Preparation of (chloromethyl)palladium(II) derivatives from complexes of palladium dichloride by reaction with diazomethane or bis(chloromethyl)mercury

Abstract

Treatment, with diazomethane, of a range of palladium dichloride and dibromide complexes containing chelating ligands has been examined. With all but one, the formation of a mono(halogenomethyl) product was observed. The methylene insertion products from complexes of palladium dichloride are relatively stable if at least one olefin or phosphine ligand is present, but with bis-amine or -sulphide ligands the insertion products could not be isolated. However, all of the insertion products showed at least some tendency to revert to the starting dichloro complexes by loss of the methylene moiety. Products of insertion into a Pd–Br bond are less readily formed than those of the corresponding chloride and the resulting bromomethyl derivatives are less stable than their chloromethyl analogues. Chloromethyl derivatives were also prepared from the dichloride by treatment with bis(chloromethyl)mercury (only one of the two chloromethyl groups is transferred) or from a preformed chloromethyl complex by ligand exchange.