Is ionized cyclopropylamine cyclic?

combination of experiments based on proton transfer reactions monitored in a Fourier transform ion cyclotron resonance (FTICR) mass spectrometer and molecular orbital calculations up to the G2 and the CBS-Q levels demonstrates that the structure of the ions produced by electron ionization of cyclopropylamine, 1, and relaxed at thermal energy, possess the ionized l-propene amine structure [CH3CHCHNH2](.+), 3(.+). The experimental deprotonation enthalpy of ions 3(.+) is equal to 915.3 +/- 3.2 kJ mol(-1). CBS-Q calculations are in good agreement with experiment. A value of 919-923 kT mol(-1) is calculated for the deprotonation enthalpy of ions 3(.+); 298 R heat of formation values of 852 kJ mol(-1) and 783 kJ mol(-1) are predicted from G2 atomization energies for ions 2(.+) and 3(.+), respectively. The heat of formation 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 Mass Spectrom 199 (2000) 59-69) (C) 2000 Elsevier Science B.V.