(Adipato-κ2 O,O′)diaqua[bis(pyridin-2-yl-κN)amine]cobalt(II) trihydrate

In the monomeric title complex, [Co(C6H8O4)(C10H9N3)(H2O)2]·3H2O, the distorted octahedral CoN2O4 coordination environment comprises two N-atom donors from the bidentate dipyridyldiamine ligand, two O-atom donors from one of the carboxylate groups of the bidentate chelating adipate ligand and two water molecules. In addition, there are three solvent water molecules which are involved in both intra- and inter-unit O—H⋯O hydrogen-bonding interactions, which together with an amine–water N—H⋯O hydrogen bond produce a three-dimensional framework.

In the monomeric title complex, [Co(C 6 H 8 O 4 )(C 10 H 9 N 3 )-(H 2 O) 2 ]Á3H 2 O, the distorted octahedral CoN 2 O 4 coordination environment comprises two N-atom donors from the bidentate dipyridyldiamine ligand, two O-atom donors from one of the carboxylate groups of the bidentate chelating adipate ligand and two water molecules. In addition, there are three solvent water molecules which are involved in both intra-and inter-unit O-HÁ Á ÁO hydrogen-bonding interactions, which together with an amine-water N-HÁ Á ÁO hydrogen bond produce a three-dimensional framework.
Given the rich coordination chemistry and the flexibility of these anionic ligands, we are interested in using them in combination with other chelating co-ligands to explore their structural features and properties in the large field of molecular materials. This led us to the synthesis of the parent coordination compound, the title complex [Co(dpa)(adip) (H 2 O) 2 ]. 3H 2 O, (where dpa is 2,2′-dipyridylamine and adip is the adipate dianion), and the structure is described herein.
In this monomeric complex, the distorted octahedral MN 2 O 4 coordination sphere comprises two N-donors from the bidentate chelate dpa ligand, two carboxyl O-donors (O1, O2) from one of the carboxyl groups of the adipate ligand and two water molecules (O5, O6). In addition, there are three water molecules of solvation (O7-O9) (Fig. 1). The (N,N′) interaction is essentially symmetric [Co-N, 2.0596 (10), 2.0781 (9) Å] (Table 1)  In the crystal, both the coordinated water molecules and the solvent water molecules are involved in both intra-and inter-unit O-H···O hydrogen-bonding interactions. The amine N-atom of the dpa ligand is also hydrogen-bonded to a water molecule (O9) ( Table 2), giving an overall three-dimensional framework structure (Fig. 2).

Experimental
All reagents were purchased from commercial sources and used as received. Under aerobic conditions, an ethanolic solution of 2,2′-dipyridylamine (0.017 g, 5 ml) was added, with stirring at room temperature to an ethanolic solution of CoCl 2 .6H 2 O (0.024 g, 5 ml), resulting in a pink suspension. Adipic acid was dissolved in water (0.015 g, 10 ml) and added quickly to the mixture. The final solution was filtered and the filtrate allowed to evaporate in air for two weeks, giving brown crystals of the title compound suitable for X-ray diffraction analysis.

Refinement
All H-atoms potentially involved in hydrogen-bonding were located from a difference-Fourier and both positional and isotropic displacement parameters were refined. Other H-atoms were placed in calculated positions with C-H(aromatic) = 0.93 Å or C-H(methylene) = 0.97 Å and with U iso (H) = 1.2U eq (C). Several reflections (8)

Special details
Geometry. Bond distances, angles etc. have been calculated using the rounded fractional coordinates. All su's are estimated from the variances of the (full) variance-covariance matrix. The cell e.s.d.'s are taken into account in the estimation of distances, angles and torsion angles 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 > 2σ(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