Synthesis and catalytic application to form cyclic carbonates of novel Pd(II) Cu(II), and Fe(II) benzoate-based Schiff base metal complexes

Abstract

This work describes the synthesis and characterisation of six novel Schiff base complexes, Cu(II), Pd(II), and Fe(II), which, under the right circumstances, function as very efficient catalysts for the production of cyclic carbonates from CO₂ and epoxides. FT-IR spectroscopy, elemental analysis, UV–Vis spectroscopy, molar conductivity, melting point, and magnetic susceptibility measurements are among the spectroscopic methods used to characterize newly synthesized complexes. The molar conductivity values, ranging from 2.58 to 4.03 µS/cm, suggest that the complexes exhibit no molar conductivity. Co-catalysts, such as 4-(dimethylamino)pyridine, pyridine, triethylamine, and triphenyl phosphine, were used in these processes, both with and without one. 4-(Dimethylamino)pyridine was used as the co-catalyst in the catalytic studies. Additionally, a number of variables that affect the cycloaddition process were examined, including the temperature, CO₂ pressure, reaction time, and co-catalyst. All novel catalysts exhibited exceptional catalytic activity and selectivity in the catalytic assays. Regarding the coupling of CO₂ and epichlorohydrin as epoxides, the L2-Cu catalyst outperformed other catalysts in terms of catalytic activity (90.7%) and selectivity (98.9%).