Different acid–base behaviour of a pyrazole and an isoxazole with organic acids: crystal and mol­ecular structures of the salt 3-(4-fluoro­phen­yl)-1H-pyrazolium 2,4,6-tri­nitro­phenolate and of the cocrystal 4-amino-N-(3,4-di­methyl-1,2-oxazol-5-yl)benzene­sulfonamide–3,5-di­nitro­benzoic acid (1/1)

Girisha, M. and Yathirajan, H. S. and Jasinski, Jerry P. and Glidewell, Christopher (2016) Different acid–base behaviour of a pyrazole and an isoxazole with organic acids: crystal and mol­ecular structures of the salt 3-(4-fluoro­phen­yl)-1H-pyrazolium 2,4,6-tri­nitro­phenolate and of the cocrystal 4-amino-N-(3,4-di­methyl-1,2-oxazol-5-yl)benzene­sulfonamide–3,5-di­nitro­benzoic acid (1/1). Acta Crystallographica Section C, 72 (8). pp. 612-618. ISSN 2053-2296

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Official URL: https://doi.org/10.1107/S2053229616010494

Abstract

Pyrazole and isoxazole rings differ only in the notional replacement of a potential hydrogen-bond-donor NH unit in pyrazole by a potential hydrogen-bond-acceptor O atom in isoxazole. It is thus of inter\-est to compare the hydro\-gen-bonding characteristics of these rings. (4-Fluoro\-phen\-yl)pyrazole undergoes protonation in the presence of 2,4,6-tri\-nitro\-phenol to yield the salt 3-(4-fluoro\-phen\-yl)-1\it H-pyrazolium 2,4,6-tri\-nitro\-phenolate, C\sb 9H\sb 8FN\sb 2\sp +⋅C\sb 6H\sb 2N\sb 3O\sb 7\sp -}}, (I), whereas there is no proton transfer between 4-amino-\it N-(3,4-dimethyl-1,2-oxazol-5-yl)benzene\-sulfonamide and 3,5-di\-nitro\-benzoic acid, whose reaction gives the 1:1 cocrystal, C\sb 11H\sb 13N\sb 3O\sb 3S⋅C\sb 7H\sb 4N\sb 2O\sb 6, (II). The bond lengths in salt (I) provide evidence for aromatic-type delocalization in the pyrazolium ring and for extensive delocalization of the negative charge into the ring of the tri\-nitro\-phenolate anion. The O atoms of one of the nitro groups in the tri\-nitro\-phenolate anion are disordered over two sets of atomic sites having occupancies of 0.571(6) and 0.429(6), but all of the other substituents on the carbocyclic rings are fully ordered. The ions in salt (I) are linked by an extensive series of N—-H⋅sO hydrogen bonds to form a three-dimensional framework structure, and in cocrystal (II), the mol\-ecular components are linked by a combination of O—-H⋅sN and N—-H⋅sO hydrogen bonds to form complex bilayers. Comparisons are made with some related compounds.

Item Type: Article
Uncontrolled Keywords: synthesis, acid-base behaviour, crystal structure, molecular conformations, hydrogen bonding
Subjects: C Chemical Science > Chemistry
Divisions: Department of > Chemistry
Depositing User: manjula User
Date Deposited: 20 Jun 2019 05:54
Last Modified: 14 Nov 2019 10:09
URI: http://eprints.uni-mysore.ac.in/id/eprint/3462

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