title: Cooperativity in hydrogen-bonded interactions: ab initio and "atoms in molecules" analyses.
abstract: The H(2)CO...(HF)(n) (n = 1, ..., 9) complexes were investigated using the MP2 method and the following basis sets: 6-311++G(d,p), aug-cc-pVDZ and aug-cc-pVTZ. It was found that the cooperativity effect enhances significantly the F-H...O hydrogen bond; in some of cases one can detect the covalent nature of hydrogen bonding. To deepen the nature of the interactions investigated, the scheme of decomposition of the interaction energy was applied; for stronger H-bonds where the cooperativity is more important, the delocalization energy term increases. The ratio of delocalization energy to electrostatic energy increases for stronger hydrogen bonds where the proton...acceptor distance is shorter. The Bader theory was also applied, and it was found that for stronger H-bonds the electronic energy density at the proton...acceptor bond critical point is negative and may be attributed to the partly covalent interaction.
authors.affiliation: Department of Quantum Chemistry, Institute of Chemistry, Nicolaus Copernicus University, 7, Gagarin St., 87-100 Toruń, Poland.
authors.forename: Marcin
authors.initials: M
authors.lastname: Ziółkowski
authors.forename: Sławomir J
authors.initials: SJ
authors.lastname: Grabowski
authors.forename: Jerzy
authors.initials: J
authors.lastname: Leszczynski
mesh_terms: D000465:Algorithms; D001665:Binding Sites; D002248:Carbon Monoxide / Q000737:chemistry*; D006858:Hydrofluoric Acid / Q000737:chemistry*; D006859:Hydrogen / Q000737:chemistry*; D006860:Hydrogen Bonding; D055672:Static Electricity; D013816:Thermodynamics
chemical_list: D002248:Carbon Monoxide; D006859:Hydrogen; D006858:Hydrofluoric Acid