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Exploring the potential energy hypersurface of histamine monocation: Tautomerism in gas phase
Author(s) -
Tapia O.,
Cárdenas R.,
Smeyers Y. G.,
HernándezLaguna A.,
Rández J. J.,
Rández F. J.
Publication year - 1990
Publication title -
international journal of quantum chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.484
H-Index - 105
eISSN - 1097-461X
pISSN - 0020-7608
DOI - 10.1002/qua.560380513
Subject(s) - tautomer , chemistry , imidazole , transition state , ab initio , maxima and minima , potential energy , ab initio quantum chemistry methods , hypersurface , computational chemistry , potential energy surface , histamine , crystallography , stereochemistry , molecule , atomic physics , organic chemistry , catalysis , physics , mathematics , medicine , mathematical analysis
The potential energy hypersurface of the histamine monocation is determined by ab initio methods at the STO ‐4G level using analytical gradient techniques. Three transition states and two minima have been found for the N τ H tautomer. One of the transition states connects the trans conformational region with a minimum gauche structure, where the proton of the ammonium group is approximately halfway between the N π of the imidazole group and the N of the ammonium group, but nearer to the N π . This minimum connects the potential energy surface of the N τ H tautomer with the imidazolium one. In the latter region, three transition states and two minima have been found. Critical points are discussed in relation with experimental data and histamine H 2 receptor models.