These results suggest that that Ru(NH3)6 3+/2+ -mediated reduction of S2O8 2-by CO2 • -, path B (eq 24 followed by eq 18) is the dominant path in the autocatalytic mechanism. This finding, based on analysis of the CV data, is consistent with the rate constant for the reduction of Ru(NH3)6 3+ by CO2 • -(i.e., the first step of path B, kf 24 > 10 7 M -1 s -1 , Table ), being at least two orders of magnitude larger than the rate constant for the reduction of S2O8 2-by CO2 • -, kf (1 x 10 5 M -1 s -1 ).