Si-H bond activation at {(NHC)₂Ni⁰} leading to hydrido silyl and bis(silyl) complexes: a versatile tool for catalytic Si-H/D exchange, acceptorless dehydrogenative coupling of hydrosilanes, and hydrogenation of disilanes to hydrosilanes.
Si-H bond activation at {(NHC)₂Ni⁰} leading to hydrido silyl and bis(silyl) complexes: a versatile tool for catalytic Si-H/D exchange, acceptorless dehydrogenative coupling of hydrosilanes, and hydrogenation of disilanes to hydrosilanes.
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DOI：
10.1039/c4dt01250j
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发表时间：
2014-06
影响因子：
4
通讯作者：
D. Schmidt;T. Zell;T. Schaub;U. Radius
中科院分区：
文献类型：
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作者：
D. Schmidt;T. Zell;T. Schaub;U. Radius
报道了镍（0）配合物[Ni_2（iPr_2 Im）_4（COD）]（1）（iPr_2 Im = 1，3-二异丙基咪唑啉-2-亚基）在化学计量和催化反应中对氢化硅烷的独特反应性。通过1与含氢硅烷H（n）SiR（4-n）的化学计量反应，合成了一系列镍双硅基配合物cis-[Ni（iPr 2 Im）2（H）（SiH（n-1）R（4-n））]（n = 1，2）和镍双硅基配合物cis-[Ni（iPr 2 Im）2（SiH（n-1）R（4-n））2]（n = 1，2，3），并通过X射线衍射和光谱方法对其进行了表征.这些双甲硅烷基络合物是其中完全氧化加成步骤受阻的实例。由于剩余的Si-H相互作用，它们具有非常短的Si-H距离，并且在溶液中具有独特的动力学行为。顺式-[Ni（iPr 2 Im）2（H）（SiMePh 2）]（cis-5）在室温下的溶液中显示NHC配体的动态位置交换，与C6 D 6的H-D交换得到氘化物配合物cis-[Ni（iPr 2 Im）2（D）（SiMePh 2）]（cis-5-D），并且在升高的温度下不可逆地异构化为反式-[Ni（iPr 2 Im）2（D）（SiMePh 2）]（trans-5-D）。与空间要求较低的硅烷反应得到顺式构型的双（甲硅烷基）配合物，伴随着释放二氢。这些配合物显示，类似于双甲硅烷基配合物，有趣的是短的Si-Si距离。络合物1与4 eq. HSi（OEt）3，与本研究中使用的所有其他硅烷相比，得到反式构型的双（甲硅烷基）配合物trans-[Ni（iPr 2 Im）2Ni（Si（OEt）3）2]（trans-12）。在升高的温度下，将两当量的Ph 2SiH 2加入到1中导致形成双核配合物[{（iPr 2 Im）Ni-μ（2）-（HSiPh 2）}2]（6）。这种抗磁性的形式Ni（I）配合物在固态下表现出长的Ni-Ni键，如通过X射线衍射所确定的。富电子{Ni（iPr 2 Im）2}配合物片段活化Si-H键的能力被应用于以C6 D 6作为方便的氘源的Et 3Si-H到Et 3Si-D的氘代反应中。此外，我们表明1作为催化剂，用于Ph 2SiH 2到相应的乙硅烷Ph 2 HSi-SiHPh 2和丙硅烷Ph 2 HSi-Si（Ph）2-SiHPh 2的无受体双偶联，以及PhSiH 3的偶联，得到具有高多分散性的环状和线性聚硅烷的混合物（M（w）= 1119; M（n）= 924; M（w）/M（n）= 1.2）。1的能力，以催化正式的逆反应，以及证明由氢化的乙硅烷。将二硅烷Ph 2 MeSi-SiMePh 2和PhMe 2Si-SiMe 2 Ph分别氢化成相应的氢硅烷Ph 2 MeSi-H和PhMe 2Si-H在1存在下在非常温和的条件（室温，1.8巴H2压力）下有效地进行。
The unique reactivity of the nickel(0) complex [Ni2(iPr2Im)4(COD)] (1) (iPr2Im = 1,3-di-isopropyl-imidazolin-2-ylidene) towards hydrosilanes in stoichiometric and catalytic reactions is reported. A series of nickel hydrido silyl complexes cis-[Ni(iPr2Im)2(H)(SiH(n-1)R(4-n))] (n = 1, 2) and nickel bis(silyl) complexes cis-[Ni(iPr2Im)2(SiH(n-1)R(4-n))2] (n = 1, 2, 3) were synthesized by stoichiometric reactions of 1 with hydrosilanes H(n)SiR(4-n), and fully characterized by X-ray diffraction and spectroscopic methods. These hydrido silyl complexes are examples where the full oxidative addition step is hindered. They have, as a result of the remaining Si-H interactions, remarkably short Si-H distances and feature a unique dynamic behavior in solution. Cis-[Ni(iPr2Im)2(H)(SiMePh2)] (cis-5) shows in solution at room temperature a dynamic site exchange of the NHC ligands, H-D exchange with C6D6 to give the deuteride complex cis-[Ni(iPr2Im)2(D)(SiMePh2)] (cis-5-D), and at elevated temperatures an irreversible isomerization to trans-[Ni(iPr2Im)2(D)(SiMePh2)] (trans-5-D). Reactions with sterically less demanding silanes give cis-configured bis(silyl) complexes accompanied by the release of dihydrogen. These complexes display, similarly to the hydrido silyl complexes, interestingly short Si-Si distances. Complex 1 reacts with 4 eq. HSi(OEt)3, in contrast to all the other silanes used in this study, to give the trans-configured bis(silyl) complex trans-[Ni(iPr2Im)2Ni(Si(OEt)3)2] (trans-12). The addition of two equivalents of Ph2SiH2 to 1 results, at elevated temperatures, in the formation of the dinuclear complex [{(iPr2Im)Ni-μ(2)-(HSiPh2)}2] (6). This diamagnetic, formal Ni(I) complex exhibits a long Ni-Ni bond in the solid state, as established by X-ray diffraction. The capability of the electron rich {Ni(iPr2Im)2} complex fragment to activate Si-H bonds was applied catalytically in the deuteration of Et3Si-H to Et3Si-D employing C6D6 as a convenient deuterium source. Furthermore, we show that 1 serves as a catalyst for the acceptorless dehydrogenative coupling of Ph2SiH2 to the corresponding disilane Ph2HSi-SiHPh2 and trisilane Ph2HSi-Si(Ph)2-SiHPh2, and the coupling of PhSiH3 to give a mixture of cyclic and linear polysilanes with high polydispersity (M(w) = 1119; M(n) = 924; M(w)/M(n) = 1.2). The capability of 1 to catalyze the formal reverse reaction as well is demonstrated by the hydrogenation of disilanes. The hydrogenation of the disilanes Ph2MeSi-SiMePh2 and PhMe2Si-SiMe2Ph to the corresponding hydrosilanes Ph2MeSi-H and PhMe2Si-H, respectively, proceeds effectively in the presence of 1 under very mild conditions (room temperature, 1.8 bar H2 pressure).