Concomitant Carboxylate and Oxalate Formation From the Activation of CO(2) by a Thorium(III) Complex

Improving our comprehension of diverse CO(2) activation pathways is of vital importance for the widespread future utilization of this abundant greenhouse gas. CO(2) activation by uranium(III) complexes is now relatively well understood, with oxo/carbonate formation predominating as CO(2) is readily reduced to CO, but isolated thorium(III) CO(2) activation is unprecedented. We show that the thorium(III) complex, [Th(Cp′′)(3)] (1, Cp′′={C(5)H(3)(SiMe(3))(2)‐1,3}), reacts with CO(2) to give the mixed oxalate‐carboxylate thorium(IV) complex [{Th(Cp′′)(2)[κ(2)‐O(2)C{C(5)H(3)‐3,3′‐(SiMe(3))(2)}]}(2)(μ‐κ(2):κ(2)‐C(2)O(4))] (3). The concomitant formation of oxalate and carboxylate is unique for CO(2) activation, as in previous examples either reduction or insertion is favored to yield a single product. Therefore, thorium(III) CO(2) activation can differ from better understood uranium(III) chemistry.