Chemiluminescence of 1,2-Dioxetanone Studied by a Closed-Shell DFT Approach

The chemiluminescence of simple 1,2-dioxetanone has already been studied by both multiconfigurational and density functional theory calculations. The former approach revealed a step-wise biradical mechanism for its decomposition, whereas the latter revealed a concerted mechanism. The first approach was not in line with both computational and experimental findings, whereas the second mechanism was. Due to these apparent mechanistic contradictions and some concerns regarding our concerted mechanism, and the use of a closed-shell approach and different methods for geometry and single-point calculations, we have revisited the chemiluminescence of this molecule. Once again the concerted mechanism was found to be prevailing, and a closed-shell approach was able to rationalize the chemiluminescence of 1,2-dioxetanone. It was once again noted that an open-shell and a step-wise biradical mechanism cannot explain the chemilu minescence of this molecule. (C) 2013 Wiley Periodicals, Inc.