Proton affinity and heat of formation of vinylimine CH2CHCHNH
Article first published online: 8 APR 2005
Copyright © 1995 John Wiley & Sons, Ltd.
Rapid Communications in Mass Spectrometry
Volume 9, Issue 12, pages 1195–1200, 1995
How to Cite
Bouchoux, G., Salpin, J.-Y., Leblanc, D., Alcaraz, C., Dutuit, O. and Palm, H. (1995), Proton affinity and heat of formation of vinylimine CH2CHCHNH. Rapid Commun. Mass Spectrom., 9: 1195–1200. doi: 10.1002/rcm.1290091222
- Issue published online: 8 APR 2005
- Article first published online: 8 APR 2005
- Manuscript Accepted: 10 AUG 1995
- Manuscript Received: 3 AUG 1995
The vinylimmonium cation [CH2CHCHNH2]+, [1H]+, originating from cyclopentylamine has been studied by photoionization, ion cyclotron resonance mass spectrometry and ab initio molecular orbital calculations. A heat of formation, ΔH[CH2CHCHNH2]+ of 747±7 kJ/mol has been deduced from photoionization experiments, after correction for the thermal energy of the precursor molecules. The proton affinity of vinylimine, CH2 CHCHNH, 1, (PA(1) = 908±4kJ/mol) has been deduced from proton exchange experiments using the ‘bracketing’ technique. This latter, combined with the previously determined ΔH[CH2CHCHNH2]+ leads to ΔH(CH2CHCHNH)=125kJ/mol with a possible error of ±11 kJ/mol. Molecular orbital calculations, conducted at the MP2/6-311 ++G**//MP2/6-31G* + ZPE level, lead to comparable estimates ΔH(CH2 CHCHNH2)+ = 746kJ/mol and ΔH(CH2CHCHNH) = 128–135 (kJ/mol).