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

DOI: 10.1039/C4CE00981A

Authors: Nerea Mercadal (Nottingham Trent University) , Stephen P. Day (University of Warwick) , Andrew Jarmyn (Nottingham Trent University) , Mateusz Pitak (University of Southampton) , Simon Coles (University of Southampton) , Claire Wilson (Diamond Light Source) , Gregory J. Rees (University of Warwick) , John V. Hanna (University of Warwick) , John D. Wallis (Nottingham Trent University)
Co-authored by industrial partner: No

Type: Journal Paper
Journal: Crystengcomm , VOL 16 (36) , PAGES 10943-10958

State: Published (Approved)
Published: July 2014
Diamond Proposal Number(s): 8521

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.

Subject Areas: Chemistry


Instruments: I19-Small Molecule Single Crystal Diffraction

Added On: 18/09/2014 15:31

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