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Molecular conformation of N,N′-diarylthioureas: An assessment by 1H NMR and infrared spectroscopy

✍ Scribed by L. V. Sudha; S. Manogaran; D. N. Sathyanarayana

Publisher
John Wiley and Sons
Year
1985
Tongue
English
Weight
748 KB
Volume
23
Category
Article
ISSN
0749-1581

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✦ Synopsis

Abstract

Several N,N′‐dipyridyl‐ and N‐phenyl‐N′‐pyridyl‐thioureas were examined in different solvents at various temperatures by ^1^H NMR in order to study their conformational properties. The influence of concentration and the methyl substituent in the pyridine ring on the chemical shifts of the NH and pyridine groups was investigated. The observed chemical shifts are analysed in terms of the conformational properties of the molecules. Free energy barriers to the internal rotation about the CN bonds have been determined. Infrared spectra have been measured to supplement the NMR studies. Intramolecular hydrogen bonding played a major role in the preferred conformation of pyridylthioureas. The data further revealed an interesting dynamic exchange phenomenon occurring in symmetric N,N′‐dipyridylthioureas between two intramolecularly hydrogen bonded conformers.

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