Bis(2,2′-bipyridyl dioxide-κ2 N,N′)bis(tricyanomethanido)cobalt(II) dihydrate

In the title compound, [Co(C4N3)2(C10H8N2O2)]·2H2O, a novel tricyanomethanide complex, the CoII atom is located on an inversion center and has a distorted octahedral coordination with two 2,2′-bipyridyl dioxide (dpdo) molecules and two trans tricyanomethanide (tcm) anions. The equatorial plane is formed by the four O atoms of the two chelating dpdo ligands, with one N atom of each of the two tcm ligands occupying an apical position. There is a disordered solvent water molecule in the asymmetric unit (occupancy ratio 0.63:0.37). These water molecules result in the formation of O—H⋯O and O—H⋯N hydrogen bonds, building a layer parallel to (100). The layers are linked by C—H⋯N hydrogen-bonding interactions, leading to a three-dimensional network.

In the title compound, [Co(C 4 N 3 ) 2 (C 10 H 8 N 2 O 2 )]Á2H 2 O, a novel tricyanomethanide complex, the Co II atom is located on an inversion center and has a distorted octahedral coordination with two 2,2 0 -bipyridyl dioxide (dpdo) molecules and two trans tricyanomethanide (tcm) anions. The equatorial plane is formed by the four O atoms of the two chelating dpdo ligands, with one N atom of each of the two tcm ligands occupying an apical position. There is a disordered solvent water molecule in the asymmetric unit (occupancy ratio 0.63:0.37). These water molecules result in the formation of O-HÁ Á ÁO and O-HÁ Á ÁN hydrogen bonds, building a layer parallel to (100). The layers are linked by C-HÁ Á ÁN hydrogen-bonding interactions, leading to a three-dimensional network.
Recently, several copper tcm complexes with nitrogen-containing heterocyclic co-ligands has been characterized (Yuste et al., 2008(Yuste et al., , 2007. On the other hand, 2,2'-dipyridyl N,N'-dioxide (dpdo) is a new co-ligand and has two potential oxygen donor atoms, however, few tcm complex with dpdo co-ligand has been reported (Luo et al., 2009). During our systematic investigation of the nature of dpdo co-ligand on the structures and properties of tcm complexes, we obtained a new tcm complex Co(dpdo) 2 (C 4 N 3 ) 2 (H 2 O) 2 (I), we herein report the synthesis and crystal structure of the complex.
In the title compound, the cobalt atom, located on an inversion center, has a distorted octahedral geometry with two dpdo molecules and two trans tricyanomethanide. The equatorial plane being formed by the four O atoms of the two chelating dpdo ligands whereas one N atom of each tcm ligands occupying the apical positions ( Fig. 1).
Interestingly, two solvate water molecules are observed and the situation is different from the similar manganese complex reported in which no water molecules were found (Luo et al., 2009). In the title compound, these water molecules result in the formation of O-H···O and O-H···N hydrogen bonds building a layer parallel to the (1 0 0) plane (Table 1, Fig. 2).
Furthermore, C-H···N hydrogen interactions (Table 1)  Each tricyanomethanide moiety is almost planar. Bond distances and bond angles within the anions are in good agreement with those found in other tricyanomethanide complexes (Hoshino et al., 1999;Batten et al., 1999).

Experimental
A 5 ml warm acetonitrile solution of 2,2'-dipyridyl N,N'-dioxide (0.10 mmol, 18.82 mg) and a 2 ml aqueous red solution of cobalt nitrate (0.10 mmol, 29.10 mg) were mixed and stirred for 5 min s, the mixed solution was orange. To the mixture supplementary materials sup-2 was added a 3 ml acetonitrile-water solution (CH 3 CN:H 2 O = 2:1, V:V) of potassium tricyanomethanide (0.20 mmol, 25.83 mg). After stirred for another 5 min s, the orange solution was filtered and the filtrate was slowly evaporated in air. After two weeks, orange block crystals of I were isolated in 34% yield.

Refinement
All H atoms attached to C atoms were fixed geometrically and treated as riding with C-H = 0.93 Å with U iso (H) = 1.2U eq (C). H atoms of water molecule were located in difference Fourier maps and included in the subsequent refinement using restraints (O-H= 0.85 (1)Å and H···H= 1.39 (2)Å) with U iso (H) = 1.5U eq (O). In the last stage of refinement, they were treated as riding on the O atom.
The water molecules appear to be disorered over two positions with occupancy factors roughly in the ratio 2/1. The occupancy factors were determined using a constrained refinement with the sum of the occupancy fixed to 1.

Special details
Geometry. All esds (except the esd in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell esds are taken into account individually in the estimation of esds in distances, angles and torsion angles; correlations between esds in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell esds is used for estimating esds involving l.s. planes.
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 Rfactors(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.

Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å 2 )
x y z U iso */U eq Occ. (