Issue 6, 2007

The structure of fluorinated indazoles: the effect of the replacement of a H by a F atom on the supramolecular structure of NH-indazoles

Abstract

The structures of three NH-indazoles (3-methyl, 3-trifluoromethyl and 3-trifluoromethyl-4,5,6,7-tetrafluoroindazoles) have been determined by X-ray crystallography. These three compounds, together with 3-methyl-4,5,6,7-tetrafluoroindazole, whose X-ray structure could not be determined, have been studied using multinuclear magnetic resonance spectroscopy, including solid-state CPMAS. They all are 1H-tautomers. In the crystal, 3-methyl-1H-indazole forms hydrogen bonded dimers, whereas 3-trifluoromethyl-1H-indazole and 3-trifluoromethyl-4,5,6,7-tetrafluoro-1H-indazole crystallize as catemers. These catemers are chiral space group P32. They are the first examples of indazoles crystallizing in the form of helices of three-fold screw axis. Attempts at rationalizing this behavior on the basis of supramolecular interactions (hydrogen bonds and aromatic interactions) and GIAO calculations are discussed.

Graphical abstract: The structure of fluorinated indazoles: the effect of the replacement of a H by a F atom on the supramolecular structure of NH-indazoles

Supplementary files

Article information

Article type
Paper
Submitted
11 Dec 2006
Accepted
13 Mar 2007
First published
10 Apr 2007

New J. Chem., 2007,31, 936-946

The structure of fluorinated indazoles: the effect of the replacement of a H by a F atom on the supramolecular structure of NH-indazoles

J. Teichert, P. Oulié, K. Jacob, L. Vendier, M. Etienne, R. M. Claramunt, C. López, C. Pérez Medina, I. Alkorta and J. Elguero, New J. Chem., 2007, 31, 936 DOI: 10.1039/B617988F

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