Oligomerization and isomerization of olefins by catalysts derived from nickel complexes of dithio-β-diketonates

The complexes [Ni{R1C(S)CR2C(S)R3}2]1 and [Ni{R1C(S)CR2C(S)R3}(PL1L2L3)X]2(R, L = alkyl, aryl or CF3; X = Cl, Br or I) have been prepared. The complexes 2 can be chemically anchored to polystyrene or silica–alumina supports via pendant phosphine ligands to form the derivatives 3. The species 2 and 3 in combination with a suitable co-catalyst form extremely active catalysts for the oligomerization of ethylene, propylene or butenes. The immobilised systems show no significant signs of leaching after 24 h operation. In general the oligomerization is highly selective to dimers, however, selectivity and catalyst activity are markedly affected by changes in L. Changes in R affect catalyst activity only.