wherein Q is a member of the group consisting of zinc chloride, zinc iodide, zinc bromide, zinc hydroxy chloride, zinc hydroxy iodide, zinc hydroxy bromide, zirconyl chloride, and zirconyl hydroxy chloride; A is an anion selected from the group consisting of chloride, bromide and iodide; R is the coordinating moiety of a polyhydroxy compound having at least two carbon atoms to which are attached