Divalent silicon(0) compounds.
Divalent silicon(0) compounds.
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DOI：
10.1002/chem.200802739
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发表时间：
2009-03
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影响因子：
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通讯作者：
Nozomi Takagi;T. Shimizu;G. Frenking
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作者：
Nozomi Takagi;T. Shimizu;G. Frenking
对一系列双配位硅化合物 SiL(2)（其中 L 是五元环物种）的几何结构和电子结构的量子化学计算表明，该分子是二价硅（0）化合物，具有两个 L-->Si 供体-受体键和两个在硅上具有 pi 和 sigma 对称性的孤对金属氧化物。具有L-->Si<-L供体-受体键的双配位硅化合物的分类不仅适用于其中L是N-杂环卡宾的分子，而且还适用于L是环状亚甲硅基的分子。最近合成的“trisilaallene”（S. Ishida, T. Iwamoto, C. Kabuto, M. Kira, Nature 2003, 421, 725），其中心部分的弯曲角为 136.5(o)，写作 Si=Si=Si，可能更适合视为二价硅 (0) 化合物。我们建议将后一种物质命名为“硅酮”，类似于识别二价 Si(II) 化合物的硅烯。这种成键解释解释了理论上预测的第一和第二质子亲和力的大值以及一个和两个 BH(3) 配体的大键解离能的值。计算预测二价硅（0）化合物的第一次质子化发生在π孤对轨道上，产生质子化的硅酮，其配体在中心三配位硅原子处呈金字塔形排列。硅烷SiL(2) 可能是过渡金属化合物的有趣配体。还报告了类似碳化合物的计算结构和成键情况。
Quantum-chemical calculations of the geometries and electronic structures of a series of dicoordinated silicon compounds SiL(2), in which L is a five-membered cyclic species suggest that the molecules are divalent silicon(0) compounds that possess two L-->Si donor-acceptor bonds and two lone-pair MOs with pi and sigma symmetry at silicon. The classification as a dicoordinate silicon compound with L-->Si<--L donor-acceptor bonds applies not only to molecules in which L is an N-heterocyclic carbene but also when L is a cyclic silylene. The recently synthesized "trisilaallene" (S. Ishida, T. Iwamoto, C. Kabuto, M. Kira, Nature 2003, 421, 725), which has a bending angle of 136.5(o) for the central moiety, and which was written as Si=Si=Si, is probably better considered as a divalent silicon(0) compound. We suggest the name silylones for the latter species in analogy to silylenes which identify divalent Si(II) compounds. This bonding interpretation explains the theoretically predicted large values for the first and second proton affinities and for the large bond dissociation energies for one and two BH(3) ligands. The calculations predict that the first protonation of the divalent silicon(0) compounds takes place at the pi lone-pair orbital, which yields protonated silylones that have a pyramidal arrangement of the ligands at the central tricoordinate silicon atom. Silylones SiL(2) could be interesting ligands for transition-metal compounds. The calculated structures and bonding situation of the analogous carbon compounds are also reported.