Stability and Dissociation of Ethylenedione (OCCO)

This work examines the electronic structure and apparent instability of ethylenedione (OCCO), including an analysis of the singlet and triplet potential energy surfaces along the bending vibrations. While the singlet state is inherently unstable due to the Renner-Teller effect, theory predicts the triplet state to have a stable minimum on the potential energy surface. The stability of the triplet state is examined in detail, taking into account spin-orbit interactions. Using multireference quantum chemical methods, the lifetime of the triplet state is estimated to be in the picosecond range, significantly lower than previously computed. A quasi-atomic molecular orbital (QUAO) analysis is also used to elucidate the nature of bonding along the potential energy surface in both the singlet and triplet states. These calculations confirm the transient nature of the OCCO molecule, although they do not fully explain the lack of experimental detection via spectroscopy, which is known have the capability to probe even shorter lifetimes.