Crystal structures of the co-crystalline adduct 5-(4-bromophenyl)-1,3,4-thiadiazol-2-amine-4-nitrobenzoic acid (1/1) and the salt 2-amino-5-(4-bromophenyl)-1,3,4-thiadiazol-3-ium 2-carboxy-4,6-dinitrophenolate

Abstract

The structures of the 1:1 co-crystalline adduct C8H6BrN3S·C7H5NO4, (I), and the salt C8H7BrN3S+·C7H3N2O7 -, (II), obtained from the interaction of 5-(4-bromophenyl)-1,3,4-thiadiazol-2-amine with 4-nitrobenzoic acid and 3,5-dinitrosalicylic 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 thiadiazole 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⋯Nthiadiazole hydrogen bond but in (II), a centrosymmetric cyclic heterotetramer 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) interaction, conjoined R 4/6(12), R 2/1(6) and S(6) ring motifs. Also present in (I) are π-π interactions between thiadiazole rings [minimum ring-centroid separation = 3.4624 (16) Å], as well as short Br⋯Onitro interactions in both (I) and (II) [3.296 (3) and 3.104 (3) Å, respectively].