The interaction of 2,6-pyridinedicarbonyl dichloride (2,6-Py(COCl)2) with cobalt(II) nitrate in a solvent mixture of dioxane-dimethylacetamide in the presence of diphenylglyoxime, a new compound was obtained. The structure of this compound was investigated by XRD and shown the conversion of 2,6-Py(COCl)2 to a dianion of dipicolinic acid, (2,6-Py(COO)2)2-, during the reaction in situ. The interaction of dipicolinic acid with cobalt(II) nitrate in the same medium in the absence of diphenylglyoxime, but in the presence of ammonium hydroxide resulted in similar compound of Co(III) with formula NH4[Co(2,6-Py(COO)2)2] (1), that crystallizes in tetragonal I41/a space group with a=7.1181(8) Å, c=27.976(1) Å, V=1417.5(2) Å3. These crystals comprise the NH4+ cationsand [CoIII(2,6-Py(COO)2)2]- complex anions (Fig. 1). The bideprotonated dipicolinic ligand (2,6-Py(COO)2)2-is three-dentate and coordinate to cobalt(III) by ONO donor atoms forming two fused metallocycles.Thus, the coordination polyhedron of metal in 1 is provided by NO2 donor atoms belong two organic ligand that form octahedral surrounding with S4 molecular symmetry. The interatomic distances Co(1)–N(1) and Co(1)–O(1) in coordination polyhedron are 1.844(3) and 1.926(2)Å, respectively. The interaction of cobalt(II) nitrate and dipicolinic acid in methanol in the presence of dioxane and dimethylacetamide and changing the order of mixing of the components led to the formation the of Co(II) compound with composition (NH4)2[Co(2,6-Py(COO)2)2]·2H2O (2). This compound has been studied by X-ray single crystal method and has been established that it crystallizes in triclinic P-1 space group with a=10.779(1) Å, b=13.480(1) Å, c=14.506(2) Å, a=64.649(10)°, b=78.882(11)°, y=88.992(8)°, V=1864.0(4) Å3. The structure of 2 reveals [NH4]+ cations, [CoII(2,6-Py(COO)2)2]2- anionic complex, and solvate water molecules (Fig. 2). In 2 the organic ligand is also tridentate, double deprotonated and coordinates to cobalt(II) through the ONO donor atoms as in 1. The octahedral coordination polyhedron of metal in 2 is similar by 1. The interatomic distances Co–N and Co–O in two symmetry independent coordination anions are in ranges 2.025(3) – 2.032(3) and 2.140(3) – 2.222(3) Å, respectively.Fig. 1. The structure of 1.Fig. 2. The structure of symmetry independent compound 2.The cations and anions in 1 are involved in N–H···O hydrogen bonds, and in 2 the components interact by hydrogen bonds N–H···O, N–H···O(w), O(w)–H···O and O(w)–H···O(w).