The elusive silyliumylidene [ClSi:]+ and silathionium [ClSi=S]+ cations stabilized by bis(iminophosphorane) chelate ligand.
The elusive silyliumylidene [ClSi:]+ and silathionium [ClSi=S]+ cations stabilized by bis(iminophosphorane) chelate ligand.
复制标题
难以捉摸的亚硅基[ClSi:]和硅硫鎓[ClSi=S]阳离子由双(亚氨基正膦)螯合配体稳定。
DOI：
10.1002/anie.201205840
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发表时间：
2012
影响因子：
--
通讯作者：
M. Driess
中科院分区：
文献类型：
--
作者：
Y. Xiong;Shenglai Yao;S. Inoue;E. Irran;M. Driess
硅烯是单线态卡宾的硅类似物，是具有双配位二价硅原子的高反应性化合物。母体亚硅基及其带有小有机基团 R 的衍生物 R2SiD 代表反应性中间体，已在气相、稀释溶液和低温冷冻稀有气体基质中进行了研究。同样，二氯甲硅烷基 (DSiCl2) 是一种难以捉摸的二价硅物质，在西门子工艺、硅薄膜的化学气相沉积、元素氯干法蚀刻硅晶片以及硅和二氧化硅界面的等离子蚀刻中发挥着特殊作用。尽管自 1964 年以来人们一直在研究气态 DSiCl2 的合成和反应性，但对其反应性的研究仅限于低温 (77 K) 下的气相和基质隔离系统，因为它在较高温度下容易聚合为 (SiCl2)n。 [3] 自 1994 年以来，供体-受体稳定的概念已非常成功地应用于多种类型的可分离环状和无环硅烯的合成。 Rivard、Robinson 及其各自同事报道了最新进展，包括稳定 H2Si: 配合物的惊人合成。 2009年，Roesky和Filippou的研究小组表明，二卤代甲硅烷基DSiX2（X = Cl，Br）可以被杂环卡宾（NHCs）稳定，形成可分离的NHC！SiX2配合物A（方案1）。后者代表了长期寻找的方便的二卤硅(II)前体。另一个挑战是合成可分离的二价硅阳离子，即亚硅基阳离子（[RSiD]；R = H、卤素、有机基团）。值得注意的是，通过利用合适的热力学和/或动力学稳定，可以合成第一个可分离的亚硅基阳离子RSi（R =五烷基环戊二烯基，b-二酮亚胺），其带有庞大的单价取代基R和额外的供体位点。其他类型的亚甲硅烷基作为通用结构单元和路易斯酸催化剂非常有吸引力。因此，一氯甲硅烷基亚叉[ClSiD]似乎是一种非常有前途的甲硅烷基亚叉前体，因为氯原子可以被合适的亲核基团R取代，从而为其他类型的甲硅烷基亚叉衍生物[RSiD]铺平道路。然而，[ClSiD]只能通过气相合成产生，例如在氦气氛中稀释的SiCl4空心阴极放电，并且只能在非常规实验条件下在气相中通过红外光谱和质谱检测。最近，Reid、Roesky、Stalke 及其各自的同事在中性三齿供体配体存在下，通过路易斯碱介导的 GeCl2 和 SnCl2 自电离合成了阳离子氯甲亚基和氯甲亚基络合物 B（方案 1）。 1996 年，Cooks 和同事报道了双（吡啶）负载的 [ClSiD] 的质谱研究。然而，带有亚氯甲硅烷基阳离子的可分离复合物仍然未知。 B的形成促使我们通过使用双(叶立德)供体配体开发路易斯碱稳定的氯甲硅烷基亚基[ClSiD]。最近，我们发现双（磷叶立德）可以作为稳定高路易斯酸性硅位点的有效供体（参见方案1中的碳环亚硅基C）。在此，我们报道了第一个可分离的由双（亚氨基正膦）螯合物配体 1 稳定的氯硅基亚叉烯物种 2 的合成。此外，还介绍了 2 与元素硫的反应性，从而产生了前所未有的氯硅硫鎓络合物 3（方案 2）。由于两个 N=PnBu3 叶立德部分键合在萘环的位置 1 和 8，中性配体 1 既充当非常强的布朗斯台德碱又充当路易斯碱（方案 2）。因此，处理三氯硅烷方案1。NHC稳定的二卤亚甲硅烷基A、亚氯甲鎓基及其锡类似物B、以及双(磷叶立德)稳定的亚甲硅烷基C。
Silylenes, the silicon analogues of singlet carbenes, are highly reactive compounds with dicoordinate divalent silicon atoms. Parent silylene and its derivatives R2SiD with small organic groups R represent reactive intermediates, which have been investigated in the gas-phase, in diluted solutions, and in frozen rare-gas matrices at low temperatures. Likewise, dichlorosilylene (DSiCl2) is an elusive divalent silicon species, which plays a particular role in the Siemens process, in the chemical vapor deposition of thin silicon films, and in dry etching of silicon wafers by elemental chlorine, as well as in the plasma etching of silicon and silicon dioxide interfaces. Although synthesis and reactivity of gaseous DSiCl2 has been investigated since 1964, studies on its reactivity have been limited to the gas phase and matrix-isolation systems at low temperatures (77 K), because it polymerizes readily to (SiCl2)n at higher temperatures. [3] Since 1994, the concept of donor–acceptor stabilization has been very successfully applied to the synthesis of several types of isolable cyclic and acyclic silylenes. Recent