Ethyl cation appearance energy

For both the vinyl and ethyl cations, disagreements between experimental appearance energy data and ionization energies of the radicals have been a major problem, by as much as 42 kJ mol" for vinyl cation and 21 kJ mol" for ethyl cation. The problem has been aggravated by the number of candidate.s for where the problem could lie, including uncertainty in the heats of formation of the radicals (particularly for vinyl). 

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