Cationic palladium complexes with ketophosphine and phosphino enolate ligands and their reactivity towards C-C coupling reactions. Crystal structuresof [PdMe{Ph2PCH2C(O)Ph}-(PCy3)](PF6) and [Pd{Ph2PCH - C(-(O)over-bar)Ph}(SMe2)(2)](PF6)

Two types of monocationic Pd(II) complexes are reported, which contain eith er the functional P,O phosphine ligands Ph2PCH2C(O)Ph or Ph2PCH2C(O)NPh2 or an anionic chelating phosphino enolate. The first set of complexes include s [PdMe{Ph2PCH2C(O)Ph}(PPh3)](PF6) (1), [PdMe{Ph2PCH2C(O)Ph}(PCy3)](PF6) (2 ), [PdMe{Ph2PCH2C(O)NPh2}(PPh3)](PF6) (3), and the second [Pd{Ph2PCH<(...)u nder bar>C(<(...)under bar>(O) over bar)Ph}(SMe2)(2)](PF6) (5), which was o btained by an interesting ligand redistribution reaction between cis-[Pd{Ph 2PCH<(...)under bar>C(<(...)under bar>(O) over bar)Ph}(2)] and [Pd(SMe2)(4) ](PF6)(2). Compounds 1 and 5 display catalytic activity for ethylene dimeri zation. A preliminary study on ethylene/CO copolymerization with complexes 1-3 identified compound 1 as a catalyst precursor. This led to the in situ preparation of an active species for ethylene/CO copolymerization, starting from a Pd(O) precursor and appropriate ligands. The structures of complexe s 2 and 5 have been determined by X-ray diffraction. (C) 2000 Elsevier Scie nce S.A. All rights reserved.