Chiral titanium(IV) and vanadium(V) salen complexes were found to catalyse the synthesis of cyclic carbonates from carbon dioxide and epoxides. Reactions could be conducted at room temperature and 50 bar pressure of carbon dioxide or at 100 °C and atmospheric pressure with catalyst concentrations as low as 0.1 mol% and co-catalyst (tetrabutylammonium bromide) concentrations as low as 0.5 mol%. The cyclic carbonates formed were racemic and a mechanism is proposed which relies on Lewis base catalysis to activate the carbon dioxide rather than Lewis acid catalysed activation of the epoxide as more commonly proposed for catalysis by metal complexes.
Bibliographical noteFunding Information:
This work was supported by the Ministry of Science and Higher Education of the Russian Federation . Quantum chemical calculations were supported by the Russian Science Foundation grant # 17-13-01526 . The authors acknowledge the computational resources provided by the Moscow State University’s Faculty of Computational Mathematics and Cybernetics (IBM Blue Gene/P, Polus). The research was carried out using the equipment of the shared research facilities of HPC computing resources at Lomonosov Moscow State University [ 33 ]. The Siberian Branch of the Russian Academy of Sciences (SB RAS) Siberian Supercomputer Center is gratefully acknowledged for providing supercomputer facilities. This work has been carried out using computing resources of the federal collective usage centre Complex for Simulation and Data Processing for Mega-science Facilities at NRC “Kurchatov Institute”, http://ckp.nrcki.ru/ .
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- Carbon dioxide
- Cyclic carbonate
- Salen ligand