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Heterobimetallic rare earth metal-zinc catalysts for reactions of epoxides and CO 2 under ambient conditions
Four homodinuclear rare earth metal (RE) complexes 1-4 bearing a multidentate diglycolamine-bridged bis(phenolate) ligand were synthesized. In addition, seven heterobimetallic RE-Zn complexes 5-11 were prepared through a one-pot strategy. In these heterobimetallic complexes, two RE centers are bridg...
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Published in: | Dalton transactions : an international journal of inorganic chemistry 2021-02, Vol.50 (4), p.1453-1464 |
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Main Authors: | , , , , , , , |
Format: | Article |
Language: | English |
Citations: | Items that this one cites Items that cite this one |
Online Access: | Get full text |
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Summary: | Four homodinuclear rare earth metal (RE) complexes 1-4 bearing a multidentate diglycolamine-bridged bis(phenolate) ligand were synthesized. In addition, seven heterobimetallic RE-Zn complexes 5-11 were prepared through a one-pot strategy. In these heterobimetallic complexes, two RE centers are bridged by either Zn(OAc)
or Zn(OBn)
moieties. All complexes were characterized by single crystal X-ray diffraction, elemental analysis, IR spectroscopy, and multinuclear NMR spectroscopy (in the case of diamagnetic complexes 1, 4, 7 and 11). Moreover, the multi-nuclear structures of complexes 4 and 11 in solution were also studied by
H DOSY spectroscopy. These complexes were applied in catalyzing the coupling reaction of carbon dioxide (CO
) with epoxides. Zn(OAc)
- and Zn(OBn)
-bridged heterobimetallic complexes showed comparable catalytic activities under ambient conditions and were more active than monometallic RE complexes. Significant synergistic effect in heterobimetallic complexes is observed. Mono-substituted epoxides were converted into cyclic carbonates under 1 atm CO
at 25 °C in 88-96% yields, whereas di-substituted epoxides reacted under 1 atm CO
at higher temperatures in 40-80% yields. |
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ISSN: | 1477-9226 1477-9234 |
DOI: | 10.1039/D0DT03772A |