Novel Products of Nitrosation of a Series of Trihydroxybenzene Derivatives and Their Complexation with Cu(II), Cd(II) and Fe(III): Synthesis, Characterization, and Theoretical Modeling

Three novel bis- and trinitroso compounds derived from 1,3,5-trihydrohybenzene (phloroglucinol), 2,4,6–trihydroxy benzoic acid, and 2,4,6-trihydroxyacetophenone were isolated, their spectral characteristics, ionization constants and thermodynamic parameters of dissociation process were calculated. The comparison of the stability of nitroso and hydroxylimino tautomeric forms was performed by DFT calculations. Nine complexes of the ligands with Cu(II), Cd(II), and Fe(III), were isolated and studied by elemental analyses, X Ray analysis and spectroscopic methods. According to the crystal structure determination, the Cd complex with the phloroglucinol based ligand exists in the form of a binuclear compound. The QTAIM Bader topological analysis indicated that the binuclearity of the Cd complex is due to strong interatomic interactions between Cd atoms with bifurcate carbonyl groups of the ligands and strong H-interactions involving coordinated and lattice water molecules. The equilibria of reactions of complex formation of the organic species with Cu2+, Cd2+, and Fe3+ was studied by spectrophotometric titration, and the composition of the complexes in solutions and their stability constants were calculated. The ability of the isolated organics to remove metal cations from the aqueous solutions was studied in the pH interval 3–6 and the rate of Cu2+ removal from aqueous solutions was found close to 100 %. © 2021 Wiley-VCH Gmb