Struktura, priroda veze i magnetne osobine binuklearnih kompleksa Cu(II) i Ni(II) sa hidrazonskim ligandima / Structure, nature of bond and magnetic properties of binuclear complexes Cu(II) and Ni(II) with hydrazone ligands

Abstract

This dissertation describes the synthesis, characterization and crystal structure of the complexes [CuL1Cl]BF4 (1), [CuL1Cl]NO3 (2), [Cu2L12Cl2](BF4)2 (3) and [Ni2L12(μ-1,1-N3)2(N3)2]6H2O (4), obtained in the reaction of the corresponding Cu(II) and Ni(II) ions and the ligand (E)-N,N,N-trimethyl-2-oxo-2-(2-(1-(pyridin-2-yl)ethylidene)hydrazinyl)ethan-1-aminium chloride (HL1Cl) and complexes [Ni2L22(µ-1,1-N3)2(N3)2]∙2H2O (5a) and [Ni2L22(µ-1,1-N3)2(N3)2]∙4H2O (5b) obtained in the synthesis of Ni(II) ions and the ligand (E)-N,N,N-2-oxo-2-(2-(1-(thiazol-2- -yl)ethylidene)hydrazinyl)ethan-1-aminium chloride, (HL2Cl). All mentioned complexes were characterized in detail in the solid state by X-ray structural analysis, elemental analysis and IR spectroscopy, while for complexes 5a and 5b magnetic susceptibility was also measured. In all complexes 1–5, ligands HL1Cl and HL2Cl are tridentately coordinated via NNO donor set of atoms in a deprotonated, formally neutral, zwitterionic form. In the case of complexes 1 and 2, metal ions with the HL1Cl ligand form mononuclear complex, while in the case of complexes 3 and 4 with the same ligand, binuclear complex is formed. Ligand HL2Cl with Ni(II) ions builds binuclear complexes 5a and 5b. Complexes 5a and 5b were obtained from the same solution, with complex 5a found only in trace amounts. DFT calculations were performed for all complexes, the results of which were in accordance with the experimental data. DFT calculations showed that in the case of mononuclear complexes 1 and 2, there is a weak coordination bond between the central metal ion Cu(II) and the anions BF4– i NO3–, which is of a typical ionic type. For complex 3, DFT calculations showed that the complex exists as a binuclear species, in which two Cu(II) ions are connected to each other by bridging Cl– ligands and that the BF4– anion is not involved in coordination with Cu(II). In the case of complex 4, DFT calculations showed that independently of the applied functionals, ferromagnetic coupling exists between the metal centers. In complexes 5a and 5b, the calculated magnetic interaction according to the DFT approach with meta-hybrid M06-2X and doubly hybrid B2PLYP and PWPB95 functionals shows that in all cases, the model systems based on 5b have lower energy level than those based on 5a. Also, in the case of the optimized structures 5a* and 5b* (at the BP86-D4/TZP level of theory), the optimized structure 5b* has a lower energy state. For complexes 5a and 5b, a temperature-dependent magnetic susceptibility was also measured, which showed that intramolecular interactions between Ni(II) centers are ferromagnetic in nature.