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CH Bond Dissociation Energies of Polycyclic Aromatic Hydrocarbon Molecular Cations: Theoretical Interpretation of the (M‐1) + Peak in the Mass Spectra
Author(s) -
Fujiwara Kenji,
Harada Akinori,
Aihara Junichi
Publication year - 1996
Publication title -
journal of mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.475
H-Index - 121
eISSN - 1096-9888
pISSN - 1076-5174
DOI - 10.1002/(sici)1096-9888(199611)31:11<1216::aid-jms409>3.0.co;2-m
Subject(s) - chemistry , molecular orbital , bond dissociation energy , dissociation (chemistry) , polycyclic aromatic hydrocarbon , molecule , mass spectrum , polyatomic ion , computational chemistry , hydrocarbon , bond energy , dehydrogenation , ion , organic chemistry , catalysis
PM3 molecular orbital calculations were carried out to estimate CH bond dissociation energies of 13 polycyclic aromatic hydrocarbon (PAH) molecular cations. The dissociation energy of a CH bond turned out to be almost independent of the size of the molecular cation and the environment in the cation. Therefore, when a high‐energy electron impacts a PAH molecule, all hydrogen atoms must be detached with almost equal probability from the resulting molecular cation. It follows that the [M‐1] + peak in the mass spectra of PAH molecules cannot be assigned to any particular arylium ion. The highest and the next highest occupied π‐molecular orbital in some PAH molecular cations are exchanged on dehydrogenation.