Article

Surfing π Clouds for Noncovalent Interactions: Arenes versus Alkenes

Abil E. AlievDepartment of Chemistry, University College London, 20 Gordon Street, London WC1H 0AJ (UK). [email protected]Josephine R. T. ArendorfDepartment of Chemistry , University College London , 20 Gordon Street , London , WC1H 0AJ , UKIlias PavlakosDepartment of Chemistry , University College London , 20 Gordon Street , London , WC1H 0AJ , UKRafael B. MorenoDepartment of Chemistry , University College London , 20 Gordon Street , London , WC1H 0AJ , UKMichael J. PorterDepartment of Chemistry , University College London , 20 Gordon Street , London , WC1H 0AJ , UKHenry S. RzepaDepartment of Chemistry, Imperial College London South Kensington Campus, London SW7 2AZ, UKWilliam B. MotherwellDepartment of Chemistry , University College London , 20 Gordon Street , London , WC1H 0AJ , UK

2014en

ABI

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 C(α) 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.

Identifiers

DOI: 10.1002/anie.201409672

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