Do Traditional, Chlorine-shared, and Ion-pair Halogen Bonds Exist? An ab Initio Investigation of FCl:CNX Complexes

• Published in: The journal of physical chemistry. A, Molecules, spectroscopy, kinetics, environment, & general theory Molecules, spectroscopy, kinetics, environment, & general theory, 2010-12, Vol.114 (49), p.12958-12962
• Main Authors: Del Bene, Janet E, Alkorta, Ibon, Elguero, José
• Format: Article
• Language: English
• Subjects: A: Molecular Structure, Quantum Chemistry, General Theory; Carbon - chemistry; Cyanides - chemistry; Halogens - chemistry; Hydrogen Bonding; Ions - chemistry; Metals, Alkali - chemistry; Nitrogen - chemistry; Protons; Vibration
• ISSN: 1089-5639; 1520-5215
• DOI: 10.1021/jp110295n

Ab initio MP2/aug′-cc-pVTZ calculations have been carried out to determine the structures, binding energies, and bonding of complexes FCl:CNX, with X = CN, NC, NO2, F, CF3, Cl, Br, H, CCF, CCH, CH3, SiH3, Li, and Na. Equation-of-motion coupled cluster calculations have also been carried out to determine the coupling constants 1 J(F−Cl), 1X J(Cl−C), and 2X J(F−C) across these halogen bonds. As the strength of the base is systematically increased, the nature of the halogen bond changes from traditional, to chlorine-shared, to ion-pair. The type of halogen bond present in a complex can be readily determined from its structure, binding energy, AIM bonding analyses, and spin−spin coupling constants. Coupling constants across halogen bonds are compared with corresponding coupling constants across traditional, proton-shared, and ion-pair hydrogen bonds.