Theoretical Study on Cooperativity Effects between Anion-π and Halogen-Bonding Interactions

• Published in: Chemphyschem 2011-10, Vol.12 (15), p.2742-2750
• Main Authors: Estarellas, Carolina, Frontera, Antonio, Quiñonero, David, Deyà, Pere M.
• Format: Article
• Language: English
• Subjects: Ab initio calculations; Atomic and molecular physics; Calculations and mathematical techniques in atomic and molecular physics (excluding electron correlation calculations); cooperative effects; Electronic structure of atoms, molecules and their ions: theory; Exact sciences and technology; noncovalent interactions; Physics; supramolecular chemistry; through-bond interactions
• ISSN: 1439-4235; 1439-7641
• DOI: 10.1002/cphc.201100492

This article analyzes the interplay between lone pair–π (lp–π) or anion–π interactions and halogen‐bonding interactions. Interesting cooperativity effects are observed when lp/anion–π and halogen‐bonding interactions coexist in the same complex, and they are found even in systems in which the distance between the anion and halogen‐bond donor molecule is longer than 9 Å. These effects are studied theoretically in terms of energetic and geometric features of the complexes, which are computed by ab initio methods. Bader′s theory of “atoms in molecules” is used to characterize the interactions and to analyze their strengthening or weakening depending upon the variation of charge density at critical points. The physical nature of the interactions and cooperativity effects are studied by means of molecular interaction potential with polarization partition scheme. By taking advantage of all aforementioned computational methods, the present study examines how these interactions mutually influence each other. Additionally, experimental evidence for such interactions is obtained from the Cambridge Structural Database (CSD). Interesting cooperativity effects are observed in complexes in which lone pair–π or anion–π interactions coexist with halogen bonding. These through‐bond effects, which can be quantified by the cooperativity energy Ecoop, are found even in systems in which the distance between the anion and the halogen‐bond donor molecule is longer than 9 Å (see picture).