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Rationalization of scrambling processes among [C 2 H 3 O] + ions
Author(s) -
Nobes Ross H.,
Radom Leo
Publication year - 1986
Publication title -
organic mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 0030-493X
DOI - 10.1002/oms.1210210705
Subject(s) - scrambling , metastability , ion , dissociation (chemistry) , protonation , chemistry , ab initio , valence (chemistry) , ab initio quantum chemistry methods , computational chemistry , crystallography , atomic physics , physics , molecule , organic chemistry , philosophy , linguistics
Scrambling data for the three observed [C 2 H 3 O] + isomers, namely [CH 3 CO] + ( a ), [CH 2 COH] + ( b ) and ( c ), are rationalized by using ab initio molecular orbital calculations. For ions a and c , processes leading to scrambling of the carbon atoms require substantially more energy than the threshold for decomposition to [CH 3 ] + + CO. Accordingly, little or no carbon scrambling is predicted nor is any observed in the metastable dissociation of a and c . The observed carbon scrambling in b prior to metastable dissociation to [CH 3 ] + + CO has previously been explained in terms of a mechanism involving the oxiranyl cation ( c ). However, this mechanism is shown to be unlikely because of the high energies involved. An alternative lower‐energy pathway involving the intermediacy of protonated oxirene ( h ) is proposed. Such a mechanism is fully compatible with the experimental data.