The reaction of hydroxo-species of palladium(II) with bidentate nucleophiles

Abstract

The species present in solutions of [Pd(bipy)(H₂O)₂]²⁺(bipy = 2,2′-bipyridine) and [Pd(en)(H₂O)₂]²⁺ in the [OH^–] range 0.01–0.1 mol dm^–3 react with the nucleophiles (L–L) ethylenediamine (en), NNN′N′-tetramethylethylenediamine, or glycylglycinate to give respectively [Pd(L–L)₂]ⁿ⁺(n= 0 or 2) and [Pd(en)(L–L)]ⁿ⁺(n= 1 or 2). The K_obs. values for the entry of the first L–L, which occurs in one observable step, depend both on [L–L] and [OH^–] and the observed rate law, under pseudo-first-order conditions, is K_obs.={a+b/[OH^–]}[L–L]. The kinetic data have been interpreted assuming that both a monohydroxo- and a dihydroxo-complex, in fast equilibrium, are the reacting species. The reactivity of the dihydroxo-complex could be evaluated only in the case of the bipy species.