Crystal structure of tetraaqua-[(1-(carboxymethyl)-1 H -pyrazole-3-carboxylato- κ 2 N , O )cobalt(II)], C 6 H 12 CoN 2 O 8

C 6 H 12 CoN 2 O 8 , monoclinic, P 2 1 / c (no. 14), a = 12.573(5) Å, b = 7.212(3) Å, c = 11.652(5) Å, β = 98.045(6) ° , V = 1046.1(7) Å 3 , Z = 4, R gt ( F ) = 0.0310, wR ref ( F 2 ) = 0.0674, T = 293 K.


Source of material
The structure solution and the refinement were carried out using SHELX program [2,3].All H atoms were located geometrically and refined in calculated positions.Hydrogen atoms from water were located from a difference-Fourier map and their positions were refined with U iso (H) set to 1.5 U eq (O) [4].

Experimental details
All chemical reagents were purchased from commercial sources without further purification.The 1-(carboxymethyl)-1H-pyrazole-3-carboxylic acid was synthesized according to the literature reported by Zhao [5].A mixture of CoCl 2 •6H 2 O (0.0237 g, 0.1 mmol) and 1-(carboxymethyl)-1H-pyrazole-3-carboxylic acid (0.0255 g, 0.15 mmol) were dissolved in 10 mL EtOH/H 2 O (1:1 vol ratio), and the solution was stirred at room temperature for 15 min.The resulting solution was put into a Teflon-lined autoclave (20 mL) for 5 days at 120 °C, then cooled to room temperature slowly, and red block crystals were obtained.

Comment
Pyrazole carboxylic acid is an important pyrazolate compound that combines the characteristics of pyrazole ring and carboxylic acid.Due to its different functional donor atoms N and O, this type of compound has a rich coordination mode and strong coordination ability, making it a good ligand [6].This type of compound also has a certain degree of rigidity and stability in structure, and the coordination plane of the carboxyl group is rotatable and flexible in orientation, Therefore, it can coordinate with metal ions to form complexes with novel structures and diverse functions [7].Moreover, pyrazole-N-donor ligands carrying multicarboxylate groups were easily in facile preparation of mononuclear, dinuclear and polymeric transition metal(II) complexes [8].
The title complex crystallizes in monoclinic system P2 1 /c group, and the asymmetric unit consists of one Co(II) ion, one deprotonated ligand ions and four coordinated water molecules.The central Co(II) ion adopts a distorted octahedral coordination configuration, and is coordinated to four water molecules, one carboxylate oxygen atom and one nitrogen atom of the ligand.In the octahedral, the bond length of Co1-N2 is 2.1365(17) Å, the bond length of Co1-O2 is 2.0705(15) Å, the bond length of Co1-O5 is 2.0925(15) Å, the bond length of Co1-O6 is 2.0896(16) Å, the bond length of Co1-O7 is 2.0350(16) Å, and the bond length of Co1-O8 is 2.1808(15) Å, which is similar to that reported in Co(II) analogue [9,10].The bond angle of O-Co1-N is in the range of 77.69(6)-166.00(6)°, and the O-Co1-O bond angle is in the range of 85.02(6)-176.23(6)°,which are all within the normal range.There also exist four coordinated water molecules in the crystal structure of title complex, which could form abundant hydrogen bonds.A number of O-H⋯O hydrogen bonds in the compound is present, thereby resulting a supramolecular architecture.

Table  :
Fractional atomic coordinates and isotropic or equivalent isotropic displacement parameters (Å  ).