Formation of Pentaamminecarbonylruthenium (II) by Electrochemical Reduction of Pentaamminechlororuthenium (III) in Aqueous Formic Acid-Formate Solutions

Abstract

Pentaamminecarbonylruthenium(II) chloride was obtained by the controlled-potential electrolytic reduction of pentaamminechlororuthenium(III) chloride in aqueous formic acidsodium formate solutions. The spectral measurement with an optically transparent thinlayer electrode cell suggested that the reaction preceeded through pentaammineformatoruthenium(II). The kinetics of the reaction was studied polarographically at 25°C in the formate solutions containing chloride ions with the ionic strength of 0.5 mol·dm^-3. The results were explained by postulating a rate-determining step in which pentaammineformatoruthenium(II) in equilibrium with the aqua-and pentaamminechlororuthenium(II) species was converted into the carbonyl complex. The rate-determining step, was found to be accelerated by hydrogen ion and formic acid.