CarBoRu - Anionic Carbenes and Borylanions: Tuning the properties of ruthenium complexes in olefin metathesis

N-杂环卡宾(NHCs)在金属有机催化领域有着重要的影响。由于它们具有很强的Sigma-给体性质，它们能够在大多数催化循环中削弱M-L键与其他Sigma结合的共配体的转位(反式影响)，并更好地稳定低配位活性物种。当NHC结构被赋予负电荷时，这些效应甚至有望得到增强，负电荷提供阴离子卡宾或硼阴离子(基于碳原子C和B-的等电子关系)。利用这一最新的概念，这一建议的作者已经展示了Au、Ir和Pd催化的高活性体系的例子。鉴于Ru催化的烯烃歧化反应对C=C键形成的重要性和广泛的范围，通过引入-1电荷来调整催化剂的策略将在此基础上扩展到Ru催化的歧化反应。

N-heterocyclic carbenes (NHCs) exerted a strong impact on the area of organometallic catalysis. Due to their strong sigma-donor character they are capable of weakening the M-L bond to other sigma-bound co-ligands in trans-position (trans-influence) and better stabilize low-coordinate active species, which are formed in most catalytic cycles. These effects are even expected to be enhanced when the NHC architectures are endowed with negative charges, which either affords anionic carbenes or boryl anions (based on the isoelectronic relationship of a carbon atom C to B-). Employing this very recent concept, the authors of this proposal have demonstrated examples of Au-, Ir- and Pd-catalyzed systems of high activity. In view of the importance and the wide scope of Ru-catalyzed olefin metathesis for C=C bond formations, the strategy of catalyst tuning by the introduction of -1 charges will be expanded to Ru-catalyzed cmetathesis based on this proposal.