Is ionized cyclopropylamine cyclic?

combination of experiments based on proton transfer reactions monitored in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer and m olecular orbital calculations up to the G2 and the CBS-Q levels demonstrate s that the structure of the ions produced by electron ionization of cyclopr opylamine, 1, and relaxed at thermal energy, possess the ionized l-propene amine structure [CH3CHCHNH2](.+), 3(.+). The experimental deprotonation ent halpy of ions 3(.+) is equal to 915.3 +/- 3.2 kJ mol(-1). CBS-Q calculation s are in good agreement with experiment. A value of 919-923 kT mol(-1) is c alculated for the deprotonation enthalpy of ions 3(.+); 298 R heat of forma tion values of 852 kJ mol(-1) and 783 kJ mol(-1) are predicted from G2 atom ization energies for ions 2(.+) and 3(.+), respectively. The heat of format ion of [CH2CHCHNH2](+) ions has been evaluated to 757.6 +/- 5.7 kJ mol(-1) from experiment and 755.8 kJ mol(-1) from G2 atomization energy. (Int J Mas s Spectrom 199 (2000) 59-69) (C) 2000 Elsevier Science B.V.