Proton‐transfer compounds with 4‐amino‐N‐(4,6‐dimethylpyrimidin‐2‐yl)benzenesulfonamide (sulfamethazine): the structures and hydrogen bonding in the salts with 5‐nitrosalicylic acid and picric acid
The structures of the anhydrous proton‐transfer compounds of the sulfa drug sulfamethazine with 5‐nitrosalicylic acid and picric acid, namely 2‐(4‐aminobenzenesulfonamido)‐4,6‐dimethylpyrimidinium 2‐hydroxy‐5‐nitrobenzoate, C12H15N4O2S+·C7H4NO4 −, (I), and 2‐(4‐aminobenzenesulfonamido)‐4,6‐dimethylpyrimidinium 2,4,6‐trinitrophenolate, C12H15N4O2S+·C6H2N3O7 −, (II), respectively, have been determined. In the asymmetric unit of (I), there are two independent but conformationally similar cation–anion heterodimer pairs which are formed through duplex intermolecular N+—H...Ocarboxylate and N—H...Ocarboxylate hydrogen‐bond pairs, giving a cyclic motif [graph set R 2 2(8)]. These heterodimers form separate and different non‐associated substructures through aniline N—H...O hydrogen bonds, one one‐dimensional, involving carboxylate O‐atom acceptors, the other two‐dimensional, involving both carboxylate and hydroxy O‐atom acceptors. The overall two‐dimensional structure is stabilized by π–π interactions between the pyrimidinium ring and the 5‐nitrosalicylate ring in both heterodimers [minimum ring‐centroid separation = 3.4580 (8) Å]. For picrate (II), the cation–anion interaction involves a slightly asymmetric chelating N—H...O R 2 1(6) hydrogen‐bonding association with the phenolate O atom, together with peripheral conjoint R 1 2(6) interactions between the same N—H groups and O atoms of the ortho‐related nitro groups. An inter‐unit amine N—H...Osulfone hydrogen bond gives one‐dimensional chains which extend along a and inter‐associate through π–π interactions between the pyrimidinium rings [centroid–centroid separation = 3.4752 (9) Å]. The two structures reported here now bring to a total of four the crystallographically characterized examples of proton‐transfer salts of sulfamethazine with strong organic acids.
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Document Type: Research Article
Affiliations: Science and Engineering Faculty, Queensland University of Technology, GPO Box 2434, Brisbane, Queensland 4001, Australia
Publication date: May 15, 2013