Incipient wetness method for making metal-containing cyanide catalysts

This invention relates to certain metal-containing catalysts and to methods for preparing metal-containing catalysts for alkylene oxide polymerization. Metal cyanide catalysts are prepared by first forming a precipitate using no more than a stoichiometric amount of a water-soluble metal salt of the form MA, based on the amount of metal cyanide compound that is used. The precipitate is then treated with an additional quantity of a metal salt of the form MA, in which Mmay be the same as or different than M. The catalyst is treated with a complexing agent, either during the precipitation step or during the subsequent treatment with the MAsalt.