Hydrogen bonding from a valence bond theory perspective: the role of covalency.

Autor: Nemes CT; Department of Chemistry, Biochemistry, and Physics Marist College, Poughkeepsie, NY 12601, USA., Laconsay CJ, Galbraith JM
Jazyk: angličtina
Zdroj: Physical chemistry chemical physics : PCCP [Phys Chem Chem Phys] 2018 Aug 15; Vol. 20 (32), pp. 20963-20969.
DOI: 10.1039/c8cp03920h
Abstrakt: A valence bond theory based method has been developed to decompose hydrogen bond energies into contributions from geometry, electrostatics, polarization and charge transfer. This decomposition method has been carried out for F-HFH, F-HOH2, F-HNH3, HO-HOH2, HO-HNH3, and H2N-HNH3. Localized valence bond self-consistent field (L-VBSCF) and localized breathing orbital valence bond (L-BOVB) calculations were performed at the PBEPBE/aug-cc-pVDZ optimized geometries. It is shown that inclusion of valence bond structures that explicitly include charge transfer account for at least 32% (likely over half) of the hydrogen bond energy of all systems studied, indicating the dominant role of covalency. This is in agreement with calculated bond lengths, geometry deformation energies, and polarization energies. Electrostatic effects were found to play only a minor role in contrast to some widely held ideas regarding the nature of hydrogen bonding.
Databáze: MEDLINE