Activation of carbon suboxide (C3O2) by U(III) to form a cyclobutane-1,3-dione Ring.

The activation of C3O2 by the U(III) complex [U(?5-Cp’)3] (Cp’ = C5H4SiMe3) is described. The reaction results in the reductive coupling of three C3O2 units to form a tetranuclear complex with a central cyclobutane-1,3-dione ring, with concomitant loss of CO. Careful control of reaction conditions has allowed the trapping of an intermediate, dimeric bridging ketene complex, which undergoes insertion of C3O2 to form the final product.