Title : Synthesis and study of [Co(C₆H₄(NH₂)₂SO₄]ₙ polymer complex obtained on the basis of 1,2-diaminobenzene
Abstract:
This study reports the synthesis and crystal structure analysis of a new polymer complex, $[Co(C_6H_4(NH_2)_2SO_4]_n$, derived from 1,2-diaminobenzene (ortho-phenylenediamine, OPD) and cobalt(II) sulfate. The complex was synthesized via a controlled reaction between an aqueous solution of $CoSO_4 \cdot 6H_2O$ and an alcoholic solution of OPD at 60°C. Single crystals suitable for X-ray diffraction were obtained through slow evaporation in penicillin vials over a ten-day period.
X-ray crystallographic analysis reveals that the complex crystallizes in the orthorhombic syngony with the $Pbcn$ space group. The unit cell parameters are $a = 23.3904 \text{ Å}$, $b = 9.4686(5) \text{ Å}$, and $c = 6.8462(3) \text{ Å}$. The $Co(II)$ center exhibits a tetrahedral coordination geometry with a coordination number of 4. The metal atom occupies a center of symmetry, where two OPD ligands coordinate through donor-acceptor bonds, while the oxygen atoms of the sulfate anions form covalent bonds with a length of $2.34 \text{ Å}$.
The crystal lattice is stabilized by a network of intramolecular and intermolecular hydrogen bonds. Specifically, $N-H \dots O$ type interactions (e.g., $N1-H1 \dots O2$ with a distance of $2.851(3) \text{ Å}$) play a crucial role in forming the polymeric framework. This research provides significant insights into the coordination behavior of OPD with d-metals and the formation of stable metal-organic polymers.
