ISSN:
0947-6539
Keywords:
ab initio calculations
;
glycinamide
;
mass spectrometry
;
protonations
;
quantum chemistry
;
Chemistry
;
General Chemistry
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The potential energy hypersurface of protonated glycinamide (GAH+) has been investigated experimentally and theoretically. The calculated G2(MP2) value for the proton affinity of glycinamide, PAcalcd = 919 kJ mol-1, is in good agreement with the measured value of 908PAexp〈914kJ mol-1. The fact that the amide group is a better hydrogenbond acceptor explains why glycinamide has a higher PA than glycine. Proton transfer experiments with glycinamide performed in a Fourier transform mass spectrometer and analysis of metastable GAH+ ions in a four-sector mass spectrometer show that the lowest-energy unimolecular reactions are two distinct processes: 1) loss of CO, which has a substantial barrier for the reverse reaction, and 2) loss of CO plus NH3, which has no barrier for the reverse reaction. Ab initio quantum chemical calculations give a reaction model that is consistent with the observed fragmentation pattern.
Additional Material:
9 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/chem.1460020915
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