Correlation between proton transfer and 35Cl NQR frequency as well as molecular geometry of chloranilic acid in co‐crystals with some organic bases |
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| Authors: | Tetsuo Asaji Janez Seliger Veselko Žagar Hiroyuki Ishida |
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| Institution: | 1. Department of Chemistry, College of Humanities and Sciences, Nihon University, Sakurajosui, Setagaya‐ku, 3‐25‐40, Tokyo 156‐8550, Japan;2. Faculty of Mathematics and Physics, University of Ljubljana, Jadranska 19, 1000 Ljubljana, Slovenia;3. Jozef Stefan Institute, Jamova 39, 1000 Ljubljana, Slovenia;4. Department of Chemistry, Faculty of Science, Okayama University, Okayama 700‐8530, Japan |
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| Abstract: | Proton transfer in hydrogen‐bonded organic co‐crystals of chloranilic acid with some organic bases was investigated by nuclear quadrupole resonance (NQR) spectroscopy. The 35Cl NQR frequencies of chloranilic acid molecule as well as 14N NQR frequencies of the organic base molecule were measured with the conventional pulse methods as well as double‐resonance methods, respectively. The extent of proton transfer in the O···H···N hydrogen bond was estimated from Townes–Dailey analysis of the 14N NQR parameters. The 35Cl NQR frequency and molecular geometry of chloranilic acid are correlated to the extent of proton transfer in the protonation process of the organic base molecule. It is shown that the hydrogen bond affects the π‐electron system of chloranilic acid. Geometry dependence of the O···H···N hydrogen bond, i.e. the H? N valence bond order versus the hydrogen‐bond geometry correlation is also discussed. Copyright © 2010 John Wiley & Sons, Ltd. |
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| Keywords: | NQR 35Cl 14N double resonance hydrogen bond proton transfer molecular structure molecular co‐crystal |
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