Bis(5-phenyl-1H-1,2,4-triazol-3-yl) disulfide dihydrate

A crystallographic twofold axis passing through the centre of the disulfide linkage in the title compound, C16H12N6S2·2H2O, results in one-half of the molecule and one uncoordinated water molecule described in the asymmetric unit. In the molecule, the mean planes of the benzene and triazole rings are close to being coplanar and are separated by a dihedral angle of 2.08 (15)°. The triazole rings are twisted by a dihedral angle of 37.67 (6)° from the disulfide linkage. The crystal packing is stabilized by intermolecular N—H⋯O and O—H⋯N hydrogen bonds with the water molecules, forming a three-dimensional supramolecular network.

A crystallographic twofold axis passing through the centre of the disulfide linkage in the title compound, C 16 H 12 N 6 S 2 Á2H 2 O, results in one-half of the molecule and one uncoordinated water molecule described in the asymmetric unit. In the molecule, the mean planes of the benzene and triazole rings are close to being coplanar and are separated by a dihedral angle of 2.08 (15) . The triazole rings are twisted by a dihedral angle of 37.67 (6) from the disulfide linkage. The crystal packing is stabilized by intermolecular N-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds with the water molecules, forming a three-dimensional supramolecular network.

Comment
In the past few years, 1,2,4-triazole and its derivatives have attracted increasing attention as an N-heterocyclic aromatic ligand, since they can combine both imidazoles and pyrazoles in their coordination geometry. In addition, metal-triazolate frameworks can exhibit special luminescent, magnetic and favourable gas-adsorption abilities (Ouellette et al., 2007;Zhang et al., 2005;Zhu et al., 2009). 1,2,4-triazole based thiols and disulfides are important 1,2,4-triazole derivatives, and may exhibit a more diverse coordination geometry by combining heterocyclic nitrogen and sulfur donor atoms, and therefore affect biological activity behaviour. However, only one example of a crystallographic study on organic 1,2,4-triazole based disulfide compounds is found in the literature (Jiang et al. 2007). Although the synthesis of the compound 1,2-bis(5-phenyl-1H-1,2,4-triazol-3-yl)disulfide has been reported by El-Wareth & Sarhan (2000), no crystallographic study has been reported on the ligand and related metal coordination compounds. We reported herein another synthetic method and the crystal structure of the title compound.
A crystallographic 2-fold axis passing through the centroid of the disulfide linkage in the title compound, C 16 H 12 N 6 S 2 .2H 2 O, results in one-half of the molecule and one uncoordinated water molecule described in the asymmetric unit (Fig. 1). In the molecule, the mean planes of the benzene and triazole rings are close to coplanar, separated by a dihedral angle of 2.08 (15)°. The triazole rings are twisted by a dihedral angle of 37.67 (6)° from the disulfide linkage.
Crystal packing is stabilized by intermolecular N-H···O and O-H···N hydrogen bonds with the water molecules forming a three-dimensional supramolecular network (Fig. 2).

Experimental
A mixture of iron dichloride tetrahydrate (40 mg, 0.2 mmol), 3-phenyl-1H-1,2,4-triazole-5(4H)-thione (35 mg, 0.2 mmol), 8 ml methanol and 4 ml acetonitrile was stirred for 10 min, then filtered and allowed to stand at room temperature for about two weeks. Yellow polyhedron crystals suitable for X-ray diffraction were obtained.    as those based on F, and R-factors based on ALL data will be even larger.