Abstract: Solid .pi.-allyl complex catalysts comprising:(A) A palladium source;(B) A monotertiary phosphine electron donor ligand;(C) A combination of a reducing agent capable of reducing the palladium source to an oxidation state of less than 2 and a Lewis acid capable of forming a coordination bond with palladium; and(D) An acidic, solid, silica-based support material, are useful in the codimerization of a conjugated diene and a monoene. Preferably, the catalyst is activated by the additional presence of a conjugated diene. In a preferred embodiment, the solid .pi.-allyl palladium complex catalyst prepared from palladium acetylacetonate, triphenylphosphine, diethylaluminum chloride and a calcined silica-alumina support having a separate, distinct alumina phase is useful in the selective codimerization of 1,3-butadiene and ethylene to form trans-1,4-hexadiene.

Abstract: A catalyst composition for the polymerization, including oligomerization and dimerization, of olefins is provided by combining (A) a nickel source, (B) a chlorocontaining electron donor ligand, and (C) a Lewis acidreducing agent, in molar ratios of (B) to (A) of about 0.5 to 15:1 and (C) to (A) of about 3 to 40:1. Preferred catalyst components are nickel acetylacetonate, chlorodiphenylphosphine and ethylaluminum sesquichloride. These catalyst compositions can be supported on a suitable carrier.