N-heterocyclic carbene-pyridine ligand coordinated Mo(II) complexes catalyzed synthesis of cyclic carbonates from carbon dioxide and epoxides

Jianwen Li, Sheng Tao, Fei Chen, Min Li*, Ning Liu*. Journal of CO2 Utilization 2023, 69, 102384.

Abstract
A variety of zero-valent molybdenum complexes and divalent molybdenum complexes with N-heterocyclic carbenes (NHC)-pyridine ligands were synthesized, and their catalytic activities and performances in the cycloaddition reaction of epoxides and carbon dioxide (CO₂) were investigated. It was found that the divalent molybdenum complexes show high catalytic activity in the synthesis of cyclic carbonates from epoxide and CO₂ in comparison with zero-valent molybdenum complexes. The divalent molybdenum complexes combined with tetrabutylammonium iodide (TBAI) can effectively transform various terminal epoxides and internal epoxides under 30–80 ℃ and 5–10 bar of CO₂ pressure. The mechanic experiments by FT-IR and HRMS spectrometry reveal the reaction pathway of binary system in combination of divalent molybdenum complexes with TBAI.