Institute of Inorganic Chemistry, University of Regensburg, 93040, Regensburg, Germany.
Institute of Biophysics and Physical Biochemistry, University of Regensburg, Germany.
Angew Chem Int Ed Engl. 2018 Mar 12;57(12):3256-3261. doi: 10.1002/anie.201712884. Epub 2018 Feb 21.
The oxidation chemistry of the complexes [{CpMo(CO) } (μ,η :η -E )] (E=P (A), As (B), Sb (C), Bi (D)) is compared. The oxidation of A-D with [Thia] (=[C H S ] ) results in the selective formation of the dicationic E complexes [{CpMo(CO) } (μ ,η :η :η :η -E )] (E=P (1), As (2), Sb (3), Bi (4)), stabilized by four [CpMo(CO) ] fragments. The formation of the corresponding monocations [A] , [C] , and [D] could not be detected by cyclic voltammetry, EPR, or NMR spectroscopy. This finding suggests that dimerization is fast and that there is no dissociation in solution, which was also predicted by DFT calculations. However, EPR measurements of 2 confirmed the presence of small amounts of the radical cation [B] in solution. Single-crystal X-ray diffraction revealed that the products 1 and 2 feature a zigzag E chain in the solid state while 3 and 4 bear a central E cage with a distorted "butterfly-like" geometry. Additionally, 1 can be easily and reversibly converted into a symmetric and an unsymmetric form.
[{CpMo(CO)}_2(μ,η :η -E )]（E=P（A）、As（B）、Sb（C）、Bi（D））配合物的氧化化学性质进行了比较。用[Thia]（=[CHS]）氧化 A-D 可选择性地生成二阳离子 E 配合物[{CpMo(CO)}_2(μ,η :η :η :η -E )]（E=P（1）、As（2）、Sb（3）、Bi（4）），由四个[CpMo(CO)]片段稳定。通过循环伏安法、EPR 或 NMR 光谱无法检测到相应的单阳离子[A]、[C]和[D]的形成。这一发现表明，二聚化速度很快，在溶液中没有解离，这也被 DFT 计算所预测。然而，对 2 的 EPR 测量证实了溶液中存在少量的自由基阳离子[B]。单晶 X 射线衍射表明，产物 1 和 2 在固态中具有锯齿形 E 链，而 3 和 4 具有中心 E 笼，呈扭曲的“蝴蝶状”几何形状。此外，1 可以很容易地和可逆地转化为对称和不对称形式。
