The sites of a molecule that tend to be most reactive are the sites with the largest charge (electrostatically-controlled reactions) or the sites with the greatest electron transfer (Fukui-controlled reactions). But some molecules fall between these two paradigms. It is also frequently observed that only a few sites in a molecule are reactive and that the characteristic reactivity of these sites persist for a wide variety of incoming reagents [1]. As such the details of the incoming molecule can largely be neglected. With these observations in mind a reactivity indicator can be constructed by studying the molecular response to a simplified “model reagent” that mimics the charge and Fukui effects of the incoming molecule [2]. The proposed indicator can be computed easily from the charges at each site of the molecule and from the charges at each site of the molecule with one fewer electron (if the molecule of interest is a nucleophile) or one additional electron (if the molecule of interest in an electrophile). Charges can be computed with a wide variety of quantum chemistry packages including Gaussian, which is the program used in my study. In this talk I will discuss the formulation, computational scheme, and results that come from using this model. In particular, the model will be applied to a number of systems where the reactive sites are difficult (or even impossible) to describe using conventional methods, including boraphenanthrenes, which are molecules where frontier orbital theory fails to predict the correct reaction products [3]. This method is also effective for discerning the reactivity of ambidentate ligands (e.g., thiocyanate, nitrite, and sulfite) and for electrophiles with both hard and soft reactive centers (e.g., dimethyl carbonate, N-methyl-N-nitrosotoluene-p-sulfonamide) [4]. [1] P.W. Ayers, J.S.M. Anderson and J. Bartolotti, Int. J. Quantum Chem., 101, (2005). [2]J.S.M. Anderson, J. Melin and P.W. Ayers, J. Chem. Th. Comp., 3, (2007). [3]J.S.M. Anderson, J. Melin and P.W. Ayers, J. Chem. Th. Comp., 3, (2007). [4]J.S.M. Anderson and P.W. Ayers Phys. Chem. Chem. Phys., 9, (2007).

Conceptual DFT formulated general purpose reactivity indicator for predicting and classifying the reactivity of sites within a molecule

255th National Meeting (2018)

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