Ethylenedione: An Intrinsically Short-Lived Molecule

Facile crossover to the singlet potential energy surface followed by dissociation into two ground-state CO molecules [Eq. (1)] makes triplet ethylenedione—hitherto regarded as stable—extremely short-lived. Thus ethylenedione has remained undetected up to now not because it is elusive but due to its intrinsic instability, which is confirmed by mass spectrometric studies and theoretical calculations.