Synthesis and structure of Pd(II) complexes containing chelating (phosphinomethyl)oxazoline P,N-type ligands; copolymerisation of ethylene/CO

The ligands (2-oxazoline-2-ylmethyl)diphenylphosphine (III or PCH(2)ox) and (2-oxazoline-2-ylmethyl-4,4-dimethyl)diphenylphosphine (IV or PCH(2)ox(Me2)) have been used as chelates towards Pd(II) methyl complexes. The complexes [PdMe(Cl)(PCH(2)ox)] 2a and [PdMe(Cl)(PCH(2)ox(Me2))] 2b were obtained from [PdMe(Cl)(cod)] (cod = cycloocta-1,5-diene) in 83% and 94% yield, respectively, and compared to [PdCl2(PCH(2)ox(Me2))] 1 which was characterised by X-ray diffraction. A series of cationic methyl complexes obtained by chloride abstraction in the presence of MeCN, SMe2, P(OPh)(3) or no added donor except the counter ion were prepared in order to evaluate their catalytic performances in ethylene/CO copolymerisation.