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NMR Parameters and Geometries of OHN and ODN Hydrogen Bonds of Pyridine–Acid Complexes
Author(s) -
Limbach HansHeinrich,
Pietrzak Mariusz,
Sharif Shasad,
Tolstoy Peter M.,
Shenderovich Ilya G.,
Smirnov Sergei N.,
Golubev Nikolai S.,
Denisov Gleb S.
Publication year - 2004
Publication title -
chemistry – a european journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.687
H-Index - 242
eISSN - 1521-3765
pISSN - 0947-6539
DOI - 10.1002/chem.200400212
Subject(s) - hydrogen bond , chemistry , pyridine , hydrogen , protonation , crystallography , bond energy , deuterium , bond length , valence (chemistry) , computational chemistry , molecule , atomic physics , organic chemistry , crystal structure , ion , physics
In this paper, equations are proposed which relate various NMR parameters of OHN hydrogen‐bonded pyridine–acid complexes to their bond valences which are in turn correlated with their hydrogen‐bond geometries. As the valence bond model is strictly valid only for weak hydrogen bonds appropriate empirical correction factors are proposed which take into account anharmonic zero‐point energy vibrations. The correction factors are different for OHN and ODN hydrogen bonds and depend on whether a double or a single well potential is realized in the strong hydrogen‐bond regime. One correction factor was determined from the known experimental structure of a very strong OHN hydrogen bond between pentachlorophenol and 4‐methylpyridine, determined by the neutron diffraction method. The remaining correction factors which allow one also to describe H/D isotope effects on the NMR parameters and geometries of OHN hydrogen bond were determined by analysing the NMR parameters of the series of protonated and deuterated pyridine‐ and collidine–acid complexes. The method may be used in the future to establish hydrogen‐bond geometries in biologically relevant functional OHN hydrogen bonds.