Diaquabis[2,6-bis(4H-1,2,4-triazol-4-yl)pyridine-κN 2]bis(selenocyanato-κN)cobalt(II)

In the title compound, [Co(NCSe)2(C9H7N7)2(H2O)2], the Co2+ cation is coordinated by two selenocyanate anions, two 2,6-bis(4H-1,2,4-triazol-4-yl)pyridine ligands and two water molecules within a slightly distorted N4O2 octahedron. The asymmetric unit consists of one Co2+ cation, which is located on a center of inversion, as well as one selenocyanate anion, one 2,6-bis(4H-1,2,4-triazol-4-yl)pyridine ligand and one water molecule in general positions. Intermolecular O—H⋯N hydrogen bonds join the complex molecules into layers parallel to the bc plane. The layers are linked by C—H⋯N and C—H⋯Se hydrogen bonds into a three-dimensional supramolecular architecture.


Related literature
For general background to this work, see: Liu et al. (2007). Previous research on compounds with Co(II) as cation have found a slow relaxation of the magnetization, see : Boeckmann & Nä ther (2010, 2011, 2012. For related structures, see: Du et al. (2009);Yang et al. (2008).

Yuan-Yuan Liu and Pan Yang Comment
Previously we have reported on the a series of novel zinc(II) and cadmium(II) compounds based on 2,6-di-(1,2,4triazole-4-yl)pyridine (Liu et al., 2007). On the other hand, dependent on the nature of the metal cation, anti-or ferromagnetic ordering is observed and for the compounds with Co(II) as cation preivous resrarch have found a slow relaxation of the magnetization (Boeckmann & Näther 2010, 2011, 2012. To investigate the influence of the co-ligand on the magnetic properties for the compounds with Co(II), we tried to prepare cobalt(II) compounds based on 2,6-di-(1,2,4triazole-4-yl)pyridine, which resulted in the formation of the title compound in which the neutral ligands are only terminal N-coordinated. This compound was characterized only by single-crystal X-ray diffraction. In the crystal structure the cobalt(II) cations are coordinated by four nitrogen atoms of two terminal N-bonded seleno-cyanato anions and two terminal bonded 2,6-di-(1,2,4-triazole-4-yl)pyridine co-ligands as well as two water molecules into discrete complexes (Fig. 1). The coordination polyhedron of the Co cations can be described as a slightly distorted octahedron with the Co cation located on a centre of inversion. The discrete cobalt complexes are bridged by intermolecular O-H···N, C-H···N and C-H···Se hydrogen bonds (Yang et al., 2008;Du et al., 2009), wich assemble (I) into a threedimensional supra-molecular architecture( Fig. 2 and Table 1).
Perspective drawing with the atomic numbering scheme is illustrated in figure 1. Selected geometric parameters (Å, °) for (I) are listed in table 1. Selected hydrogen-bonding geometric parameters (Å, °) for (I) are listed in table 2. The twodimensional supramolecular framework of (I) is shown in Figure 2.

Refinement
The water H atoms were located in a Fourier difference map and refined subject to an O-H restraint 0.88 (1) Å and an H···H restraint of 1.42 (2) Å. Other H atoms were allowed to ride on their parent atoms with C-H distances of 0.93 Å (U iso (H) = 1.2Ueq(C)). All of the non-hydrogen atoms were refined anisotropically.. (Sheldrick, 2008); molecular graphics: SHELXTL and DIAMOND (Brandenburg, 1999); software used to prepare material for publication: publCIF (Westrip, 2010).

Figure 1
The structure of the title complex, showing 50% probability displacement ellipsoids and the atom-numbering schemes.
Atoms of the inversion-related half-complex have symmetry code: (2 -x, y, 1/2 -z).   Refinement. Refinement of F 2 against ALL reflections. The weighted R-factor wR and goodness of fit S are based on F 2 , conventional R-factors R are based on F, with F set to zero for negative F 2 . The threshold expression of F 2 > σ(F 2 ) is used only for calculating R-factors(gt) etc. and is not relevant to the choice of reflections for refinement. R-factors based on F 2 are statistically about twice as large as those based on F, and R-factors based on ALL data will be even larger.