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Structure and tautomerism of 4-bromo substituted 1H-pyrazoles |
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| Authors: | Swiatoslav Trofimenko,Glenn P.A. Yap,Rosa M. Claramunt,M. Á ngeles Garcí a,Ibon Alkorta |
| Affiliation: | a Department of Chemistry and Biochemistry, University of Delaware, Newark, DE 19716, USA b Departamento de Química Orgánica y Bioorgánica, Facultad de Ciencias, UNED, Senda del Rey, 9, E-28050 Madrid, Spain c Instituto de Química Médica, CSIC, Juan de la Cierva, 3, E-28006 Madrid, Spain |
| Abstract: | The tautomerism in the solid state and in solution of five 4-bromo-1H-pyrazoles has been studied by multinuclear magnetic resonance spectroscopy and, for one of them, by X-ray crystallography (3,4-dibromo-5-phenyl-1H-pyrazole). When there is a bromine atom at position 3(5), in all cases, the tautomer present in the solid state is the 3-bromo one. In solution, the same tautomer is the major one. DFT calculations justify the predominance of 3-bromo tautomers over 5-bromo ones and provide some useful chemical shifts obtained through GIAO calculations. |
| Keywords: | Bromopyrazoles Tautomerism: X-ray structure Solid-state NMR DFT calculations GIAO calculations |
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