Ab initio study on the thermochemistry of vinyl radical and cation

The G2 calculations have been used to resolve current discrepancies in the experimental data on the thermochemistry of vinyl radical (1) and cation (3). The calculated enthalpies of formation for 1 and 3 (ΔHf 298 (1) =301.4 and ΔHf 298 (3) =1116.8 kJ/mol) agree well with some recent experimental estimates. While the G2 value of the adiabatic ionization energy for 1 (8.61 eV) differs from the recommended value of 8.25 eV, it is in very good agreement with the earlier experimental data of J. Berkowitz, C.A. Mayhew and R. Ruscic (J. Chem. Phys. 88 (1988) 7396): 8.59±0.03 eV.