Novel polymer-supported β-dithioketonate nickel catalysts for selective propylene dimerization

Brominated and chloromethylated styrene-divinylbenzene resins were used for the synthesis of polymer-bound dithio-b-diketones, obtained by anchoring the chelate ligand through the central position. The heterogenized dithio-b-diketone ligand was subsequently reacted either as sodium salt with a Ni(II) phosphino derivative or directly with a Ni(0) complex in the presence of a free phosphine and activated in situ with an aluminum co-catalyst for the selective dimerization of propylene to 2,3-dimethylbutenes. The heterogenized catalysts so obtained showed, particulary when prepared starting from chloromethylated styrene/divinylbenzene resins,very high activity and selectivity towards 2,3-dimethylbutenes, Moreover, the above catalysts, at least under the adopted reaction conditions, did not display any appreciable metal leaching during the catalytic cycle, thus working as really heterogeneous systems. Copyright (C) 1999 John Wiley & Sons, Ltd.