Synthesis, spectroscopic, thermic and structural properties research of pyridine-2,3-dicarboxylate complexes with cobalt(II), zinc(II), silver(I) and cadmium(II)

In this study, four complexes of Co(II), Ag(I), Zn(II) and Cd(II) transition metal ions with pyridine-2,3-dicarboxylate (pydk) were synthesized. As a secondary ligand, ethylenedi- amine (en) ve 1,3-diaminopropane (dap) has been used in the syntheses of Co(II) and Ag(I)-pyridine-2,3-dicarboxylate complexes, relatively. The structural complexes were characterized by using elemental analyses, magnetic susceptibilities, FT-IR, UV-vis., single crystal X-ray diffraction and thermal analysis techniques (TG-DTA-DTG). According to analysis results, empricial formula of the complexes are [Co(H2O)6][Co(pydk)2(en)]2?14H2O (1), {(NH4)2[Zn( ? -pydk)2]?2H2O}n (2), [Ag2(?-pydk)2(Hdap)2] ? 2H2O (3) and {(NH4)2[Cd( ? -pydk)2]?2H2O}n (4). In these complexes, dianionic pyridine-2,3-dicarboxylate is coordinated to metal ions as bidentate in 1 complex, tridentate in 2, 3 and 4 complexes. Co(II) complex was paramagnetic, Zn(II), Ag(I) and Cd(II) complexes were diamagnetic have been determined with magnetic succeptibility studies 1, 2, and 4 complexes have distorted octahedral geometry and complex 3 also have trigonal pyramidal geometry. The complex 1 is trinuclear, 2 and 4 are polynuclear and 3 isdinuclear structure. When UV-vis. spctrum of Co(II) was investigated in 460 nm abroad band observed corresponding to 4A2g?4T1g transition. The first endothermic stage corresponds to the loss of the water and/or NH3 molecules by thermal analysis studies. The following stages are related to the partly or completely release of ligands. In the exothermic last stages, remaining organic part was abruptly burnt. The final decomposition products are corresponding metal or metal oxides. According to single crystal X-ray diffraction analysis results; complex 1 that includes Co(II) and Co(III) ions with mixed valance is ionic, also it contains trimer water cluster. 2 and 4 complexes are coordination polymer two dimensional. In 3 compound, there are intramolecular anagostic and inter-molecular C-H???Ag interactions.