Synthesis of Novel Chelating N-Heterocyclic Carbenes and Their Heavier Analogues as Tools in Coordination Chemistry

N-杂环卡宾(NHCs)因其在配位/有机金属化学、催化和材料科学中的巨大潜力而引起了世界各国的广泛关注。近年来，稳定的N-杂环硅烯(NHSis)作为NHC的硅类似物，已经不再是实验室中的稀有物质，而是新功能硅化合物的宝贵构建块。特别是，NHSis可以作为低价主族元素和过渡金属的非常有效的sigma给体配体，形成目前未知的和有希望的化学行为的新型配合物。该项目的目标是开发新的NHC和NHSI螯合体系，作为稳定目前未知主基(Si、Ge、Sn、Pb、B、Al、Ga等)的有效支撑配体。和过渡金属(Mn、Fe、Co、Ni等)。复合体。由于中心原子的氧化态异常低，预计这些络合物将显示出特殊的反应活性。由此得到的螯合配体支撑的低价化合物对小分子的活化具有高度的反应性，因此有助于底物的化学转化，否则很难实现。此外，含有硅烯的靶系统，具有至少一个二价硅中心，甚至能够在没有金属存在的情况下促进小分子的活化，并可以导致有机底物的增值偶联产物，例如CO和异氰化物的异构偶联制得酮亚胺。不仅是为了更好地理解，而且最终在预测它们在配位化学中的指导作用的水平上，NHC和NHSI螯合配体的合成和反应模式，相关的Sigma给体系统，如膦，吡啶，甚至那些目前未知的双膦和双亚甲基的合成和反应模式都包括在这项研究中。

N-Heterocyclic carbenes (NHCs) have been attracting worldwide interest because of their considerable potential in coordination/organometallic chemistry, catalysis and materials science. In recent years, stable N-heterocyclic silylenes (NHSis), the silicon analogues of NHCs, are no longer laboratory curiosities but valuable building blocks for new functional silicon compounds. Particularly, NHSis can act as very effective sigma-donor ligands toward low-valent main group elements and transition-metals to form novel types of complexes with currently unknown and promising chemical behavior. The goal of this project is to develop new NHC and NHSi chelate systems that serve as effective supporting ligands for the stabilization of currently unknown main-group (Si, Ge, Sn, Pb, B, Al, Ga, etc.) and transition metal (Mn, Fe, Co, Ni, etc.) complexes. The complexes are expected to show particular reactivities because of the unusual low oxidation states of the central atoms. The resulting chelate ligand supported low-valent compounds are highly reactive with respect to the activation of small molecules and thus useful for chemical transformations of substrates which are otherwise hard to achieve. Moreover, the silylene-containing target systems, featuring at least one divalent silicon center, are even capable to facilitate the activation of small molecules without the presence of a metal (‘metal-free’) and can lead to value-added coupling products of organic substrates such as the heterocoupling of CO and isocyanides to give ketimines. Not only for better understanding but eventually to derive at the level of predicting their steering role in coordination chemistry, the synthesis and reactivity patterns of NHC and NHSi chelate ligands,related sigma-donor systems such as phosphine, pyridine and even those of the currently unknown bis-phosphinidene and bis-borylene moieties are included in this investigation.