Quantum chemical studies on peroxodisulfuric acid–sulfuric acid–water clusters

We have applied a multistep quantum chemistry method to study the formation energetics and binding patterns of sulfuric acid–peroxodisulfuric acid–water clusters, with special focus on the O–O bridge. The length of the O–O bridge correlates linearly with the average length of S–O bonds next to it. The clustering of peroxodisulfuric acid with sulfuric acid and water is thermodynamically favorable, as is the replacement by peroxodisulfuric acid of one (but only one) of the sulfuric acid molecules in a sulfuric acid–water cluster. However, the presence of H2S2O8 does not enhance the addition of sulfuric acid to the clusters.