Palladium complexes of 2-pyridin-2-yl substituted 1,3-bis(diphenylphosphino)propane: Highly active catalysts for the room-temperature copolymerization of carbon monoxide with ethene

The 2,2'-disubstituted 1,3-bis(diphenylphosphino)propane derivatives [XC(Me)(CH 2 PPh 2 ) 2 ] (X = 2-py, la; X = CH 2 OMe, 1b; X = Ph, 1c) and their corresponding palladium complexes [(P-P)PdCl 2 ] (2a-c), [(P-P)Pd(OAc) 2 ] (3a-c), [{2-methyl-2-pyridin-2-yl-1,3-bis(diphenyl-phosphino)propane}PdClMel](4a), and [{(S)-(+)-N,N-dimethyl-α-methylbenzylamine-C,N}-Pd{2-MeOCH 2 CMe(CH 2 PPh 2 ) 2 }][ClO 4 ] (5b) have been prepared and characterized. Palladium(II) complexes of 2-methyl-2-pyridin-2-yl-1,3-bis(diphenylphosphino)propane (la) are highly active for the room-temperature copolymerization of ethene and carbon monoxide and, under our conditions, markedly more active than systems based on 1,3-bis(diphenyl-phosphino)propane (dppp), 1b and 1c. Catalysts formed from dppp, 1b, and 1c all show the expected increase in activity at elevated temperature (90 °C), while that formed from la is highly temperature-sensitive and rapidly decomposes.