THE N-H STRETCHING VIBRATION BAND IN SEVERAL AROMATIC COMPOUNDS
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Date
1951
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Ohio State University
Abstract
Theoretical work recently reported on pyrrole, indole, carbazole, aniline, and diphenyl amine has included a calculation of the electron density on the nitrogen atoms of each of these $compounds^{1}$. In order to see if these calculated values could be checked by infrared means, a detailed investigation of the absorption bands attributed to the N-H stretching vibrations has been undertaken. A lithium fluoride prism spectrometer was employed, each of these compounds being studied over a wide range of concentration and cell length. This study has resulted in a clarification of contradictory reports on hydrogen bonding made by previous $workers.^{2}$ Evidence will be presented for concluding that in pyrrole the unassociated band is simple, thus removing the experimental basis for Pauling's theory of two types of $pyrrole.^{3}$ A discussion will be included of the absolute values of the unassociated N-H vibration frequencies and their relation with the calculated electron densities of the nitrogen atoms in the corresponding molecules.
Description
$^{1}$ H. C. Longuet-Higgins and C. A. Coulson. Trans. Faraday Soc. 43, 87 (1947); G. Berthier and B. Pullmann, Comptes Rendus. 226, 1775 (1948) $^{2}$ W. Gordy and F. C. Stanford, J. Am. Chem. Soc. 62, 497 (1940); O. R. Wulf and U. Liddell, J. Am. Chem. Soc. 57, 1464 (1935); J. Lecomte Bull. Soc. Chimie, France. 415 (1946) $^{3}$ L. Pauling, J. Am. Chem. Soc. 58, 94 (1936)
Author Institution: Infrared Spectrometry Laboratory, Fisk University
Author Institution: Infrared Spectrometry Laboratory, Fisk University