OLEFIN ISOMERIZATION CATALYSTS BASED ON DITHIO PALLADIUM(II) COMPLEXES

The catalytic double-bond shift isomerization of alpha-olefins by dithio-beta-diketonate palladium complexes Pd{CH3C(S)CHC(S)CH3}(PL1L2L3)X (1) and [Pd{CH3C(S)CHC(S)CH3}{Ph2PCH2CH2PPh2}]Y (2) (X = I, 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.