Reconciling Electrostatic and n→π* Orbital Contributions in Carbonyl Interactions |
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Authors: | Kamila B Muchowska Dominic J Pascoe Stefan Borsley Ivan V Smolyar Ioulia K Mati Catherine Adam Gary S Nichol Kenneth B Ling Scott L Cockroft |
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Institution: | 1. EaStCHEM School of Chemistry, The University of Edinburgh, Joseph Black Building, David Brewster Road, Edinburgh, EH9 3FJ UK;2. Syngenta, Jealott's Hill International Research Centre, Bracknell, Berkshire, RG42 6EY UK |
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Abstract: | Interactions between carbonyl groups are prevalent in protein structures. Earlier investigations identified dominant electrostatic dipolar interactions, while others implicated lone pair n→π* orbital delocalisation. Here these observations are reconciled. A combined experimental and computational approach confirmed the dominance of electrostatic interactions in a new series of synthetic molecular balances, while also highlighting the distance-dependent observation of inductive polarisation manifested by n→π* orbital delocalisation. Computational fiSAPT energy decomposition and natural bonding orbital analyses correlated with experimental data to reveal the contexts in which short-range inductive polarisation augment electrostatic dipolar interactions. Thus, we provide a framework for reconciling the context dependency of the dominance of electrostatic interactions and the occurrence of n→π* orbital delocalisation in C=O⋅⋅⋅C=O interactions. |
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Keywords: | computational chemistry conformation analysis delocalization electrostatic interactions noncovalent interactions |
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