SIMBAD references

Three proposed mechanisms of cyclopropenone (c-H₂C₃O) formation from neutral species are studied using high-level electronic structure methods in combination with nonadiabatic transition state and collision theories to deduce the likelihood of each reaction mechanism under interstellar conditions. The spin-forbidden reaction involving the singlet electronic state of cyclopenylidene (c-C₃H₂) and the triplet state of atomic oxygen is studied using nonadiabatic transition state theory to predict the rate constant for c-H₂C₃ O formation. The spin-allowed reactions of c-C₃H₂with molecular oxygen and acetylene with carbon monoxide were also investigated. The reaction involving the ground electronic states of acetylene and carbon monoxide has a very large reaction barrier and is unlikely to contribute to c-H₂C₃O formation in interstellar medium. The spin-forbidden reaction of c-C₃H₂with atomic oxygen, despite the high probability of nonadiabatic transition between the triplet and singlet states, was found to have a very small rate constant due to the presence of a small (3.8 kcal/mol) reaction barrier. In contrast, the spin-allowed reaction between c-C₃H₂ and molecular oxygen is found to be barrierless, and therefore can be an important path to the formation of c-H₂C₃O molecule in interstellar environment.