Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom
Acyclic Germylones: Congeners of Allenes with a Central Germanium Atom
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DOI：
10.1021/ja406112u
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发表时间：
2013-08-21
影响因子：
15
通讯作者：
Andrada, Diego M.
中科院分区：
文献类型：
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作者：
Li, Yan;Mondal, Kartik Chandra;Andrada, Diego M.
以GeCl2(二氧六环)、CaAc：和KC8为原料，以1：2：2.1的摩尔比一锅法合成了环烷(氨基)卡宾(CAAc：)稳定的开环生殖酮(Me-2-CAAc：)(2)Ge(1)和(Cy-2-CAAc：)(2)Ge(2)。化合物1和2的深绿色晶体的产率分别为75%和70%。已报道的制备相应硅化合物的方法被证明不适用于锗。1和2的单晶X射线结构以C-Ge-C弯曲主干为特征，具有三中心两电子pi-键体系。化合物1和2是第一个含有一个Ge原子和两个CAAc：分子的开环化合物。化合物1和2的EPR测量证实了其为单重态自旋基态。1/2的密度泛函理论计算表明，单重态的稳定性比三重态的稳定程度高16~18kcal(-1)。理论计算的第一和第二质子亲和力分别为265.8(1)/267.1(2)和180.4(1)/183.8(2)千卡摩尔(-1)。在不同水平上进行的进一步计算表明，1和2是单重态双自由基特征。TD-DFT计算表明，在正己烷溶液中有一个类似于655 nm的吸收带，该吸收带源于Germylone 1和2的双自由基特征。
The cyclic alkyl(amino) carbene (cAAC:)-stabilized acyclic germylones (Me-2-cAAC:)(2)Ge (1) and (Cy-2-cAAC:)(2)Ge (2) were prepared utilizing a one-pot synthesis of GeCl2(dioxane), cAAC:, and KC8 in a 1:2:2.1 molar ratio. Dark green crystals of compounds 1 and 2 were produced in 75 and 70% yields, respectively. The reported methods for the preparation of the corresponding silicon compounds turned out to be not applicable in the case of germanium. The single-crystal X-ray structures of 1 and 2 feature the C-Ge-C bent backbone, which possesses a three-center two-electron pi-bond system. Compounds 1 and 2 are the first acyclic germylones containing each one germanium atom and two cAAC: molecules. EPR measurements on compounds 1 and 2 confirmed the singlet spin ground state. DFT calculations on 1/2 revealed that the singlet ground state is more stable by similar to 16 to 18 kcal mol(-1) than that of the triplet state. First and second proton affinity values were theoretically calculated to be of 265.8 (1)/267.1 (2) and 180.4 (1)/183.8 (2) kcal mol(-1), respectively. Further calculations, which were performed at different levels suggest a singlet diradicaloid character of 1 and 2. The TD-DFT calculations exhibit an absorption band at similar to 655 nm in n-hexane solution that originates from the diradicaloid character of germylones 1 and 2.