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

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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. ORCID: 0000-0001-7259-8783, 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. ISSN 1466-8033

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Official URL: http://dx.doi.org/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(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:

Journal article

Publication Title:

CrystEngComm

Creators:

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.

Publisher:

Royal Society of Chemistry

Place of Publication:

Cambridge

Date:

2014