Energy-resolved collision-induced dissociation of peroxyformate anion: enthalpies of formation of peroxyformic acid and peroxyformyl radical.

We measure the oxygen-oxygen bond dissociation energy of the peroxyformate anion (HCO(3)(-)) using energy-resolved collision-induced dissociation with a guided ion beam tandem mass spectrometer. The analysis of the dissociation process from HCO(3)(-) ((1)A') to HCO(2)(-) ((1)A(2)) + O((3)P) requires consideration of the singlet-triplet crossing along the reaction path and of the competing OH(-) and O(2)H(-) product channels. The measured oxygen-oxygen bond dissociation energy is D(0)(HCO(2)(-)-O) = 1.30 ± 0.13 eV (126 ± 12 kJ/mol). This threshold energy measurement is used in thermochemical cycles to derive the enthalpies of formation for peroxyformic acid, Δ(f)H(0)(HCO(3)H) = -287 ± 19 kJ/mol, and peroxyformyl radical, Δ(f)H(0)(HCO(3)(•)) = -98 ± 12 kJ/mol. These values are in good agreement with computational energies.