Experimental (X-ray, TGA) and computation (NBO, AIM) studies of Iron(II) complex with thiabendazole and 5-aminoisophthalate

In this article, we synthesized the coordination complex: thiabendazole (TBZH) iron 5-aminoisophthalate (AIP), ([(Fe(TBZH)(AIP)(3H(2)O)]center dot 2.5 H2O), and characterized by the X-ray single crystal diffraction analysis, the result reveals the iron center is six coordinated and formed a slightly distorted octahedron coordinated geometry. In the structure, the Nitrogen of AIP adopts kappa N coordination mode connecting the metal center and the two carboxylate groups are deprotonized. The TGA manifests there are three weight loss steps and the residue suggest it to be the ferroferric oxide. The Hirshfeld analysis reveals in d(norm)-surfac, the O(N)-H center dot center dot center dot O hydrogen-bonds corresponds to the dark red spots near the hydrogen-bonds acceptor and donor atoms. The presence of patterns of red-and blue triangles on the same region of the shape-index surfaces is a characteristic of pi center dot center dot center dot pi stacking. The theoretical calculated the molecular orbitals, it shows that the LUMO orbital, the electron cloud is located at coordinated water molecules (O1, O3) and the free water (O1w). The electron cloud of the HOMO orbitals is mainly sited at the carboxylate groups and the benzene rings of AIP. The bond orders reveal the value of Fe-N1 and Fe-N2 are larger than that of the Fe-N4, Fe-O3, Fe-O2 and Fe-O1. The second-order perturbation energy analysis shown the most of the E(2) stabilization energies of LP(N) -> LP *(Fe) is larger than those of the LP(O) -> LP *(Fe), indicating the N atom in complex is the main contributor to the coordination. The AIM analysis found the bond critical point (BCP) of the complex, the electron density value rho(BCP) (from 0.007 to 0.034 a.u.) for the O(C)-H center dot center dot center dot O hydrogen bonds are all in the suggested interval of 0.002-0.035 a.u. the rho(BCP) order of Fe-N and Fe-O sequences are rho(BCP(Fe-N1)) > rho(BCP(Fe-N2)) > rho(BCP(Fe-N4)) and rho(BCP(Fe-O1)) > rho(BCP(Fe-O3)) > rho(BCP(Fe-O2)) shown the firm degree of the bond, these are consistent with the bond order. The Laplacian of electron density (backward difference 2 rho BCP) are positive and the vertical bar v(r)vertical bar/g(r) < 1 indicated the O(C)-H center dot center dot center dot O are mainly closed shell and Fe-O(N) interactions are the intermediate character between the closed shell and the typically covalent interaction. (C) 2021 Elsevier B.V. All rights reserved.

Automated summary

In this study, a coordination complex was synthesized and characterized, revealing a six-coordinated iron center with a slightly distorted octahedral coordination geometry. Thermal analysis showed three weight loss steps and identified the residue as ferroferric oxide. Hirshfeld analysis and theoretical calculations provided insights into the molecular structure and electron cloud distribution.