Olefin Isomerization Catalysts Based on Dithio Palladium(II) Complexes

Abstract

The catalytic double-bond shift isomerization of α-olefins by dithio-β-diketonate palladium complexes Pd{CH₃C(S)CHC(S)CH₃}(PL¹L²L³)X(1) and [Pd{CH₃C(S)CHC(S)CH₃}{Ph₂PCH₂CH₂PPh₂}]Y(2)(X = 1, Br; Y = halide, PF₆, BPh₄) is described. Catalysts are formed on activation of the complexes by a variety of alkylaluminium cocatalysts . Several of the catalysts are highly active for isomerization of oct-1-ene and but-1-ene, activities being higher than normally obtained for palladium systems. In contrast to the majority of palladium-based catalysts product distributions rapidly approached thermodynamic equilibrium, with a strong preference for trans products at each stage of the reaction. Products from the isomerization of oct-1-ene were analysed by g.l.c.-F.t.i.r . in conjunction with Kovats retention indices.