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.将2当量的三乙基硅氢（HSiEt3）加入到含1当量三(五氟苯基)硼（B(C6F5)3）的UO₂(Aracnac)₂体系中，其中配体Aracnac为ArNC(Ph)CHC(Ph)O，芳基Ar为3,5-二叔丁基苯基（3,5-tBu₂C₆H₃），反应以80%的产率生成五价铀（U(V)）双(硅氧基)配合物[U(OSiEt₃)₂(Aracnac)₂][HB(C₆F₅)₃]（标记为1）。该反应同时会生成少量副产物U(OSiEt₃)(OB{C₆F₅}₃)(Aracnac)₂（标记为2）。值得注意的是，将配合物1在85℃下热解24小时，同样可得到配合物2，同时伴随生成三乙基硅烷（Et₃SiH）。向配合物1中加入1当量的二茂钴（Cp₂Co），可生成U(OSiEt₃)₂(Aracnac)₂（标记为3）与[Cp₂Co][HB(C₆F₅)₃]（标记为4），二者的分离产率分别为61%和71%。配合物1至3均通过X射线晶体衍射（X-ray crystallography）完成结构表征，而配合物1的溶液相氧化还原性质则通过循环伏安法（cyclic voltammetry）进行了测定。