N energy of interactions in H-bonds

Crystallographic literature is full of information on the so-called close interatomic contacts, which in the case of distances between H-atoms and electron donating atoms are used as a criterion of H-bond existence. If this distance is shorter than the sum of van der Waals radii - then the H-bond type interaction is assumed 

The energies of H...0 and H...N interaction in Figs 9 and 10 were estimated in this way. It is worth mentioning that the energies of O...H interactions estimated from the geometry of neutron diffraction measurements for 43 H-bonded systems obtained by use of the Lippincott and Schroder model and by eq. (3) lead to the qualitatively equivalent results the correlation coefficient for this dependence is r = 0.998 [33]. 

This model turned out to be very useful for interpretation of the properties of the systems with intramolecular 0-H. ..O bonds. Both the location of the IR v(OH) v band in IR and the chemical shift 5(H) in H NMR are often used as empirical indicators of the hydrogen bond. Both of them correlate well with the O...H interaction energy, as shown in Figs 9 and 10. 

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