Studies of radicals in oxalate systems

Abstract

We have studied a γ-irradiated single crystal of potassium hydrogen oxalate (KHC2O4) using E.S.R. at room temperature. Spin hamiltonian parameters were determined for two of the radicals. One of these, which decayed within 24 hours, was assigned to CO- 2. This radical was associated with C2O2O4 in the crystal structure. The arguments for this assignment were based on the relation between the directions observed for the 13C hyperfine tensor and the crystal structure, together with the interaction of CO- 2 with the hydrogen bonded proton. The second radical was found to be stable and interacted with mainly two protons. One of these had α-proton character and the other, with smaller coupling, behaved like a ĊOH kind of proton. This radical was identified as OOC-ĊHOH, for the results could be understood if one of the oxygens, of the oxalate ion is replaced by a proton.