CO2 Activation with Formation of Uranium Carbonate Complexes in a Closed Synthetic Cycle

Waldschmidt P, Hörger C, Riedhammer J, Heinemann FW, Hauser C, Meyer K (2020)

Publication Type: Journal article

Publication year: 2020

Journal

DOI: 10.1021/acs.organomet.9b00786

Abstract

A closed synthetic cycle for the transformation of carbon dioxide to carbonate with a mid-valent tris(aryloxide)-ligated uranium(IV) terminal oxo complex is presented herein. Starting from the previously reported uranium(III) complex, [U^III(OAr^Ad,Ad,Me)3], the uranium(V) terminal oxo complex, obtained by oxidation with N2O or NO, can be reduced with KC8 to yield CO2 activating anionic uranium(IV) oxo complexes [(^Ad,Ad,MeArO)3U^IV(O)]^-. The cycle proceeds with the formation of [(^Ad,Ad,MeArO)2(κ²-^Ad,Ad,MeArOCO2)U^IV(μ-κ¹:κ²-CO3)]^- upon reaction of the oxo anion with excess CO2 that adds to the terminal oxido ligand and inserts into the uranium-aryloxide bond. Treating this complex with trimethylsilyl halide eliminates both carbonates and generates, for instance, [K(2.2.2-crypt)][(^Ad,Ad,MeArO)3U^IV(I)2], which can ultimately be reduced with KC8 to recover the trivalent starting material, thus closing the cycle. In contrast, reaction of the 18-crown-6 stabilized U(IV) oxo analogue with CO2 yields a rare and isolable example of a uranium complex with a μ-κ¹:κ²-CO3-bound carbonate weakly interacting with the [K(18-crown-6)(THF)]⁺ moiety; here, CO2 insertion and formation of an aryl carbonate ligand are not observed.

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How to cite

APA:

Waldschmidt, P., Hörger, C., Riedhammer, J., Heinemann, F.W., Hauser, C., & Meyer, K. (2020). CO2 Activation with Formation of Uranium Carbonate Complexes in a Closed Synthetic Cycle. Organometallics. https://doi.org/10.1021/acs.organomet.9b00786

MLA:

Waldschmidt, Pablo, et al. "CO2 Activation with Formation of Uranium Carbonate Complexes in a Closed Synthetic Cycle." Organometallics (2020).

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