progress includes the striking synthesis of stable H2Si: complexes, reported by Rivard, Robinson, and their respective co-workers. In 2009, the research groups of Roesky and Filippou showed that dihalosilylenes DSiX2 (X = Cl, Br) can be stabilized by Nheterocyclic carbenes (NHCs) to form isolable NHC!SiX2 complexes A (Scheme 1). The latter represent long-sought convenient dihalosilicon(II) precursors. Another challenge is the synthesis of isolable divalent silicon cations, that is, silyliumylidene cations ([RSiD]; R = H, halogen, organo groups). Remarkably, by utilizing suitable thermodynamic and/or kinetic stabilization, the first isolable silyliumylidene cations RSi (R = pentaalkylcyclopentadienyl, b-diketiminate), which bear bulky monovalent substituents R with additional donor sites, could be synthesized. Other types of silyliumylidenes would be very attractive for employment as versatile building blocks and Lewis acid catalysts. Accordingly, monochlorosilyliumylidene [ClSiD] appears to be a very promising silyliumylidene precursor, because the chlorine atom could be replaced by suitable nucleophiles R to pave the way to other types of silyliumylidene derivatives [RSiD]. However, [ClSiD] can only be generated by gas-phase synthesis, for example, by hollow cathode discharge of SiCl4 diluted in a helium atmosphere, and can only be detected by infrared spectroscopy and mass spectrometry in the gas phase under unusual experimental conditions. Very recently, Reid, Roesky, Stalke, and their respective co-workers synthesized the cationic chlorogermyliumylidene and chlorostannyliumylidene complexes B through a Lewis base mediated autoionization of GeCl2 and SnCl2 in the presence of a neutral tridentate donor ligand (Scheme 1). In 1996, Cooks and co-workers reported a mass spectrometry study of bis(pyridine)-supported [ClSiD]. However, an isolable complex that bears the chlorosilyliumylidene cation is still unknown. The formation of B prompted us to develop a Lewis base stabilized chlorosilyliumylidene [ClSiD] by employing a bis(ylide) donor ligand. Recently, we have shown that a bis(phosphorus ylide) can serve as an effective donor to stabilize highly Lewis acidic Si sites (see carbocyclic silylene C in Scheme 1). Herein, we report the synthesis of the first isolable chlorosilyliumylidene species 2 stabilized by the bis(iminophosphorane) chelate ligand 1. Moreover, the reactivity of 2 toward elemental sulfur, which leads to the unprecedented chlorosilathionium complex 3 (Scheme 2), is presented. Because of the two N=PnBu3 ylide moieties, which are bonded at positions 1 and 8 of the naphthalene ring, the neutral ligand 1 behaves both as a very strong Brçnsted and Lewis base (Scheme 2). Thus, treatment of trichlorosilane Scheme 1. NHC-stabilized dihalosilylenes A, chlorogermyliumylidenes and their tin analogues B, and the bis(phosphorus ylide)-stabilized silylenes C.