Synthesis and characterization of ionic functionalized cobalt and chromium complexes derived from salicylaldimine ligands: Application as catalysts in the coupling of carbon dioxide with propylene oxide

Abstract

Abstract A series of new ionic functionalized chromium and cobalt complexes, 1 – 6, derived from salicylaldimine ligands is reported. Chromium complexes (1 – 4) were obtained by reacting CrCl2 and CrCl3·(THF)3 with the sodium salts of ligands HL2 and HL3 to produce the Cr(II) and Cr(III) analogues respectively. Tetracoordinate Co(II) complexes (5 and 6) were obtained by reacting HL2 and HL3 with Co(OAc)2·4H2O in the presence of sodium hydroxide. The analysis of the complexes with several analytical techniques confirmed the structure and composition of the complexes. All six complexes were evaluated as catalyst for the coupling of CO2 and propylene oxide with all the complexes exhibiting activity for the coupling reaction at 80\xa0°C without the use of a co-catalyst producing propylene carbonate (PC) as coupling product.