Deuterium Nuclear Quadrupole Resonance Spectra of Nonlinear Hydrogen Bonds
The 2H NQR spectra of several compounds having nonlinear hydrogen bonds (OH⋯O angle of less than 150°) have been obtained at 77 K by a field-cycling double-resonance method: 1,3-diphenyl-1,3-propanedione, salicylamide, 1,4-dihydroxyanthraquinone, tropolone, salicyclic acid, 2-nitrophenol, 1-hydroxy-9-fluorenone, 3-hydroxy-2-naphthoic acid, and 1-hydroxy-2-naphthoic acid. The values obtained for the quadrupole coupling constants are higher than those found in a linear hydrogen bond of the same O⋯O distance. A single-crystal NMR study of 1,3-diphenyl-1,3-propanedione has been carried out at room temperature by a rotating-frame double-resonance experiment. The results show that the principal (z) axis of the deuterium electric field gradient tensor lies nearly along the OH bond direction. Additional 2H NQR spectra for several linear hydrogen-bonded systems in the crystalline benzoic acid, 4-chlorobenzoic acid, 2-bromobenzoic acid, 3-hydroxybenzoic acid, potassium acid phthalate, salicylamide, 3-hydroxy-2-naphthoic acid, and 1-hydroxy-2-naphthoic acid, have also been obtained. In addition, an X-ray structural study of 1-hydroxy-9-fluorenone has provided structural data to test for enhancement of the 2H quadrupole coupling constant for the case of a relatively long nonlinear hydrogen bond. © 1982, American Chemical Society. All rights reserved.
Publication Source (Journal or Book title)
Journal of the American Chemical Society
Brown, T., Butler, L., Curtin, D., Hiyama, Y., Paul, I., & Wilson, R. (1982). Deuterium Nuclear Quadrupole Resonance Spectra of Nonlinear Hydrogen Bonds. Journal of the American Chemical Society, 104 (5), 1172-1177. https://doi.org/10.1021/ja00369a003