A new coordination complex based on 2,2′-dipyridinium ligand as catalyst for the conversion of CO2 to propylene carbonate

Abstract

Based on the ligand 2,2′-dipyridylamine (Hdpa) and di（2-pyrazyl）amine（Hdpza）, neutral molecular complexes [Co(Hdpa)2(NCS)2] (1) and [Co(Hdpza)2(NCS)2] (2) were synthesized. The DFT calculation of complex 1 was carried out to analyze the electron density distribution. Magnetic results indicate that a gradual decrease in χMT over the entire temperature range indicates strong zero-field splitting for the high-spin Co(II) ion in 1. The complex was used for the cycloaddition reaction of CO2 and propylene oxide, and compared with the reported complex 2 [Co(Hdpza)(NCS)2], the catalytic activity was 1 > 2. The Complex 1 exhibited excellent catalytic performance for converting CO2 into cyclic carbonates under mild conditions. For propylene oxide (PO) and CO2 synthesis of propylene carbonate (PC), the catalytic system showed a remarkable TOF as high as 5040 h−1.