Abstract
A series of new porphyrins with ZnII, CoII, and CuII (1-3) as metal centers are reported. These complexes were evaluated in the CO2 cycloaddition reaction with epoxides under mild conditions (30-80°C and 1 bar of CO2 pressure) and solvent-free conditions; in optimal conditions, they presented high conversions (>99 %) and selectively produced styrene cyclic carbonate. To comprehend the mechanism of the reaction, synchronously, a kinetic approach was carried out using the 1/TBAB system and only TBAB to evaluate the activation energy (Ea) for catalyzed and uncatalyzed reactions. The results support the synergism between the catalyst and the cocatalyst decreasing the Ea in 20.48 kJ mol−1. In addition, the thermodynamics parameters (ΔG‡, ΔH‡, ΔS‡) were also determined using Eyring´s equation. Moreover, a unique example of a dormant species for catalyst 3 bearing two DMAP axially coordinated to CoII was determined by X-ray diffractometry. Theoretical studies also supported the experimental data; the catalytic cycle has been revealed at the molecular level and pointed out the best epoxide activation for the ZnII complex.
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
