G. Bouchoux et al., PROTON AFFINITY AND HEAT OF FORMATION OF VINYLIMINE CH2=CHCH=NH, Rapid communications in mass spectrometry, 9(12), 1995, pp. 1195-1200
The vinylimmonium cation [CH2=CHCHNH2](+), [1H](+), originating from c
yclopentylamine has been studied by photoionization, ion cyclotron res
onance mass spectrometry and ab initio molecular orbital calculations.
A heat of formation, Delta H degrees(1300)[CH2=CHCHNH2](+) of 747 +/-
7 kJ/mol has been deduced from photoionization experiments, after cor
rection for the thermal energy of the precursor molecules, The proton
affinity of vinylimine, CH2=CHCHNH, 1, (PA(1)=908 +/- 4 kJ/mol) has be
en deduced from proton exchange experiments using the 'bracketing' tec
hnique. This latter, combined with the previously determined Delta H d
egrees(1300) [CH2=CHCHNH2](+) leads to Delta H degrees(1300)(CH2=CHCHN
H)=125 kJ/mol with a possible error of +/- kJ/mol. Molecular orbital c
alculations, conducted at the MP2/6-311++G*//MP2/6-31G*+ZPE level, le
ad to comparable estimates (Delta H degrees(1300)(CH2=CHCHNH2)(+)=746
kJ/mol and Delta H degrees(1300)(CH2=CHCHNH)=128-135 kJ/mol).