Infrared photodissociation spectroscopic and theoretical study of the H<sub>3</sub>C<sub>3</sub>O<sup>+</sup> and D<sub>3</sub>C<sub>3</sub>O<sup>+</sup> acryloyl cations

Abstract

The carbocations, H3C3O+ and D3C3O+ are produced via pulsed laser vaporization of a graphite target in supersonic expansions of helium seeded with carbon monoxide and acetylene or methane. The infrared spectra are measured via mass-selected infrared photodissociation spectroscopy of their CO-tagged [H3C3O·CO]+ and [D3C3O·CO]+ cation complexes. The geometry of the cation complex is determined by the infrared spectra in conjunction with theoretical calculations. The H3C3O+ and D3C3O+ core cations are determined to be acryloyl cations with 1A ¢ electronic ground state and C s symmetry. The AdNDP bonding analysis indicates that besides the localized two-center-two-electron (2c-2e) C–O, C–C, and C–H σ bonds as well as 2c-2e CO π bonds, there is a delocalized three-center-two-electron (3c-2e) CCC π bond.