Ph(R)IF⋯HF (R = Me, Et, iPr, tBu) interaction: A strong hydrogen bond between hypervalent iodine compounds and HF

Abstract

For the first time, the intermolecular hydrogen bonding interactions between polyvalent iodine compounds and hydrogen fluoride (HF) have been studied using M06-2X/SDD-6-311++G(d, p) method. The computational results show that, compared with iodine(I) compound IF, both the iodine(III) compound Ph(Et)IF and the iodine(V) compound Ph(Et)3IF have strong hydrogen bonding interactions with HF and the binding energies are about -21.00kcal/mol. Geometry analysis, natural bond orbital (NBO) analysis, energy decomposition analysis, electrostatic potential (ESP) analysis on molecular vdW surface and topological analysis for the bond critical points (BCPs) suggest that these strong interactions are not only electrostatic but also highly covalent in nature. In addition, our computational studies indicate that owing to the lower electronegativity of Cl and Br atoms relative to that of F atom, the compounds Ph(Et)ICl and Ph(Et)IBr have much weaker hydrogen bonding interactions with HF than Ph(Et)IF. Moreover, the electronic effects of substituents at the iodine center of the hypervalent iodine (III) compounds on the strength of the hydrogen bonds have also been studied and the results show that the alkyl groups such as methyl, ethyl, isopropyl and tert-butyl groups can enhance the hydrogen bonding interaction obviously relative to other types of substituents. And the hydrogen bond in complex Ph(iPr)IF⋯HF is very strong with binding energy of −22.44kcal/mol.