Study of Insertion of Olefins and/or Carbon Monoxide into Phosphine−Imine Palladium Methyl Complexes

Abstract

Palladium methyl complexes with a phosphine−imine (P∼N) bidentate ligand, [Pd(P∼N)MeCl] (1), [Pd(P∼N)Me(CH3CN)](BF4) (2), and [Pd(P∼N)Me(PPh3)](BF4) (3), are treated with CO to result in the corresponding Pd−acyl complexes 4−6. NMR studies indicate the formation of a sole isomer with the acyl group cis to the phosphine donor. The neutral complex 4 and the triphenylphosphine-substituted complex 6 cannot serve for the insertion of ethylene. However, the acetonitrile complex 5 appears to be active in the insertion reaction with various alkenes as well as ethylene/CO (E-CO) co-oligomerization, resulting in the products 7−14 and 16, which have been isolated and characterized by spectroscopic methods. X-ray structures of 1, 2, 3, 4, 7, 10, 11, and 13 are revealed.