Structural Aspects of Palladium Systems Used as Catalyst Precursors in CO/olefins co- and ter-Polymerisation Reactions

The synthesis and characterisation of three palladium complexes, involved in the homogeneous catalysis towards the CO-olefins coand ter-polymerisation reactions, are reported. The Pd (dpk·CH3OH) (CF3CO2)2 (1), (dpk = di(2-pyridyl) ketone) and Pd (dppp)(bipy) B(C6F5)4 2 (2), (bipy = 2,2’-bipyridine, dppp = 1,3-bis(diphenylphosphino)propane) compounds are examples of a neutral complex and of a dicationic mixed-ligands one, respectively. The catalytic activity of type 2 complexes was reported to be strongly dependent on the nature of the anion, and the tetra(perfluorophenyl) borate salt represents the best choice to date for the CO/aliphatic olefins copolymerisation. In both structures, the metal has a square planar coordination and the structural aspects of these complexes are discussed in comparison with their catalytic properties. The crystal structure of Pd(bipy)(naphthoquinone) (3), which is a putative intermediate of the catalytic cycle, is also reported.