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Activation of the Disulfide Bond and Chalcogen–Chalcogen Interactions: An Experimental (FTICR) and Computational Study
Author(s) -
Esseffar M'Hamed,
Herrero Rebeca,
Quintanilla Esther,
Dávalos Juan Z.,
Jiménez Pilar,
Abboud JoséLuis M.,
Yáñez Manuel,
Mó Otilia
Publication year - 2007
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200600733
Subject(s) - chalcogen , chemistry , methanethiol , protonation , reaction rate constant , computational chemistry , yield (engineering) , gibbs free energy , equilibrium constant , transition state , crystallography , ion , kinetics , thermodynamics , organic chemistry , sulfur , catalysis , physics , quantum mechanics
Dimethyldisulfide ( I ) is the simplest model of the biologically relevant family of disubstituted disulfides. The experimental study of its gas‐phase protonation has provided, we believe for the first time, a precise value of its gas‐phase basicity. This value agrees within 1 kJ mol −1 with the results of G3 calculations. Also obtained for the first time was the reaction rate constant for the bimolecular reaction between I and its protonated form, I H + , to yield methanethiol and a dimethyldithiosulfonium ion. This constant is of the order of magnitude of the collision limit. A computational mechanistic study based on the energetic profile of the reaction, completed with Fukui's and Bader's treatments of the reactants and transition states fully rationalizes the regioselectivity of the reaction as well as the existence of a shallow, flat Gibbs energy surface for the reaction. The mechanistic relevance of the chalcogen–chalcogen interaction and the CH ⋅⋅⋅ S bonds has been demonstrated.