Crystal structure of bis[(triaqua-4-iodopyridine-2,6-dicarboxylato-κ 3 N , O , O ″ )cobalt(II)] trihydrate, C 14 H 22 N 2 O 17 I 2 Co 2

C 14 H 22 N 2 O 17 I 2 Co 2 , monoclinic, P 2 1 / c (no. 14), a = 7.13476(14) Å, b = 11.1853(2) Å, c = 32.5727(5) Å, β = 93.5815(16) ° , Z = 4, V = 2594.38(8) Å 3 , R gt ( F ) = 0.0447, wR ref ( F 2 ) = 0.0865, T = 293.0 K.


Source of material
The reagents were purchased from commercial sources and used without further purification.The title compound was prepared under the hydrothermal conditions.A mixture of Co(NO 3 ) 2 •6H 2 O (29.1 mg, 0.1 mmol), 4-iodopyridine-2,6-dicar boxylic acid (29.2 mg, 0.1 mmol) and 6 mL distilled water was sealed in a 23 mL teflon-lined autoclave, which was kept under autogenous pressure at 353 K for 72 h.After slowly cooling to room temperature at a rate of 5 K h −1 , pale yellow block crystals suitable for X-ray diffraction were collected by filtration and washed with ethanol.

Experimental details
Hydrogen atoms were placed in their geometrically idealized positions and constrained to ride on their parent atoms.

Comment
6][7] Up to now, it is still a long term challenge to prepare such compounds.Noted, rational design of suitable organic ligands and proper choice of metal centers are the main keys to construct and tune of the CrysAlis PRO ,  SHELX, , Olex  resulting compounds. 8,9Furthermore, other non-covalent interactions such as hydrogen-bonding and π-π stacking often affect the final results.Recent plentiful research has been focused on using bridging pyridine carboxylic acid and their derivatives to construct metal compounds.These ligands containing carboxylate oxygen and pyridyl nitrogen atoms can form interesting network structures. 10,11In this work, we report a compound based on 4-iodopyridine-2,6-dicarboxylic acid ligand and central Co(II) centers.From the point of view of structural chemistry, the ligand containing a number of N and O coordination sites is effective for construction of metal compounds.][14] X-ray diffraction analysis has revealed that the compound crystallizes in the monoclinic system with a space group of P2 1 /c.The asymmetric unit consists two Co(II) cations, two deprotonated 4-iodopyridine-2,6-dicarboxylate ligands, six coordinating water molecules and three isolated water molecules.The central Co(1) and Co(2) atoms are both six-coordinated in octahedral geometries generated from two carboxylate oxygen atoms, one pyridine atom and three oxygen atoms from coordinating water molecule.The Co-O bond lengths vary from 1.992(3) to 2.188(3) Å.The bond angles about the Co(II) centers range from 54.85(13)°to 160.41 (14)°.These values are matched with the previously reported other Co(II) compounds. 15n the discrete structure, each 4-iodopyridine-2,6-dicarboxylate ligand coordinates one Co(II) center with a tridentate coordination mode.The vacant positions of Co(II) center are occupied by coordinating water molecules.In addition, there are obviously O-H⋯O hydrogen bonds interactions involving coordinated/isolated water molecules and the carboxylate oxygen atoms.Moreover, there is iodine-based halogen bonds between iodine atoms and the carboxylate oxygen atoms with the distances of 3.169 and 3.295 Å.
Author contribution: All the authors have accepted responsibility for the entire content of this submitted manuscript and approved submission.
Research funding: This work was supported by the Key Scientific and Technological Project of Henan Province Department of China (no.232102321121).

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