Aminopyrazoles and their conjugated acids. An X-ray study of 3,5-dimethyl-4-aminopyrazole and the Picrate of 3(5)-aminopyrazole |
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Authors: | Lourdes Infantes Concepcin Foces-Foces Rosa María Claramunt Concepcin Lpez Jos Eiguero |
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Institution: | Lourdes Infantes,Concepción Foces-Foces,Rosa María Claramunt,Concepción López,José Eiguero |
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Abstract: | The crystal structure determination of 3,5-dimethyl-4-aminopyrazole ( 3 ) and of 3(5)-aminopyrazolium picrate salt ( 5a ) have been undertaken. The packing in 3 is characterized by the formation of sheets in which the N-H of the pyrazole and one H atom of the amino group are involved. The remaining HB donor interconnects sheets. In 5a , the anions and the cations are linked by a two-dimensional network of hydrogen bonds in the ab plane. Each N-H and C-H in the cation are involved in hydrogen interactions with the O atoms of the anion. Ab initio molecular orbital methods at the HF and B3LYP levels using a 6–31G** basis set have been carried out to compare the relative stability of the tautomeric forms of the 3(5)-aminopyrazolium and 4-aminopyrazolium cations. |
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