Ultrashort metal-metal distances and extreme bond orders

在第一个支助期间，对三个方面进行了调查。Cr-Cr五重键的反应活性含有极高键级（键级> 4）的稳定分子是最近才发现的。因此，现在可以研究它们的反应性，这样我们就能够更好地理解这些键。我们的贡献在世界范围内的铬-铬五重键反应性领域的最新技术水平占主导地位。最近，在沉默了30年之后，用具有形式五重键的铬络合物获得了短金属-金属距离的新记录。合理的配体设计是关键。我们开展的工作决定了该领域的最新技术水平。在第一阶段的支持，我们可以分离出一个化合物的金属-金属距离类似于最长的C-C键（1.706和1.704 <$）。钼和钨的键级> 4钼和钨络合物更适合形成高（有效）键级。因此，我们的目标是将铬化学转移到钼，并最终转移到钨。同时，Tsai集团决定了钼的最新技术水平。钨化合物是未知的。我们可以在第一阶段的支助中找到获得这些化合物的途径。完成五重键反应性研究B.初级活化产物的反应性研究由Cr-Cr五重键的底物（或元素）反应得到的许多产物本身就是反应性很强的有机金属化合物。它们的反应活性，特别是在催化反应中的反应活性，建议进行研究。五重或六重键的钨配合物键级> 4的钨配合物是第二阶段支持的对象。不稳定的M2分子（M = Cr，Mo和W）的理论工作，物种，只能被隔离在一个惰性的矩阵，给出了有效的键级为6的Mo 2和W2。Cr2的特征在于相关的s-和d-轨道的强尺寸失配。因此，只有弱结合相互作用是部分可能的。它们导致低有效键序。我们计划找到一种获得具有五重（和/或六重）键的W配合物的方法。高键级钨化合物反应活性的研究

Three aspects have been investigated during the first period of support.1. The reactivity of Cr-Cr quintuple bondsStable molecules that contain extremely high bond orders (bond orders > 4) were found only recently. Thus, it is now possible to investigate their reactivity and by doing so we are enabled to understand such bonds better. Our contributions dominate the state of the art in the field of Cr-Cr quintuple bond reactivity worldwide.2. Ultra-short metal-metal distancesRecently, after 30 years of silence new records in terms of short metal-metal distances were obtained with chromium complexes having a formal quintuple bond. Rational ligand design is the key. Work carried our by us determines the state of the art in that field. During the first period of support, we could isolate a compound with a metal-metal distance similar to that of the longest C-C bond (1.706 and 1.704 Å, respectively).3. Bond orders > 4 for molybdenum and tungstenMolybdenum and tungsten complexes are better suited to form high (effective) bond orders. Accordingly, we aimed for transferring the chromium chemistry towards molybdenum and eventually towards tungsten. The state of the art for molybdenum is meanwhile determined by the Tsai group. Tungsten compounds are unknown. We could find an access to such compounds in the first period of support.The following aims have been defined for the second period of researchA. Finalization of the quintuple bond reactivity studiesB. Investigation of the reactivity of the primary activation productsMany products obtained by reacting substrates (or elements) with Cr-Cr quintuple bonds are themselves rather reactive organometallic compounds. Their reactivity especially in catalytic reactions is proposed to be investigated.C. Tungsten complexes with quintuple or sixtuple bondsTungsten complexes having bond orders > 4 are subject of the second period of support. Theoretical work on the instable M2 molecules (M = Cr, Mo and W), species that could only be isolated in an inert matrix, gave effective bond orders of six for Mo2 and W2. Cr2 is characterized by a strong size mismatch of the relevant s- and d-orbitals. Thus, only weakly binding interactions are partially possible. They lead to a low effective bond order. We plan to find an access to W complexes having quintuple (and/or sixtuple) bonds.D. Investigations of the reactivity of tungsten compounds having unusual high bond orders