title: Competition between halogen, dihalogen and hydrogen bonds in bromo- and iodomethanol dimers.
abstract: O-H...X and O-H...O H-bonds as well as C-X...X dihalogen and C-X...O halogen bonds have been investigated in halomethanol dimers (bromomethanol dimer, iodomethanol dimer, difluorobromomethanol…bromomethanol complex and difluoroiodomethanol…iodomethanol complex). Structures of all complexes were optimized at the counterpoise-corrected MP2/cc-pVTZ level and single-point energies were calculated at the CCSD(T)/aug-cc-pVTZ level. Energy decomposition for the bromomethanol dimer complex was performed using the DFT-SAPT method based on the aug-cc-pVTZ basis set. OH...O and OH...X H-bonds are systematically the strongest in all complexes investigated, with the former being the strongest bond. Halogen and dihalogen bonds, being of comparable strength, are weaker than both H-bonds but are still significant. The strongest bonds were found in the difluoroiodomethanol…iodomethanol complex, where the O-H...O H-bond exceeds 7 kcal mol(-1), and the halogen and dihalogen bonds exceed 2.5 and 2.3 kcal mol(-1), respectively. Electrostatic energy is dominant for H-bonded structures, in halogen bonded structures electrostatic and dispersion energies are comparable, and, finally, for dihalogen structures the dispersion energy is clearly dominant.
authors.affiliation: Department of Chemistry, Xavier University of Louisiana, New Orleans, LA 17025, USA. kev.e.riley@gmail.com
authors.forename: Kevin E
authors.initials: KE
authors.lastname: Riley
authors.forename: Jan
authors.initials: J
authors.lastname: Rezáč
authors.forename: Pavel
authors.initials: P
authors.lastname: Hobza
mesh_terms: D001966:Bromine / Q000737:chemistry*; D006860:Hydrogen Bonding; D007455:Iodine / Q000737:chemistry*; D000432:Methanol / Q000737:chemistry; D008958:Models, Molecular; D011789:Quantum Theory
chemical_list: D007455:Iodine; D001966:Bromine; D000432:Methanol