catena-Poly[[bis(4-methylpyridine-κN)cobalt(II)]-di-μ-dicyanamido-κ2 N 1:N 5]

Cobalt(II) nitrate hexahydrate and sodium dicyanamide self-assembled in dimethylformamide (DMF) and 4-methylpyridine solutions to form the title compound, [Co(C2N3)2(C6H7N)2]n. The Co2+ ion lies on an inversion center and adopts an octahedral coordination geometry in which four N atoms from four different dicyanamide ligands lie in the equatorial plane and two 4-methylpyridine N atoms occupy the axial positions. The CoII atoms are connected by two bridging dicyanamide ligands, resulting in a chain parallel to the c axis. The chains are connected into a three-dimensional network by C—H⋯N hydrogen bonds.


Related literature
The design and syntheses of metal-organic compounds has attracted great attention not only as a result of their intriguing architectures and topologies (Eddaoudi et al., 2001), but also because of their potential applications (Banerjee et al., 2008).
Data collection: CrystalClear (Rigaku, 2008); cell refinement: CrystalClear; data reduction: CrystalClear; program(s) used to solve structure: SHELXTL (Sheldrick, 2008); program(s) used to refine structure: SHELXTL; molecular graphics: SHELXTL; software used to prepare material for publication: SHELXTL. The design and syntheses of metal-organic compounds have attracted great attention in recent years because of not only their intriguing architectures and topologies (Eddaoudi et al., 2001) but also their potential applications (Banerjee et al., 2008). The title compound {Co[N(CN) 2 ] 2 (NC 6 H 7 ) 2 } n is constructed by the flexible dicyanamide bridging ligands through diffusion reaction.
As illustrated in Fig. 1, Co 2+ ion lies on an inversion center and adopts an octahedral coordination geometry, where four N atoms from four different dicyanamide ligands lie in the equatorial plane and two 4-methylpyridine N atoms occupy the axial positions. The Co atoms are connected by two dicyanamide ligands, resulting in a neutral chain along the c-axis.
In the crystal, the chains are linked by C-H···N hydrogen bonds (Table 1) into a three-dimensional network.

Experimental
Co(NO 3 ) 2 ?6H 2 O (116.6 mg, 0.4 mmol) was added into 1 ml dmf with thorough stir for 5 minutes. After filtration, the purple filtrate was carefully laid on the surface with the solution of NaN(CN) 2 (89.1 mg, 1 mmol) in 1 ml dmf, 1 ml 4methylpyridine and 5 ml i-PrOH. Pink block crystals were obtained after two weeks.

Refinement
H atoms were positioned geometrically and refined with riding model, with U iso = 1.5U eq and 1.2U eq for methyl and pyridyl H atoms, respectively. The C-H bonds are 0.96 Å in methyl and 0.93 Å in pyridyl.

catena-Poly[[bis(4-methylpyridine-κN)cobalt(II)]-di-µ-dicyanamido-κ 2 N 1 :N 5 ]
Crystal data Special details Geometry. All e.s.d.'s (except the e.s.d. in the dihedral angle between two l.s. planes) are estimated using the full covariance matrix. The cell e.s.d.'s are taken into account individually in the estimation of e.s.d.'s in distances, angles and torsion angles; correlations between e.s.d.'s in cell parameters are only used when they are defined by crystal symmetry. An approximate (isotropic) treatment of cell e.s.d.'s is used for estimating e.s.d.'s 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 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.

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