1- and 2-Adamantyl Radicals and Cations in the Gas Phase:  Thermochemistry and Mass Spectrometry

The heats of formation of the 1- and 2-adamantyl cations and of the 1-adamantyl radical have been measured directly by electron impact appearance energies. The values are Δ f H °[1-adamantyl + ] = 152 ± 3 kcal mol -1, Δ f H °[2-adamantyl + ] = 171 ± 3 kcal mol -1 and Δ f H °[1-adamantyl • ] = 12 ± 3 kcal mol -1 . The results also lead to a value of 16 kcal mol -1 for the heat of formation of the 2-adamantyl radical. Collision-induced dissociation mass spectra of the 1- and 2-adamantyl cations allow low internal energy ions to be distinguished. However, it is shown that at higher internal energies the two ions share a common potential energy surface. This is supported by the statistical mixing of all hydrogen and deuterium atoms, prior to the lowest energy dissociation channel, in the 1-adamantyl-3 d 1 + isotopomer.