Formation and Evolution of H2C3O+• Radical Cations: A Computational and Matrix Isolation Study
journal contributionposted on 2022-04-29, 22:43 authored by Pavel V. Zasimov, Daniil A. Tyurin, Sergey V. Ryazantsev, Vladimir I. Feldman
The family of isomeric H2C3O+• radical cations is of great interest for physical organic chemistry and chemistry occurring in extraterrestrial media. In this work, we have experimentally examined a unique synthetic route to the generation of H2C3O+• from the C2H2···CO intermolecular complex and also considered the relative stability and monomolecular transformations of the H2C3O+• isomers through high-level ab initio calculations. The structures, energetics, harmonic frequencies, hyperfine coupling constants, and isomerization pathways for several of the most important H2C3O+• isomers were calculated at the UCCSD(T) level of theory. The complementary FTIR and EPR studies in argon matrices at 5 K have demonstrated that the ionized C2H2···CO complex transforms into the E-HCCHCO+• isomer, and this latter species is supposed to be the key intermediate in further chemical transformations, providing a remarkable piece of evidence for kinetic control in low-temperature chemistry. Photolysis of this species at λ = 410–465 nm results in its transformation to the thermodynamically most stable H2CCCO+• isomer. Possible implications of the results and potentiality of the proposed synthetic strategy to the preparation of highly reactive organic radical cations are discussed.
unique synthetic routesup >+• supproposed synthetic strategymatrix isolation studyhyperfine coupling constantsab initio physical organic chemistry3 sub2 sube temperature chemistrychemistry occurringuccsd (remarkable piecerelative stabilityradical cationspossible implicationsmonomolecular transformationskinetic controlkey intermediateisomerization pathwaysharmonic frequenciesgreat interestextraterrestrial mediaexperimentally examinedepr studiescomplementary ftirchemical transformationsargon matricesalso considered>- hcchco5 k