title: Cycloreversion of the CO2trimer: a paradigmatic pseudopericyclic [2 + 2 + 2] cycloaddition reaction.
abstract: Very recently, the CO2trimer has been experimentally synthesized, isolated and characterized. This process opens new ways for the withdrawal and storage of this greenhouse gas. The trimer is reported to be stable up to -40 °C, with a lifetime of about 40 min at this temperature. At these or under harsher thermal conditions it reverts to the three monomers. The mechanism of this reaction has been theoretically studied and the electronic character of the associated transition state has been analyzed from a variety of perspectives (energetic, magnetic, electron localization and delocalization functions) which indicate that it has paradigmatic pseudopericyclic character. To allow for a comparative study, the isoelectronic fragmentations of cyclohexane into three units of ethylene and of benzene into three units of acetylene have been included in this work. The study of a similar series of formally forbidden-four-centered [2 + 2] cycloreversions confirmed the pseudopericyclic nature of these reactions when the CO2dimer or trimer is involved.
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias, Campus Universitario, Ourense, Spain.
authors.forename: Roberto
authors.identifier: http://orcid.org/0000-0002-9278-9752
authors.initials: R
authors.lastname: Villar López
authors.affiliation: Departamento de Química Orgánica, Facultad de Ciencias, Campus Universitario, Ourense, Spain.
authors.forename: Olalla
authors.initials: O
authors.lastname: Nieto Faza
authors.affiliation: Kimika Fakultatea, Euskal Herriko Unibertsitatea UPV/EHU, Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Spain and Ikerbasque, Basque Foundation for Science, Bilbao, Spain. ematito@gmail.com.
authors.forename: Eduard
authors.identifier: http://orcid.org/0000-0001-6895-4562
authors.initials: E
authors.lastname: Matito
authors.affiliation: Departamento de Química Orgánica, Facultad de Química, Universidad de Vigo, Campus Lagoas-Marcosende, 36310, Vigo, Spain. carlos.silva@uvigo.es.
authors.forename: Carlos Silva
authors.identifier: http://orcid.org/0000-0003-4955-9844
authors.initials: CS
authors.lastname: López