V vs Ag/AgCl (Figure ). The hydrogen bonding with explicit solvation preferentially stabilizes the more anionic reactant C2O4 2-compared to the less anionic product C2O4 •-, thus increasing the magnitude of the electron removal energy, pushing the potential to a more positive value. With these improved energetics, Marcus theory gives a shallow free energy barrier of ∆𝐺 ǂ = 4 𝑘𝐽/mol for the oxidation of the solvated C2O4 2-species by the highly oxidizing SO4 Upon oxidation, the C-C bond in C2O4 •-undergoes an elongation of about 0.25-0.30 Å (Figure ). Periodic AIMD simulations show similar changes in the bond length upon oxidation, with an average bond elongation of 0.33 Å (see SI for details). This is significantly shorter than the 1 Å increase in the O-O bond that occurs upon reduction of S2O8 2-to S2O8 3-• that we reported previously. The inner-sphere reorganization energy (λ i ) for C2O4 2-oxidation at λ i = 81 kJ/mol is significantly lower than the reorganization energy for S2O8 elongation, together with the generation of a Lewis acid-base pair (CO2 and CO2 •-) in C2O4 •- (Figure ), can lead to a significantly longer lifetime of C2O4 •-as compared to S2O8 , where no such Lewis acid-base pair is obtained (SO4 •-and SO4 2-). This observation is consistent with the numerical simulations presented later and is further supported by the results for the AIMD simulations of these four solvated species (S2O8 2-, S2O8 3-• , C2O4 2-, and C2O4 •-) in the aqueous phase (Figure ), which show that C2O4 •-is more stable than S2O8 3-• over the period of our simulations.