Two-Electron Reduction of a U(VI) Complex with Al(C5Me5).

The reduction of U(VI) to U(IV) is rare, especially in one step, and not observed electrochemically as a one-wave, two-electron couple. Here, we demonstrate that reduction of the uranium(VI) bis(imido) complex, (C5Me5)2U[═N(4-OiPrC6H4)]2, is readily accomplished with Al(C5Me5), forming the bridging uranium(IV)/aluminum(III) imido complex (C5Me5)2U[μ2-N(4-OiPrC6H4)]2Al(C5Me5). The structure and bonding of the bridging imido complex is examined with electrochemical measurements in tandem with density functional theory calculations.