Palladium(II)complexes of new OPN phosphine ligands and their application in homogeneously catalysed reactions of CO with alkenes or alkynes

摘要

Palladium complexes of a series of functionalised phosphines bearing the OPN donor set [2-pyCH_2P(Ph)CH_2-(CHOCH_2CH_2CH_2),1;2-py CH_2P(Ph)-CH_2CH_2(CHOCH_2CH_2O),2;2-pyCH_2P(Ph)CH_2CH_2CO_2Me,3;2-pyP(Ph)CH_2(CHOCH_2CH_2-CH_2),4;2-py = 2-pyridyl] have been prepared and characterised.Ligands 1-3 form five membered P-N chelates which is confirmed for PdCl_2 complexes of 1 and 3 by X-ray crystallography.O-coordination appears to be generally disfavoured although there is evidence of transient O-coordination for selected Pd complexes of 4.Palladium methyl and acetate complexes of all four ligands have been tested for catalytic activity in ethene/CO copoly-merisation as well as alkoxy-carbonylation of propyne.Complexes of 1 and 4 show some activity in the copolymerisation reaction and complexes of 4 are active in the methoxy carbonylation of propyne.Unlike related pyridyl(diaryl)phosphines,4 produces a much more stable catalyst system that does not require large excesses of ligand to maintain activity.