Tetraaqua{1-[(1H-1,2,3-benzotriazol-1-yl)methyl]-1H-1,2,4-triazole}sulfatozinc(II) dihydrate

In the title complex, [Zn(SO4)(C9H8N6)(H2O)4]·2H2O, the ZnII ion is six-coordinated by one N atom from a 1-[(1H-1,2,3-benzotriazol-1-yl)methyl]-1H-1,2,4-triazole ligand and five O atoms from one monodentate sulfate anion and four water molecules in a distorted octahedral geometry. The sulfate tetrahedron is rotationally disordered over two positions in a 0.618 (19):0.382 (19) ratio. In the crystal, adjacent molecules are linked through O—H⋯O and O—H⋯N hydrogen bonds involving the cation, the anion, and the coordinated and uncoordinated water molecules into a three-dimensional network.

In the title complex, [Zn(SO 4 )(C 9 H 8 N 6 )(H 2 O) 4 ]Á2H 2 O, the Zn II ion is six-coordinated by one N atom from a 1-[(1H-1,2,3benzotriazol-1-yl)methyl]-1H-1,2,4-triazole ligand and five O atoms from one monodentate sulfate anion and four water molecules in a distorted octahedral geometry. The sulfate tetrahedron is rotationally disordered over two positions in a 0.618 (19):0.382 (19) ratio. In the crystal, adjacent molecules are linked through O-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds involving the cation, the anion, and the coordinated and uncoordinated water molecules into a three-dimensional network.

Comment
Up to now, numerous complexes with one-, two-and three-dimensional structure motifs based on symmetrical N-heterocyclic ligands have been synthesized and reported (Fan & Hanson, 2005;Zhao et al., 2007), whereas complexes based on unsymmetrical N-heterocyclic ligands are relatively scarce. Focused on complexes with Zn II , this ion is able to coordinate to different donors simultaneously and the final products can exhibit promising luminescent properties (Lin et al., 2008;Liu et al., 2010). In this work, through the reaction of 1-((benzotriazol-1-yl)methyl)-1-H-1,2,4-triazole (bmt) with zinc sulfate at room temperature, we obtained the title complex [Zn(bmt)(SO 4 )(H 2 O) 4 ](H 2 O) 2 , which is reported here.
As shown in Figure 1, the Zn II ion displays a distorted octahedral coordination defined by five oxygen atoms from four water molecules and one monodentate sulfate anion and by one nitrogen atom from the bmt ligand. Atoms O1, O5, O6, O8 and Zn1 are nearly co-planar (the mean deviation from the plane is 0.0258 Å), and atoms O7 and N1 are located in the apical positions. The SO 4 tetrahedron is rotationally disordered about its S-O axis passing through O1 and S1 atoms.

O-H···O and O-H···N hydrogen bonds including coordinated and uncoordinated water molecules, the cations and anions
consolidate the crystal packing ( Figure 2).

Experimental
The ligand 1-((benzotriazol-1-yl)methyl)-1-H-1,2,4-triazole (0.1 mmol) in methanol (5 ml) was added dropwise to an aqueous solution (2 ml) of zinc sulfate (0.1 mmol). The resulting solution was allowed to stand at room temperature. After three weeks, colorless crystals with good quality were obtained from the filtrate and were dried in air.