Bimetallic, Silylene‐Mediated Multielectron Reductions of Carbon Dioxide and Ethylene

A metal/ligand cooperative approach to the reduction of small molecules by metal silylene complexes (R2Si=M) is demonstrated, whereby silicon activates the incoming substrate and mediates net two‐electron transformations by one‐electron redox processes at two metal centers. An appropriately tuned ca...

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Bibliographic Details
Published in:Angewandte Chemie International Edition 2021-01, Vol.60 (3), p.1615-1619
Main Authors: Whited, Matthew T., Zhang, Jia, Conley, Anna M., Ma, Senjie, Janzen, Daron E., Kohen, Daniela
Format: Article
Language:English
Subjects:
Bimetals
Carbon dioxide
carbon dioxide fixation
Cobalt
Computer applications
Coordination compounds
Cycloaddition
density-functional calculations
Ethylene
Heavy metals
Ligands
Metals
Oxidation
redox chemistry
reduction
Silicon substrates
Siloxanes
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Summary:A metal/ligand cooperative approach to the reduction of small molecules by metal silylene complexes (R2Si=M) is demonstrated, whereby silicon activates the incoming substrate and mediates net two‐electron transformations by one‐electron redox processes at two metal centers. An appropriately tuned cationic pincer cobalt(I) complex, featuring a central silylene donor, reacts with CO2 to afford a bimetallic siloxane, featuring two CoII centers, with liberation of CO; reaction of the silylene complex with ethylene yields a similar bimetallic product with an ethylene bridge. Experimental and computational studies suggest a plausible mechanism proceeding by [2+2] cycloaddition to the silylene complex, which is quite sensitive to the steric environment. The CoII/CoII products are reactive to oxidation and reduction. Taken together, these findings demonstrate a strategy for metal/ligand cooperative small‐molecule activation that is well‐suited to 3d metals. Cobalt silylene complexes perform remarkable reductions of carbon dioxide and ethylene in a cooperative bimetallic process, where the silylene ligands mediate electron transfer from multiple cobalt centers and template the reaction to form either a siloxane or disilylethyl bridge.
ISSN:1433-7851
1521-3773
DOI:10.1002/anie.202011489