Correlating the site selectivity of protonation in some ambidentate molecules in terms of the dual descriptor
Department of Chemistry, University of Kalyani,
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Received in final form: 2 October 2011
Published online: 27 March 2012
The physico-chemical process of protonation is associated with the energy lowering phenomenon. For ambivalent molecules having more than one lone pairs at different sites, the protonation occurs preferentially. Preferred site of protonation is an important physico-chemical input in suggesting and modeling reaction mechanism involving such molecules. Locating the preferred site of protonation in ambivalent molecules is an intriguing problem of experimental as well as theoretical chemistry. Toro-Labbe et al. introduced a new Density Functional based descriptor in terms of the difference between nucleophilic and electrophilic Fukui functions – known as dual descriptor (Δf). It has been shown that dual descriptor (Δf) provides useful information on both stabilizing and destabilizing interactions between a nucleophile and an electrophile and helps to identify the electrophilic/nucleophilic behavior of a specific site within a molecule. We have invoked this dual descriptor (Δf) theoretically locating the preferred site of protonation, an electrophilic reaction, of a series of ambidentate molecules whose preferred sites of protonation are known experimentally. We have found that theoretical predictions in terms of computed dual descriptor (Δf) values regarding the preferred sites of protonation in such molecules have one to one correspondence with the experimental findings.
Key words: Quantum Information
© EDP Sciences, Società Italiana di Fisica and Springer-Verlag 2012