Depolymerization kinetics of Ru4(OH)48+ and characterization of the reaction product: Dimeric Ru(III) ion

Abstract Perchloric acid solutions of Ru 4 (OH) 4 8+ were prepared by the controlled-potential reduction of Ru(IV) at platinum electrodes in a high-speed coulometric cell. The solution spectrum of Ru 4 (OH) 4 8+ is reported. Tetrameric Ru(III) ion decomposes in a reaction which is first-order with respect to its concentration, but independent of the acidity, to another species of the same valence state which is believed to be a dimeric ion (Ru 2 (OH) 2 4+ or similar). Electrochemical reduction of this species yields Ru 2+ which can be reoxidized only to Ru 3+ , the most stable of the Ru(III)-aquo ions.