Highly efficient monocationic palladacycles of chelating diphosphines in C2H4/CO copolymerization

Abstract

Cationic palladacycles of the general formula [{o-C6H4(CH2)N(R)2Pd(P̌P)}][X] (P̌P = Ph2P(CH2)3PPh2, (PhCH2)2C(CH2PPh2)2; X = Cl, PF6) B(C6H5)4; R = H, CH3, CH2C6H5) and [{o-(CH2)C6H4P(o-Tol) 2Pd(P̌P)}][X] (P̌P = Ph2P(CH2)3PPh2; X = Cl, PF6) have been prepared and structurally characterized in the former case (X-ray structure analysis for X = PF6, R = CH3). They are resistant to air and moisture, both in solution and the solid state, and represent one of the most active single-component catalyst systems for the perfectly alternating C2H4/CO copolymerization in aprotic solvents. Stoichiometric model reactions provide insight into the mechanism, suggesting that insertion of carbon monoxide into the carbon-palladium(II) bond initiates the catalytic cycle. Show more