Silylation of the Uranyl Ion Using B(C6F5)3-Activated Et3SiH

Addition of 2 equiv of HSiEt3 to UO2(Aracnac)2 (Aracnac = ArNC(Ph)CHC(Ph)O, Ar = 3,5-tBu2C6H3) in the presence of 1 equiv of B(C6F5)3 results in formation of the U(V) bis(silyloxide) complex [U(OSiEt3)2(Aracnac)2][HB(C6F5)3] (1) in 80% yield. Also produced in the reaction, as a minor product, is U(OSiEt3)(OB{C6F5}3)(Aracnac)2 (2). Interestingly, thermolysis of 1 at 85 °C for 24 h also results in formation of 2, concomitant with production of Et3SiH. Addition of 1 equiv of Cp2Co to 1 results in formation of U(OSiEt3)2(Aracnac)2 (3) and [Cp2Co][HB(C6F5)3] (4), which can be isolated in 61% and 71% yields, respectively. Complexes 1–3 have been characterized by X-ray crystallography, while the solution-phase redox properties of 1 have been measured with cyclic voltammetry.