Extraction-spectrophotometric and theoretical (Hartree-Fock) investigations of a ternary complex of iron(II) with 4-nitrocatechol and 2,3,5-triphenyl-2H-tetrazolium

Abstract

The complex formation and solvent extraction were studied in a system containing iron(II), 4nitrocatechol (4NC), 2,3,5-triphenyl-2H-tetrazolium chloride (TTC), water, and chloroform. Under the optimum conditions, the extracted complex has a composition of 1 : 1 : 2 (Fe-4NC-TTC) and could be represented with the formula (TT + ) 2 [Fe II (4NC 2-)(OH) 2 ]. Theoretical calculations were performed at the HF/3-21G* level in order to elucidate the geometric structure of the complex and electron distribution according to the crystal field theory. The results showed that the most stable configuration is tetrahedral low-spin structure. Some equilibrium constants (association, distribution, and extraction) and characteristics (absorption maximum, molar absorption coefficient, recovery factor, Beer's law limits, etc.) concerning the application potential of the studied extraction-chromogenic system were determined.

Complex formation in a liquid-liquid extraction-chromogenic system for vanadium(IV)

“…The results obtained allowed the modelling of the structure of the entire ion-association complex. For this purpose, we combined structure III with the pre-optimized structure of the tetrazolium cation [16,53]. In addition to the HF calculations, we carried out calculations based on DFT.…”