title: Structure of a 4-nitroso-5-aminopyrazole and its salts: tautomerism, protonation, and E/Z isomerism.
abstract: The structures of 1-benzyl-4-nitroso-5-aminopyrazole (1) and its hydrochloride (1H+) have been determined in the solid state and in solution in DMSO, methanol, and ethanol. The free base exists in solution as a mixture of amino/nitroso tautomers 2a and 2b rather than in the imino/oxime tautomers 3. The conjugated cation 1H+ results from the protonation of the nitroso group. X-ray crystallography showed that both amino hydrogen atoms of 2a form NH...O=N hydrogen bonds: one is intramolecular, the other links adjacent molecules in an infinite chain.
authors: Institut für Nuklearchemie (INC), Forschungszentrum Juelich, D-52425 Juelich, Germany. m.holschbach@fz-juelich.de
authors: Marcus H
authors: MH
authors: Holschbach
authors: Dionisia
authors: D
authors: Sanz
authors: Rosa M
authors: RM
authors: Claramunt
authors: Lourdes
authors: L
authors: Infantes
authors: Sam
authors: S
authors: Motherwell
authors: Paul R
authors: PR
authors: Raithby
authors: María Luisa
authors: ML
authors: Jimeno
authors: David
authors: D
authors: Herrero
authors: Ibon
authors: I
authors: Alkorta
authors: Nadine
authors: N
authors: Jagerovic
authors: José
authors: J
authors: Elguero