Salalen vs. thiolen: in the ring(-opening of epoxide and cyclic carbonate formation)

Abstract

A range of Fe(iii)-salalen and -thiolen–chloride complexes have been prepared and are shown to be active catalysts for the selective coupling of CO2 and cyclohexene oxide (CHO).

Metal Complexes Bearing Sulfur-Containing Ligands as Catalysts in the Reaction of CO2 with Epoxides

“…More recently, Jones and coworkers reported on the synthesis of a wide family of iminethioether-bridged bis(phenolate) ([ONSO]-type) Fe(III) complexes 29-34 ( Figure 19) [72]. The cycloaddition reaction of CO 2 to HO was used as the benchmark reaction to test the catalytic activity of these complexes: on one hand, for the Fe(II) complexes the activity depended on the complex structure, with 26 being the most active (TOF = 36 h −1 ), on the other hand all the Fe(III) species showed comparable activities (TOF = 32 h −1 ).…”

“…More recently, Jones and coworkers reported on the synthesis of a wide family of imine-thioether-bridged bis(phenolate) ([ONSO]-type) Fe(III) complexes 29-34 ( Figure 19) [72].…”

“…More recently, Jones and coworkers reported on the synthesis of a wide family of iminethioether-bridged bis(phenolate) ([ONSO]-type) Fe(III) complexes 29-34 ( Figure 19) [72]. The most active catalytic system, complex 33, could reach a TOF of 156 h −1 by increasing the temperature to 120 • C. However, under this condition, a lower selectivity was detected, because of the simultaneous production of the polyether product.…”

Integration of polypyridyl-based ionic liquids into MIL-101 for promoting CO2 conversion into cyclic carbonates under cocatalyst-free and solventless conditions

“…4 It is still a tremendous challenge to develop an efficient catalytic system for the preparation of cyclic carbonates under cocatalyst-free and solventless conditions. To date, a variety of homogeneous and heterogeneous catalysts have been employed in the CO 2 -cycloaddition reaction, including metal-salen complexes, 5 organic compounds, 6 metal oxides, 7 molecular sieves, 8 and covalent polymers. 9 It is well-known that homogeneous catalysts usually promote the conversion of epoxides through site-specific functional groups.…”

Ring-Opening Copolymerization Using Simple Fe(III) Complexes and Metal- and Halide-Free Organic Catalysts

“…Recently, we reported the simple synthesis and application of a large range of air-stable, Fe­(III)–acetate complexes, consisting of varying salalen, salan, and salen ligand frameworks, for selective coupling of CO 2 with multiple epoxides, predominately CHO, to exclusively form the cis -cyclohexene carbonate product ( cis -CHC) . We have also reported the synthesis and application of Fe­(III)–salalen {ONNO} and −thiolen–chloride {ONSO} complexes to both the isoselective ROP of rac -lactide ( rac -LA) and CO 2 /epoxide coupling to again form cyclic organic carbonate products. − Due to the success we have found in these reactions, the limited examples of Fe-mediated ROCOP, and the growing importance of this area coupled with the benefits Fe holds, we decided to explore the coupling of PA and CHO herein. Additionally, with the large range of Fe­(III) catalysts at our disposal, we wanted to partake in a comprehensive study using 14 different structural frameworks to determine structure–activity relationships; similar to that recently achieved by Kerton and co-workers in CO 2 /epoxide ROCOP to form polycarbonates, and as far as we know, this has not been attempted to such scale before in this area .…”