Reactions between microhydrated superoxide anions and formic acidElectronic supplementary information (ESI) available: The ESI contains additional data and discussion regarding double collisions, occurrences of isobaric overlap in recorded mass spectra, as well as structural and energetic data from the quantum chemical computations and a kinetic analysis of the energy profile given in Fig. 3. See DOI: 10.1039/c7cp03820h

Reactions between water clusters containing the superoxide anion, O 2 &z.rad; − (H 2 O) n ( n = 0-4), and formic acid, HCO 2 H, were studied experimentally in vacuo and modelled using quantum chemical methods. Encounters between microhydrated superoxide and formic acid were found to result in a number of different reactions, including (a) proton transfer, (b) ligand exchange, (c) H 2 -elimination (affording microhydrated CO 4 &z.rad; − ), and (d) dihydrogen transfer (affording H 2 O 2 and microhydrated CO 2 &z.rad; − ). The effect of reactant-ion hydration on reaction rates was investigated and the involved reaction mechanisms were elucidated. Reactions between water clusters containing the superoxide anion, O 2 &z.rad; − (H 2 O) n ( n = 0-4), and formic acid, HCO 2 H, were studied experimentally in vacuo and modelled using quantum chemical methods.