Surfing π Clouds for Noncovalent Interactions: Arenes versus Alkenes |
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| Authors: | Dr Abil E Aliev Dr Josephine R T Arendorf Dr Ilias Pavlakos Dr Rafael B Moreno Dr Michael J Porter Prof Henry S Rzepa Prof William B Motherwell |
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| Institution: | 1. Department of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (UK);2. Department of Chemistry, Imperial College London, South Kensington campus, London, SW7 2AZ (UK) |
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| Abstract: | A comparative study of molecular balances by NMR spectroscopy indicates that noncovalent functional‐group interactions with an arene dominate over those with an alkene, and that a π‐facial intramolecular hydrogen bond from a hydroxy group to an arene is favored by approximately 1.2 kJ mol?1. The strongest interaction observed in this study was with the cyano group. Analysis of the series of groups CH2CH3, CH?CH2, C?CH, and C?N shows a correlation between conformational free‐energy differences and the calculated charge on the Cα atom of these substituents, which is indicative of the electrostatic nature of their π interactions. Changes in the free‐energy differences of conformers show a linear dependence on the solvent hydrogen bond acceptor parameter β. |
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| Keywords: | conformational analysis molecular balances NMR spectroscopy noncovalent interactions π interactions |
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