Abstract
The structures of the 1:1 co-crystalline adduct C8H6BrN3S·C7H5NO4, (I), and the salt C8H7BrN3S(+)·C7H3N2O7 (-), (II), obtained from the inter-action of 5-(4-bromo-phen-yl)-1,3,4-thia-diazol-2-amine with 4-nitro-benzoic acid and 3,5-di-nitro-salicylic acid, respectively, have been determined. The primary inter-species association in both (I) and (II) is through duplex R (2) 2(8) (N-H⋯O/O-H⋯O) or (N-H⋯O/N-H⋯O) hydrogen bonds, respectively, giving heterodimers. In (II), these are close to planar [the dihedral angles between the thia-diazole ring and the two phenyl rings are 2.1 (3) (intra) and 9.8 (2)° (inter)], while in (I) these angles are 22.11 (15) and 26.08 (18)°, respectively. In the crystal of (I), the heterodimers are extended into a chain along b through an amine N-H⋯Nthia-diazole hydrogen bond but in (II), a centrosymmetric cyclic hetero-tetra-mer structure is generated through N-H⋯O hydrogen bonds to phenol and nitro O-atom acceptors and features, together with the primary R (2) 2(8) inter-action, conjoined R (4) 6(12), R (2) 1(6) and S(6) ring motifs. Also present in (I) are π-π inter-actions between thia-diazole rings [minimum ring-centroid separation = 3.4624 (16) Å], as well as short Br⋯Onitro inter-actions in both (I) and (II) [3.296 (3) and 3.104 (3) Å, respectively].
Highlights
1,3,4-Thiadiazole (TZ) and its derivatives, the 2-amino-substituted analogues (ATZ), which are commonly phenyl-substituted at the 5-site of the thiadiazole ring, exhibit a broad range of biological activities (Jain et al, 2013). These 2-amino-1,3,4-thiadiazoles usually interact through duplex N—HÁ Á ÁN hydrogen bonds, giving a centrosymmetric cyclic R22(8) hydrogen-bonding homodimer motif, which may be discrete e.g. the 5-(3-fluorophenyl)-ATZ derivative (Wang et al, 2009) or more often is extended into a one-dimensional chain structure through the second 2-amino H-atom by an N—HÁ Á ÁN4thiadiazole hydrogen bond, e.g. in the 5-(4-bromophenyl)-ATZ derivative (Lynch, 2009a) and the 5(4-bromo-2-nitrophenyl)-ATZ derivative (Zhang et al, 2011)
With an interest in the formation of co-crystalline adducts as opposed to proton-transfer salt formation between Lewis bases and aromatic carboxylic acids, we have looked at some of these 5-phenyl-substituted ATZ analogues and have reported examples of both structure types: one-dimensional chain structures in the 1:1 adduct of 5-(4-methoxyphenyl)2-amino-1,3,4-thiadiazol-2-amine with 4-nitrobenzoic acid (Lynch, 2009b) and 5-(4-bromophenyl)-2-amino-1,3,4-thiadoi:10.1107/S1600536814021138
We report the structures of the 1:1 co-crystalline adduct, C8H6BrN3SÁC7H5NO4, (I), and the salt C8H7BrN3S+ÁC7H3N2O7À, (II), obtained from the interaction of BATZ with 4-nitrobenzoic acid (PNBA) and 3,5-dinitrosalicylic acid (DNSA), respectively
Summary
1,3,4-Thiadiazole (TZ) and its derivatives, the 2-amino-substituted analogues (ATZ), which are commonly phenyl-substituted at the 5-site of the thiadiazole ring, exhibit a broad range of biological activities (Jain et al, 2013). With an interest in the formation of co-crystalline adducts as opposed to proton-transfer salt formation between Lewis bases and aromatic carboxylic acids, we have looked at some of these 5-phenyl-substituted ATZ analogues and have reported examples of both structure types: one-dimensional chain structures in the 1:1 adduct of 5-(4-methoxyphenyl)2-amino-1,3,4-thiadiazol-2-amine with 4-nitrobenzoic acid (Lynch, 2009b) and 5-(4-bromophenyl)-2-amino-1,3,4-thiadoi:10.1107/S1600536814021138. 3,5-dinitrobenzoic acid (Smith & Lynch, 2013) In this salt structure, the carboxylate group gives the previously mentioned primary cyclic R22(8) association through carboxyl OÁ Á ÁH—N and amine N—HÁ Á ÁO hydrogen bonds but instead of forming the chain structure, a centrosymmetric heterotetramer is formed through a cyclic R24(8) hydrogen-bonding motif.
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