Anionic Siliconoids from Zintl Phases: R3 Si9 - with Six and R2 Si9 2- with Seven Unsubstituted Exposed Silicon Cluster Atoms (R=Si(tBu)2 H).
Anionic Siliconoids from Zintl Phases: R3 Si9 - with Six and R2 Si9 2- with Seven Unsubstituted Exposed Silicon Cluster Atoms (R=Si(tBu)2 H).
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DOI：
10.1002/chem.201805442
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发表时间：
2018-12
期刊：
影响因子：
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通讯作者：
L. J. Schiegerl;A. Karttunen;W. Klein;T. Fässler
中科院分区：
文献类型：
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作者：
L. J. Schiegerl;A. Karttunen;W. Klein;T. Fässler
中性和阴离子硅团簇是研究体硅表面的重要模型体系。25年来，人们一直提出从二元碱金属硅化物相形成它们，但实验上从未实现。本文首次报道了硅化物的甲硅烷基化，得到具有最高已知无配体硅原子数的阴离子硅化物（Si（tBu）2 H）3Si 9-（1a）和（Si（tBu）2 H）2Si 9 2-（2a）。新阴离子是在K12 Si 17/NH3（liq.）和Si（tBu）2HCl/THF。电喷雾电离光谱法和1H、13 C、29 Si以及29 Si-HMBC（杂原子多重键相关）NMR光谱法证实了根据计算的NMR位移，在形成Ia的情况下三个甲硅烷基连接在[Si 9]4-簇上。在晶体生长过程中，形成了硅化物双阴离子2a。单晶X-射线结构测定表明，两个硅基连接到三角形Si 9团簇核心，揭示了七个未取代的暴露的硅团簇原子，具有半球形配位。负电荷-1和-2分别在1 a和2 a的六个和七个硅原子上离域。
Neutral and anionic silicon clusters (siliconoids) are regarded as important model systems for bulk silicon surfaces. For 25 years their formation from binary alkali metal silicide phases has been proposed, but experimentally never realized. Herein the silylation of a silicide, leading to the anionic siliconoids (Si(tBu)2 H)3 Si9 - (1 a) and (Si(tBu)2 H)2 Si9 2- (2 a) with the highest known number of ligand-free silicon atoms is reported for the first time. The new anions are obtained in a one-step reaction of K12 Si17 /NH3 (liq.) and Si(tBu)2 HCl/THF. Electrospray ionization spectrometry and 1 H, 13 C, 29 Si, as well as 29 Si-HMBC (heteronuclear multiple bond correlation) NMR spectroscopy, confirm the attachment of three silyl groups at a [Si9 ]4- cluster under formation of 1 a, in accordance with calculated NMR shifts. During crystal growth the siliconoid di-anion 2 a is formed. The single-crystal X-ray structure determination reveals that two silyl groups are connected to the deltahedral Si9 cluster core, revealing seven unsubstituted exposed silicon cluster atoms with a hemispheroidal coordination. The negative charges -1 and -2 are delocalized over the six and seven siliconoid Si atoms in 1 a and 2 a, respectively.