Mechanisms of complex formation in the reactions of 1,2-dihydroxybenzene and 1,2-dihydroxy-4-methylbenzene with palladium(II) chloride and with aquapalladium(II), equilibria and kinetics in acid media

Abstract

Palladium(II) chloride and aquapalladium(II) ions react rapidly with benzene-1,2 diols (1,2-dihydroxybenzene and 1,2-dihydroxy-4-methylbenzene) to form a green 1 : 1 complex. The reactions are reversed by addition of an excess of acid. Values of equilibrium constants for the overall reactions have been determined both from measurements on the equilibrium mixtures and from kinetic parameters. The green product is considered to be a chelate complex of Pd^o and an o-quinone and the mechanisms are discussed in terms of a general scheme that takes into account possible intermediate species.