NHC-Stabilized Silagermenylidene: A Heavier Analogue of Vinylidene
NHC-Stabilized Silagermenylidene: A Heavier Analogue of Vinylidene
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DOI：
10.1002/anie.201306780
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发表时间：
2013-11-11
影响因子：
16.6
通讯作者：
Scheschkewitz, David
中科院分区：
文献类型：
--
作者：
Jana, Anukul;Huch, Volker;Scheschkewitz, David
乙炔(I)及其异构化为亚乙烯(II)的化学长期以来一直是理论化学家们热衷研究的话题，[1]很快引起了人们对相应的较重同系物III和IV(方案1)的兴趣。[2]到目前为止，还没有分离出游离的亚乙烯或其较重的类似物。[3a-c]母体亚乙烯(II)在基质实验中尚未被检测到。首次报道了二苯基亚甲基过渡金属络合物的结构表征，它们是由二苯基乙烯酮和五酮铁反应得到的。[4A]同时，亚乙叉过渡金属络合物已作为催化剂获得了一些突出的地位，特别是在烯烃和炔烃的歧化反应中。然而，在这两种情况下，都没有观察到对应的IV型二硅亚叉或二亚甲叉的异构化。相反，在异核H_2SiGe势能面上的理论计算预测了Siagermenylidene(H_2Si=Ged)比Silagermyne(HSI GeH)和Germasilenylidene(H_2Ge=Sid)在能量上更有利。[7]相对于H_2Ge=Sid，H_2Si=Ge=Sid的稳定性归因于Ge上更分散的轨道，比硅更容易容纳单个电子对。
The chemistry of acetylene (I) and its isomerization to vinylidene (II) has been an intensely researched topic for theoretical chemists for a long time,[1] which soon prompted interest in the corresponding heavier congeners III and IV (Scheme 1).[2] To date, neither free vinylidene or its heavier analogues have been isolated.[3a–c] The parent vinylidene (II) has been detected in matrix experiments.[3d–f] In 1966, Mills et al. reported the first structurally characterized transitionmetal complexes of diphenylvinylidene, which were obtained from the reaction of diphenylketene and ironpentacarbonyl.[4a] In the meantime, vinylidene transition-metal complexes have acquired some prominence as catalysts, in particular in alkene and alkyne metathesis.[4b–d] Substituted examples of disilynes (III, M= M’= Si)[5] and digermynes (III, M= M’= Ge)[6] have been isolated as the heavier analogues of alkynes. In neither case, however, was isomerization to the corresponding disilenylidene or digermenylidene of type IV observed. In contrast, theoretical calculations on the heteronuclear H2SiGe potential energy surface predict that silagermenylidene (H2Si= GeD) is energetically favored over both silagermyne (HSi GeH) and germasilenylidene (H2Ge= SiD).[7] The stability of H2Si= GeD relative to H2Ge= SiD is attributed to the more diffuse orbitals at germanium that accommodate a lone electron pair more easily than in the case of silicon.