O- vs. N-protonation of 1-dimethylaminonaphthalene-8-ketones: formation of a peri N–C bond or a hydrogen bond to the pi-electron density of a carbonyl group

Mercadal, N., Day, S. P., Jarmyn, A., Pitak, M. B., Coles, S. J., Wilson, C. , Rees, G. J., Hanna, J. V. and Wallis, J. D. (2014) O- vs. N-protonation of 1-dimethylaminonaphthalene-8-ketones: formation of a peri N–C bond or a hydrogen bond to the pi-electron density of a carbonyl group. CrystEngComm, 16(36), pp. 8363-8374. (doi: 10.1039/C4CE00981A)

Abstract

X-ray crystallography and solid-state NMR measurements show that protonation of a series of 1-dimethylaminonaphthalene-8-ketones leads either to O protonation with formation of a long N–C bond (1.637–1.669 Å) between peri groups, or to N protonation and formation of a hydrogen bond to the π surface of the carbonyl group, the latter occurring for the larger ketone groups (C([double bond, length as m-dash]O)R, R = t-butyl and phenyl). Solid state 15N MAS NMR studies clearly differentiate the two series, with the former yielding significantly more deshielded resonances. This is accurately corroborated by DFT calculation of the relevant chemical shift parameters. In the parent ketones X-ray crystallography shows that the nitrogen lone pair is directed towards the carbonyl group in all cases.

• Item Type: Articles
• Status: Published
• Refereed: Yes
• Glasgow Author(s) Enlighten ID: Wilson, Dr Claire
• Authors: Mercadal, N., Day, S. P., Jarmyn, A., Pitak, M. B., Coles, S. J., Wilson, C., Rees, G. J., Hanna, J. V., and Wallis, J. D.
• College/School: College of Science and Engineering > School of Chemistry
• Journal Name: CrystEngComm
• Publisher: Royal Society of Chemistry
• ISSN: 1466-8033
• Published Online: 15 July 2014
• Copyright Holders: Copyright © 2014 The Royal Society of Chemistry
• First Published: First published in CrystEngComm 16(36): 8363-8374
• Publisher Policy: Reproduced under a Creative Commons License