Interplay between σ Holes, Anion···H–C, and Cation−π Interactions in Dibromo[2,2]paracyclophane Complexes

Abstract

Theoretical calculations were performed to investigate the interplay between σ−hole, anion−HC and cation−π interactions in the complexes of dibromo[2,2]paracyclophane (DBr[2,2]PCP) with alkali (Li + , Na + , K + ), alkaline earth metal cations (Be 2+ , Mg 2+ , and Ca 2+ ), and halogen anions (F − , Cl − , and Br − ) using the wave function (MP2) and density functional theory (M06-2X and B3LYP) methods with the 6-311++G(d,p) basis set. The study reveals that DBr[2,2]PCP behaves as amphoteric molecule with a predominance of basic character. It prefers to interact with hard cations and hard anions such as Be 2+ and F − through cation−π and anion•••HC interactions, respectively. Substitution of Br by F and Cl atoms in DBr[2,2]PCP decreases slightly the interaction energies of DX[2,2]PCP-halogen complexes (X = F, Cl, and Br) by 2.0 and 0.3 kcal/mol (M06-2X), respectively. The anion−HC interactions in DBr[2,2]PCP complexes are ∼10 kcal/mol stronger (B3LYP; ∼15 kcal/mol at M06-2X and 7 kcal/mol at MP2) than the σ−hole interactions.

Interaction of the Silver(I) Cation with [2.2]Paracyclophane: Experimental and Theoretical Study

“…The interaction of Li + , Na + , K + , Be 2 + , Mg 2 + , Ca 2 + , F À , and Cl À with dibromo[2.2]paracyclophane was studied theoretically by Muya et al. [8] These authors found that dibromo [2.2]paracyclophane could be a scavenger for trace cations and anions because it forms stable complexes with these ions via cation⋅⋅⋅π and anion⋅⋅⋅H À C interactions.…”