The covalently bound radical anion [O2C-CO](-.) is formed when 1,3-dioxolane-2,5-dione captures an electron followed by retro-cleavage of CH2O. Calculations at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G(d) level of theory indicate that there are a number of neutral isomers with formula C2O3, ViZ- van der Waals complex O2C - - - CO (rel. energy = 0 kcal mol(-1)), singlet oxiran dione (+60.9 kcal mol(-1)), triplet OCOCO (+99.4 kcal mol(-1)), covalently bound triplet O2C-CO (+ 107.6 kcal mol(-1)), singlet trioxapropellane (+171.9 kcal mol-1) and triplet trioxapropellane (+ 222.4 kcal mol(-1)). Of these, only triplet O2C-CO is accessible by vertical Franck-Condon one-electron oxidation of [O2C-CO](-.). Neutralization reionization experiments of [O2C-CO](-.) (both -NR+ and -NR-) fail to produce recovery signals corresponding to ionized C2O3, which means that if neutral C2O3 is stable, the lifetime must be < 10(-6) sec. The -NR+ spectrum of [O2C-CO](-.) shows peaks corresponding to CO+. CO2+. and to [O dropC dropC dropO](+.). The last of these species can only be formed from a decomposing C2O3+. radical cation by a process endothermic by 47 kcal mol(-1) [at the CCSD(T)/aug-cc-pVDZ//B3LYP/6-31G(d) level of theory]. Calculations at this same level of theory indicate that the vertical one-electron oxidation of [O2C-CO](-.) to triplet O2C-CO ground state produces the neutral with essentially no excess energy. There are two dissociation pathways of this triplet neutral, (i) an endothermic process yielding (CO)-C-3 + (CO2)-C-1 (+ 28.9 kcal mol(-1)), and (ii) an exothermic process (-6.8 kcal mol(-1)) with a barrier of 5.4 kcal mol(-1) yielding (CO)-C-1 + (CO2)-C-3. A combination of experimental and theoretical data, suggests that vertical oxidation of [O2C-CO](-.) produces only one neutral C2O3 isomer; a transient triplet O2C-CO neutral whose lifetime is less than 10(-6) sec.