HOMOGENEOUS CATALYSIS OF D2–H2O EXCHANGE BY RUTHENIUM (III) CHLORIDE: EVIDENCE FOR THE HETEROLYTIC SPLITTING OF HYDROGEN

Abstract

The prediction, based on earlier studies of the ruthenium(III) chloride catalyzed oxidation of H2 by iron(III), that in the absence of iron(III) or other oxidants ruthenium(III) chloride should catalyze homogeneously the isotopic exchange between D2 and H2O has been confirmed. A kinetic study was made of this exchange reaction in which the dependence of the exchange rate and of the exchange product distribution (HD:H2 ratio) on the concentrations of ruthenium(III), hydrogen ion, and chloride ion were determined. The results, and in particular the observation that the HD:H2 ratio of the exchange product increases with the concentrations cf H+ and Cl−, support the view that the ruthenium (III)-catalyzed oxidation of D2 by iron(III) and the D2–H2O exchange reaction proceed through related mechanisms involving a common rate-determining step in which D2 is split heterolytically and a deuteridoruthenium(III) complex is formed.