DUGi

An Assessment of the Validity of the Maximum Hardness Principle in Chemical Reactions

http://dugi.udg.edu/item/http:@@@@hdl.handle.net@@10256@@11394

We have computationally explored the fulfillment of the Maximum Hardness Principle in chemical reactions. To this end we have selected a well-defined series of 34 exothermic chemical reactions (the so-called BH76 test) and we have calculated the hardness of reactants, transition state, and products. Our results show that for only 18% of the reactions studied the hardness of the reactants is, at the same time, lower than that of the products and greater than that of the transition state, in agreement with the Maximum Hardness Principle. In most reactions we find that either the transition state has a higher hardness than the reactants or the reactants are harder that the products or both, and, therefore our results show that the Maximum Hardness Principle is disobeyed in most chemical reactions

We thank the following organizations for financial support: the Ministerio de Ciencia e Innovacion (MICINN, project numbers CTQ2011-23156/BQU, CTQ2011-25086/BQU, and Ramon y Cajal contract for JP) and the DIUE of the Generalitat de Catalunya (project numbers 2009SGR637 and 2009SGR528). Support for the research of M. Sola was received through the ICREA Academia 2009 prize for excellence in research funded by the DIUE of the Generalitat de Catalunya. Financial support from MICIN (Ministry of Science and Innovation, Spain) and the FEDER fund (European Fund for Regional Development) was provided

Sociedad Química de México