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Charge localization and aromatic stabilization in large ring ions: Mass spectra of ms‐porphyrins
Author(s) -
MeotNer M.,
Adler A. D.,
Green J. H.
Publication year - 1974
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.1210090110
Subject(s) - fragmentation (computing) , chemistry , metal , mass spectrum , pyrrole , ion , tetra , ring (chemistry) , medicinal chemistry , metal ions in aqueous solution , derivative (finance) , deuterium , organic chemistry , atomic physics , physics , financial economics , economics , computer science , operating system
The major mass spectrometric fragments of ms‐tetraphenylporphin and ms‐tetra(p‐chloro)phenylporphin are [M H] + ˙ and [M Cl] + ˙, respectively. Metal derivatives of these compounds give a modified characteristic fragmentation pattern with peak groups ending in the ions [M 4H] + ˙, [M ϕ 5H] + ˙ and [M 2ϕ 2H] + ˙ for the metallo ms‐tetraphenylporphins, and [M ϕCl 2Cl 3H] + ˙ and [M 2ϕCl Cl H] + ˙ for Mgms‐tetra( p ‐chloro)phenylporphin. Deuterated metal derivatives indicate random hydrogen loss from both phenyl and pyrrole carbons. However, metal substituents do not significantly modify the fragmentation pattern in the case of ms‐tetra( p ‐methoxy)phenylporphin. These patterns can be explained in terms of aromatic stabilization of the fragmentation products, coupled with charge localization on the π system in the free base, on the metal atom in the metallo derivatives and on the methoxy function in the p‐methoxyphenyl derivative.