponding acyl complexes, and with the exception of {[PdMe(N-O)Ph₂PCH₂COOEt]BF₄} catalyse the reaction between CO and ethene at room temperature to give polyketone.