A comprehensive computational investigation of the enthalpies of formation and proton affinities of C4H7N and C3H3ON compounds

The results of electronic structure studies aimed at determining accurate enthalpies of formation and proton affinities for a comprehensive set of C4H7N and C3H3ON compounds are reported. The calculated thermodynamic values are rationalized in terms of the nitrogen functionality and the influence of unsaturated C–C bonding environments. Using these results, it is proposed that a previously unidentified mass 70 amu tropospheric ion is the protonated form of 1-pyrroline, an unsaturated nitrogen heterocyclic compound emitted into the atmosphere by both plant and animal biological activity. © 2003 Elsevier Science B.V. All rights reserved.