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Controlling selectivity in the reductive activation of CO2 by mixed sandwich uranium(III) complexes

journal contribution
posted on 2023-06-08, 20:15 authored by Nikolaos Tsoureas, Ludovic Castro, Alexander F R Kilpatrick, Geoff Cloke, Laurent Maron
The synthesis and molecular structures of a range of uranium(III) mixed sandwich complexes of the type [U(?8-C8H6(1,4-SiMe3)2)(?5-CpMe4R)] (R = Me, Et, iPr, tBu) and their reactivity towards CO2 are reported. The nature of the R group on the cyclopentadienyl ring in the former has a significant effect on the outcome of CO2 activation: when R = Me, the products are the bridging oxo complex {U[?8-C8H6(1,4-SiMe3)2](?5-CpMe5)}2(µ-O) and the bridging oxalate complex {U[?8-C8H6(1,4-SiMe3)2](?5-CpMe5)}2(µ-?2:?2-C2O4); for R = Et or iPr, bridging carbonate {U[?8-C8H6(1,4-SiMe3)2](?5-CpMe4R)}2(µ-?1:?2-CO3) and bridging oxalate complexes {U[?8-C8H6(1,4-SiMe3)2](?5-CpMe4R)}2(µ-?2:?2-C2O4) are formed in both cases; and when R = tBu the sole product is the bridging carbonate complex {U[?8-C8H6(1,4-SiMe3)2](?5-CpMe4tBu)}2(µ-?1:?2-CO3). Electrochemical studies on both the uranium(III) complexes and the dimeric uranium(IV) CO2 reduction products have been carried out and all exhibit quasi reversible redox processes; in particular, the similarities in the U(III)/U(IV) redox couples suggest that the selectivity in the outcome of CO2 reductive activation by these complexes is steric in origin rather than electronic. The latter conclusion is supported by a detailed computational DFT study on the potential mechanistic pathways for reduction of CO2 by this system.

History

Publication status

  • Published

File Version

  • Published version

Journal

Chemical Science

ISSN

2041-6520

Publisher

Royal Society of Chemistry

Issue

10

Volume

5

Page range

3777-3788

Department affiliated with

  • Chemistry Publications

Full text available

  • No

Peer reviewed?

  • Yes

Legacy Posted Date

2015-03-09

First Compliant Deposit (FCD) Date

2021-03-09

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