Steady-state and pulse radiolysis of some palladium(II) complexes

Abstract

Steady-state and pulse radiolysis studies of three complementary palladium(II) complexes, [Pd(bipy)Cl₂]. [Pd(bipy)(HypO)]Cl and [Pd(HypO)₂](bipy = 2,2′-bipyridine, HypO = 4-hydroxy-L-prolinate) have been performed. The site of attack of e^–(aq) and OH˙ radical in these complexes and the effect of γ irradiation on the optical activity of the complexes containing HypO has been assessed using optical absorption and circular dichroism techniques. The steady-state γ irradiation results for [Pd(bipy)Cl₂] and [Pd(bipy)(HypO)]⁺ are significantly different from those of [Pd(HypO)₂] with both e^–(aq) and OH˙. Precipitation of fine metal palladium particles is observed in the reaction of e^–(aq) with [Pd(HypO)₂]. Formation of a new optically active species is observed in the reaction of OH˙ with both [Pd(HypO)₂] and [Pd(bipy)(HypO)]⁺ accompanied by a substantial loss in optical activity of the parent complexes. The substitution of one amino acid ligand in [Pd(HypO)₂] with bipy leads to a change in the site of attack of e^–(aq) from the metal centre in the binary complex to the bipy ring in the ternary complex. The pulse-radiolysis results support inferences drawn from the steady-state γ-radiolysis investigations.