Cation-π interactions of inorganic benzenes with Li, Na, and Mg cations: Theoretical insights

Abstract

The interactions of a set of cations (Li+, Na+, and Mg2+) with the π-electron densities of inorganic benzenes, namely, borazine (1), boroxine (2) and boroxazine (3), are studied by means of MP2 calculations using aug-cc-pVTZ basis set. Contributions of the different energy terms into the total interaction energy (Eint) have been assessed by the second-order symmetry-adapted perturbation theory (SAPT2), which demonstrates the importance of both induction and electrostatic components for the attraction in the complexes. These results have been further substantiated by independent gradient model and metal ion affinities calculations. It has been shown that the obtained Eint values for 1 (−36.92, − 18.20, and − 136.33 kcal/mol for Li+, Na+ and Mg2+, respectively) are nearly the same as those for benzene (−39.19, −20.95, and −120.36 kcal/mol for Li+, Na+ and Mg2+, respectively). For the case of in-plane adsorption on 3, Eint for Li+ (−39.81 kcal/mol) and Na+ (−25.43 kcal/mol) are the maximal ones among studied, and they are even larger compared with Eint for benzene. Thus, this molecule as a functional part of nanoclusters is the interesting candidate for the in-plane decoration with cations.