In this study, the structurally similar multinuclear cobaloxime complexes based on dioxime ligands were synthesized and characterized as trinuclear complexes with respect to varied axial groups. The multinuclear cobaloxime complexes were characterized by ¹H, ¹³C-NMR, FT-IR, UV-Vis, LC-MS spectra, melting point and magnetic susceptibility measurements. These multinuclear cobaloxime complexes have been successfully applied to the synthesis of cyclic carbonates from CO₂ and epoxides under optimized conditions and with-out using any solvent. All multinuclear cobaloxime complexes obtained by click chemistry are good catalysts for the cycloaddition of CO₂ to different epoxides in the presence of pyridine as a co-catalyst. Additionally, the effects of epoxides, bases, temperature, pressure, and time on the yield of cyclic carbonates were investigated.

Two novel tridentate SNS pincer type ligands, 2,6-bis[[(2^'-methoxyphenyl)thio]methyl]pyridine (L1) and 2,6-bis[[(2^'-chlorophenyl)thio]methyl]pyridine (L2), each possessing two sulfur and one nitrogen donor functionalities (SNS), based on 2,6-bis(thioether)pyridine ligands were prepared and metallised with CuCl₂ · 2H₂O and FeCl₂ · 4H₂O metal salts. Two new unanticipated complexes were obtained from the L,2 ligand, the dimeric bidentate Cu(I) complex [Cu₂(κ²−L2)₂Cl₂] and tridentate Fe(II) complex [Fe(κ³−L2)Cl₂] while two new tridentate pincer-type complexes M(κ³-L1)Cl₂] (M = Cu, Fe) were formed from the L1 ligand It was observed that the structure of this Cu(I) complex has a tetrahedral geometry using single crystal Xray diffraction analysis. In addition, catalytic properties of metal complexes towards the formation of cyclic carbonates from CO2 and epoxides were investigated. The less sterically hindered Fe(II) complex with theL1 ligand [Fe(κ³−L1)Cl₂] (2) showed the best catalytic activity. Several parameters including temperature, time, epoxide identity and CO₂ pressure were investigated to find the optimum catalytic reaction conditions. Moreover, DFT studies of these compounds are presented in the study.