Insights into the structure of triethylammoniumbis(pyridine-2,6-dicarboxylato-iron(III)): Crystallographic and theoretical study

A synthesis of Fe(III) dipicolinate complex leads to a new crystalline structure of triethylammonium bis(pyridine-2,6-dicarboxylato-iron(III)). This latter has been determined by single crystal X-ray diffraction analysis, and FT-IR spectroscopy. The title compound crystallizes in space group P-1 of triclinic system with cell parameters: a = 7.9288(6) Å, b = 10.5262(9) Å, c = 14.2351(12) Å, α = 72.552(3)°, β = 86.769(3)°, γ = 70.266(3)°. The asymmetric unit contains an [Fe(pydc)2] (pydc = pyridine-2,6-dicarboxylate) anion and a protonated triethylamine as a conter-ion. Fe ion is coordinated to two perpendicular tridentate ligands in their dianionic form (pydc2−). In addition, the cation and the anion are involved in an extensive three-dimensional hydrogen-bond network which collaborates to the stabilization of the 3D supramolecular structure. The molecular structure was calculated using DFT/B3LYP method at 6–31G(d,p) basis set. The calculated results show that the optimized geometry reproduces well the crystal structure. Electronic chemical potential (µ), chemical hardness (η), electrophilic (ω) and nucleophilic (Nu) descriptors of the title molecule have also been determined. Finally, Fukui functions (fk+ and fk−) and local nucleophilicity (Nuk) indexes were calculated and have been then evaluated.