Geçiş metallerinin naftilsalisialdiminlerle kompleks bileşiklerinin sentezi, yapı ve spektral özelliklerinin incelenmesi

Abstract

59 7. SUMMARY A new series of copper(II), nickel(II) and cobalt(II) chelates containing the binucleating tetradentate Schiff base ligands N,N'-bis(salicylidene)-naphthalene-1,5- diamine (LH), N,N'-bis(3-methoxy-salicylidene)-naphthalene-l,5-dianiine (L2H) and N,N'-bis(4-hydroxy-salicylidene)-naphthalene-l,5-diamine (LjH), N,N'-bis(5-brom- salicylidene)-naphthalene-l,5-diamine (L4II), N,N'-bis(3,5-di-brom-salicylidene)- naphthalene-l,5-diamine (L5II) have been synthesized. These compounds have been characterized by elemental analyses, conductivity measurements, magnetic susceptibility, thermoanalyses (TG-DTA), infrared and electronic spectral data. The results suggest that the Schiff bases function as tetradentate ligands coordinating through the ONNO donor system and indicate a binuclear structure for Cu(II) complexes with tetragonal geometry and binuclear structures for Co(II) and Ni(II) complexes with octahedral geometry. The analytical data of the chelates show that the metal to ligand ratio in all the complexes is 2:2. The results indicate that the tetradentate Schiff bases can act as a binucleating ligand and can bind to two metal ion, forming binuclear complexes. The composition of the complexes is [ML]2.nH20 for tetragonal Cu(II) and square-planar Ni(TI) complexes, and [ML(H20)2]2.nH20 for octahedral Ni(ll) and Co(H) complexes. All the complexes are sparingly soluble in DMF and soluble in DMSO but extremely insoluble in most common organic solvents and H20. The poor molar conductivity values of IxlO`3 M solutions of all the complexes in DMSO (3.2-8.5 O`1 cm2mor') indicates that the complexes are non-electrolyte in behaviour. From the infrared and electronic absorption spectral studies of the complexes it is presumed that the Schiff base ligands behave in a dibasic tetradentate manner coordinating through 0:N:N:0 sequence.60 The final products of decomposition of the Schiff base complexes are oxides CuO, NiO and C03O.1 which are formed at 500-750 °C. Comparing the temperatures of oxide formation it is possible to suggest that they change regularly with increasing atomic number (Z) of metal. The results indicate that the thermal decomposition of the Cu(II), Ni(II) and Co(II) complexes can be presented in the following manner : [CuLx]2.H20 - ? lCuL*J2- ? CuLx -* CuO lNiL*(H20)2]2.H20 -* [NiLx(H20)2]2 -» [NiLx]2 - ? NiLx - ? NiO [CoLx(H2O)2]2.0.5H2O - ? [CoLx(H20)2]2 - ? [CoLx]2- ? CoLx - ? Co,04 Single crystals of the compounds could not be isolated from any solvent, thus no definite structures can be described. However, the spectroscopic and magnetic susceptibility data enable us to predict possible structures shown in Picture 1 and 3. Molecular models indicate that there are no severe steric strains in attemts to fit all complexes in a square-planar, tetrahedral and an octahedral configuration.

59 7. SUMMARY A new series of copper(II), nickel(II) and cobalt(II) chelates containing the binucleating tetradentate Schiff base ligands N,N'-bis(salicylidene)-naphthalene-1,5- diamine (LH), N,N'-bis(3-methoxy-salicylidene)-naphthalene-l,5-dianiine (L2H) and N,N'-bis(4-hydroxy-salicylidene)-naphthalene-l,5-diamine (LjH), N,N'-bis(5-brom- salicylidene)-naphthalene-l,5-diamine (L4II), N,N'-bis(3,5-di-brom-salicylidene)- naphthalene-l,5-diamine (L5II) have been synthesized. These compounds have been characterized by elemental analyses, conductivity measurements, magnetic susceptibility, thermoanalyses (TG-DTA), infrared and electronic spectral data. The results suggest that the Schiff bases function as tetradentate ligands coordinating through the ONNO donor system and indicate a binuclear structure for Cu(II) complexes with tetragonal geometry and binuclear structures for Co(II) and Ni(II) complexes with octahedral geometry. The analytical data of the chelates show that the metal to ligand ratio in all the complexes is 2:2. The results indicate that the tetradentate Schiff bases can act as a binucleating ligand and can bind to two metal ion, forming binuclear complexes. The composition of the complexes is [ML]2.nH20 for tetragonal Cu(II) and square-planar Ni(TI) complexes, and [ML(H20)2]2.nH20 for octahedral Ni(ll) and Co(H) complexes. All the complexes are sparingly soluble in DMF and soluble in DMSO but extremely insoluble in most common organic solvents and H20. The poor molar conductivity values of IxlO`3 M solutions of all the complexes in DMSO (3.2-8.5 O`1 cm2mor') indicates that the complexes are non-electrolyte in behaviour. From the infrared and electronic absorption spectral studies of the complexes it is presumed that the Schiff base ligands behave in a dibasic tetradentate manner coordinating through 0:N:N:0 sequence.60 The final products of decomposition of the Schiff base complexes are oxides CuO, NiO and C03O.1 which are formed at 500-750 °C. Comparing the temperatures of oxide formation it is possible to suggest that they change regularly with increasing atomic number (Z) of metal. The results indicate that the thermal decomposition of the Cu(II), Ni(II) and Co(II) complexes can be presented in the following manner : [CuLx]2.H20 - ? lCuL*J2- ? CuLx -* CuO lNiL*(H20)2]2.H20 -* [NiLx(H20)2]2 -» [NiLx]2 - ? NiLx - ? NiO [CoLx(H2O)2]2.0.5H2O - ? [CoLx(H20)2]2 - ? [CoLx]2- ? CoLx - ? Co,04 Single crystals of the compounds could not be isolated from any solvent, thus no definite structures can be described. However, the spectroscopic and magnetic susceptibility data enable us to predict possible structures shown in Picture 1 and 3. Molecular models indicate that there are no severe steric strains in attemts to fit all complexes in a square-planar, tetrahedral and an octahedral configuration.