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  • Title: NMR parameters and geometries of OHN and ODN hydrogen bonds of pyridine-acid complexes.
    Author: Limbach HH, Pietrzak M, Sharif S, Tolstoy PM, Shenderovich IG, Smirnov SN, Golubev NS, Denisov GS.
    Journal: Chemistry; 2004 Oct 11; 10(20):5195-204. PubMed ID: 15372662.
    Abstract:
    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.
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