Tetraaquabis(3,5-di-4-pyridyl-1,2,4-triazolato-κN)cobalt(II) dihydrate

The CoII atom in the title compound, [Co(C12H8N5)2(H2O)4]·2H2O, lies on a center of inversion and is bonded to two N-heterocycles and to four water molecules in a slightly distorted octahedral coordination. The coordinated and lattice water molecules interact with the N-heterocycles through O—H⋯N hydrogen bonds, generating a three-dimensional supramolecular architecture.

The Co II atom in the title compound, [Co(C 12 H 8 N 5 ) 2 (H 2 O) 4 ]Á-2H 2 O, lies on a center of inversion and is bonded to two Nheterocycles and to four water molecules in a slightly distorted octahedral coordination. The coordinated and lattice water molecules interact with the N-heterocycles through O-HÁ Á ÁN hydrogen bonds, generating a three-dimensional supramolecular architecture.
In this work, we synthesized a new compound [Co(L) 2 (H 2 O) 4 ](H 2 O) 2 (I) (L = 3,5-di(4-pyridine)-1,2,4-triazole). 1 is composed of one cobalt(II) cation, two L ligand, four coordinated and two lattice water molecules. The cobalt(II) cation is six-coordinated in the octahedral geometry. The equatorial site of Cobalt cation is occupied by four aqua molecules while the axial site is occupied by two nitrogen atoms of two mono-dentate L ligands. The mono-dentate coordination mode of L is different from previously reported di-, tri-or tetra-dentate coordination modes of L.
strong N-H···O hydrogen bonds generated from water molecules and nitrogen atoms of pyridine or triazole groups are also observed rusulting in the three-dimensional supramolecular network (Table 2). π-π stacking interactions between two neighboring triazole groups further consolidating the architecture centroid-centroid distance 3.677 (4) Å] Perspective drawing with the atomic numbering scheme is illustrated in figure 1. Selected geometric parameters (Å, °) for 1 are listed in table 1. Selected hydrogen-bonding geometric parameters (Å, °) for 1 are listed in table 2. The trinuclear water clusters, corresponding N-H···O hydrogen bonds and π-π stacking are shown in figure 2. The three-dimensional supramolecular packing architecture of (I) is shown in figure 3.

Experimental
The ligand was prepared according to the previous literature (Basu & Dutta, (1964) The carbon-bound H atoms were positioned geometrically and were allowed to ride on their parent C atoms. The water H atoms were located from a difference density map and were refined with distance restraints of O-H = 0.85±0.01 Å.
Figures Fig. 1. The molecular structure and atom-labeling scheme of (I).