Ab initio investigation of the CO4 and CO2N2 molecules as possible high-energy metastable species

A possibility of the CO4 molecule existence is studied theoretically at the SCF, MP2, MP4, and CISD levels of theory using the 6-31G* basis set. It is shown that there exist at least two local minima on the potential energy surface (PES) of the lowest singlet state of this molecule, corresponding to its D-2d and C-2v, isomers. Both isomers are predicted to be vibrationally stable, but metastable (by 80 kcal mol(-1) and 48 kcal mol(-1) respectively) relative to the lowest dissociation asymptote CO2(X(1) Delta Sigma(g)(+))+O-2(a(1) Delta(g)). The possible channels of decay and some possible ways of production of both CO4 isomers are considered. The results obtained make it possible to hope that the CO4 molecule may exist (at least at low temperatures) and may be of interest both as a possible source of the singlet oxygen O-2(a(1) Delta(g)) and as an energy carrier. Based on the results of ab initio calculations performed, the existence of the local metastable minimum on the PES of the CO2N2 molecule, corresponding to its structural form O-2 = C = N-2, is predicted. It is shown that the adiabatic decay of this structure must be accompanied by the release of about 190 kcal mol(-1) of heat.