Silylation of the uranyl ion using B(C6F5)3-activated Et3SiH.

Addition of 2 equiv of HSiEt(3) to UO(2)((Ar)acnac)(2) ((Ar)acnac = ArNC(Ph)CHC(Ph)O, Ar = 3,5-(t)Bu(2)C(6)H(3)) in the presence of 1 equiv of B(C(6)F(5))(3) results in formation of the U(V) bis(silyloxide) complex [U(OSiEt(3))(2)((Ar)acnac)(2)][HB(C(6)F(5))(3)] (1) in 80% yield. Also produced in the reaction, as a minor product, is U(OSiEt(3))(OB{C(6)F(5)}(3))((Ar)acnac)(2) (2). Interestingly, thermolysis of 1 at 85 °C for 24 h also results in formation of 2, concomitant with production of Et(3)SiH. Addition of 1 equiv of Cp(2)Co to 1 results in formation of U(OSiEt(3))(2)((Ar)acnac)(2) (3) and [Cp(2)Co][HB(C(6)F(5))(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.