A STUDY OF INTRAMOLECULAR HYDROGEN BONDS C-H center dot center dot center dot X (X = N, O) WITHIN THE THEORY OF THE ELECTRON LOCALIZATION FUNCTION

作者：Vashchenko A V^*; Afonin A V

来源：Journal of Structural Chemistry, 2014, 55(6): 1010-1018.

DOI：10.1134/S002247661406002X

• intramolecular hydrogen bond
• electron localization function
• bifurcation index of core and valence electrons
• quantum theory " Atoms in molecules&quot

Electron localization functions (ELFs) are calculated at the hydrogen bond critical points for a number of molecules having the intramolecular hydrogen bond C-Ha <-X (X = N, O). It is shown that the values of the core and valence electrons bifurcation index (CVBI) are positive in all cases. This enables the characterization of the studied hydrogen bonds as weak interactions of mainly electrostatic nature. For stronger intramolecular hydrogen bonds N-Ha <-O with a significant contribution of covalence to the bonding, the bifurcation index is negative. A relationship between the parameters calculated within the theory of the electron localization ELF) and the quantum theory "Atoms in Molecules" (QTAIM) is observed. In the H-1 NMR spectra, the resonance shift of the bridging hydrogen atom, induced by a hydrogen bond is much smaller for the hydrogen bonds having a positive bifurcation index than that for the hydrogen bonds with the negative bifurcation index, and the interatomic Ha <-X distance is much longer in the former case. In the IR spectra the positive bifurcation index corresponds to a blue shift of the stretching vibration of the covalent bond of the hydrogen donor due to the hydrogen bonding and the negative bifurcation index corresponds to the red shift of this band.

• 出版日期2014-11