Are metalloid clusters essential intermediates during the dissolution process of metals in general and, in special, of magnesium during the formation of Grignard Reagents (GR)?

类金属簇是一般金属溶解过程中的重要中间体，特别是格氏试剂 (GR) 形成过程中镁的溶解过程吗？

• 批准号: 324039962
• 负责人: Professor Dr. Hansgeorg Schnöckel
• 金额: --
• 依托单位: Institut für Anorganische Chemie (aoc)
• 依托单位国家: 德国
• 项目类别: Research Grants
• 财政年份: 2016
• 资助国家: 德国
• 起止时间: 2015-12-31 至 2019-12-31
• 项目状态: 已结题
• 来源: https://gepris.dfg.de/gepris/projekt/324039962?language=en
• 关键词: metalloid; clusters; essential; intermediates; during

A prominent example for the dissolution process of a base metal is the formation of the Grignard Reagent (GR): Mg(solid) + RX --> RMgX (X= halide, R= e.g. alkyl). Based on experimental findings MgX/ MgR radicals were postulated in the reaction mixture. This conclusion is reflected in the description within the textbooks up to now: Mg(I) species (e.g. MgCl) are essential intermediates during the formation process of GR. In a recently published article in Chem. Sciences (this result was just presented as a highlight in Nachrichten aus der Chemie) we could show, that not MgX/MgR radicals like postulated so far, but metalloid Mg clusters (e.g. MgnXm, n>m) are essential intermediates during the formation of GR. Because of the very fast reaction of the dissolution process of base metals it was not possible so far to trap an intermediate as a snapshot on this route and to determine the crystal structure. In order to reach this goal, which however will be a dream of future for the direct detection of intermediates during the dissolution process, we decided for an alternative, however experimentally sophisticated, way, which we successfully proceeded for e.g. Al in the last two decades: At about 1000°C MgBr molecules are generated in the gas phase which are subsequently trapped at -196°C and afterwards stored as a metastable solution below -40°C. During the controlled disproportionation and the simultaneous substitution of the halide by the Cp* moiety the metalloid cluster Mg16Cp*8Br4K is formed. This formation process is highly sensitive because the disproportionation reaction of MgBr to solid Mg and MgBr2 is much faster than the substitution reaction. Nevertheless we were now successful via this route to trap the first intermediate between solid Mg and e.g. MgBr2/MgR2: The generated Mg16 cluster has been detected with the help of the ESI procedure in the high resolution FT-ICR spectrum. In the applied project we want to get crystals for the structure determination of the Mg16 and further metalloid clusters for the first time in order to investigate a new territory with the help of synthetic as well as with DFT methods of calculated nanoscaled metalloid Mg clusters as molecular models. The expected results will sustainably modify the description within textbooks of a simply seeming however highly complex but fundamental chemical reaction.

碱金属溶解过程的一个突出的例子是Grignard试剂（GR）：mg（solid） + rx-> rmgx的形成（x =卤化物，r = e.g。烷基）。根据实验发现，在反应混合物中假设MGX/ MGR自由基。该结论反映在迄今为止教科书中的描述中：Mg（i）物种（例如MGCL）是GR形成过程中必不可少的中间体。在最近发表的《化学》中。我们可以表明的是，科学（此结果只是作为Nachrichten Aus der Chemie的亮点显示），而不是像迄今为止发布的MGX/MGR激进分子，而是金属MG MG簇（例如Mgnxm，n> m）是GR形成期间的必不可少的中间体。由于碱金属的溶解过程非常快速，因此无法将中间体作为该路线上的快照并确定晶体结构。为了达到这个目标，这将是在解散过程中直接检测中间体的未来的梦想，我们决定采取一种替代方案，无论实验上的复杂性，我们成功地进行了实验性的方法，例如在过去的二十年中：在大约1000°C下，MGBR分子在气相中产生，随后被捕获在-196°C下，后来被储存为-40°C以下的亚稳态溶液。在受控的不成比例和用CP*部分将卤化物替代的过程中，形成了金属簇Mg16cp* 8BR4K。这种形成过程非常敏感，因为MGBR对固体MG和MGBR2的不成比例反应比取代反应快得多。尽管如此，我们现在通过这条途径取得了成功，以捕获固体毫克和例如之间的第一个中间体。 MGBR2/MGR2：在高分辨率FT-ICR光谱中的ESI过程的帮助下，已检测到生成的MG16群集。在应用项目中，我们希望首次获得MG16和进一步金属簇的结构测定的晶体，以便借助于合成以及计算出的纳米纳米金属MG MG簇作为分子模型来研究新领域。预期的结果将可持续地修改教科书中的描述，即看起来很复杂但基本化的化学反应。