Catalytic preparation of polyketone from carbon monoxide and olefin

In a process for the preparation of a polyketone by contacting a mixture of CO and an alkenically unsaturated hydrocarbon with a catalyst the improvement which comprises contacting the CO and the alkenically unsaturated hydrocarbon in the presence of a catalyst comprising a Group VIII metal complex containing bidentate ligands, the Group VIII metal selected from the group consisting of palladium, cobalt, and nickel, the ligands comprising hydrocarbon groups bonded to a Group Va element selected from the group consisting of phosphorus, arsenic, and antimony, wherein the catalyst is a complex compound that is obtained by reacting (1) a palladium, cobalt or nickel compound, (2) a bidentate ligand of the general formula ##STR17## in which M is a Group Va element selected from the group consisting of phosphorus, arsenic, and antimony, R.sup.1, R.sup.2, R.sup.3, and R.sup.4 are identical or different hydrocarbon groups, R represents a divalent organic bridging group having at least two carbon atoms in the bridge, wherein the carbon atoms of the bridging group R do not contain substituents that would sterically hinder formation of the complex compound, and (3) an anion of an acid with a pKa of less than 2, provided said acid is neither a hydrohalogenic acid nor carboxylic acid.