稀土-后过渡异核金属烷基簇的构筑与协同直接活化惰性C-H键反应研究

Heterobimetallic cluster containing rare-earth metal (Ln) and late-transition metal (TM), a combinative motif (Ln-TM) of a soft Lewis acidic site and a hard Lewis acidic site, is expected to provide some unique synergistic effect between two different metallic sites, which is different from that of monometallic complex or homometallic cluster. In view of this synergistic effect, Ln-Tm cluster is able to achieve the greatest reactivity of Ln and TM through modifying their own weakness in physical and chemical properties each other. However, up to date, Ln-TM cluster was not extensively applied in the field of catalyst chemistry, mainly due to the difficulties in synthetic method and structural defects of most Ln-TM clusters reported. In this project, we plan to construct (N-P)mLn-TM(Rn) cluster supported by phosphinoamide (N-P), a bifunctional bidentate ligand, based on the Soft Hard Acid Base Rule for the first time, and explore its bimetallic coorperative reactivity for inert C-H bond activation. Design and synthesis of Ln-TM cluster, structure analysis of Ln-TM cluster, assembling rule of Ln complex and TM complex, multi-metallic reactivity of Ln-TM cluster, synergism response of Ln-TM cluster to Metals (Ln and TM) or N-P ligand will be attributed. It is expected that this study not only erich the substantial structures in coordination chemistry, but also is conductive to exploring the high-efficiency catalyst based on Ln-TM cluster and new synergistic reactive system catalyzed by Ln-TM cluster. In addition, it is of theoretical and potential importance to comprehensive utilization of rare earth metals resource and sustainable development of rare earch metals industry in our country.

稀土-后过渡双金属簇（Ln-TM）具有独特的软、硬Lewis酸中心，可显示出不同于单金属或同核金属簇催化剂的异核双金属协同效应，这种协同能够发挥两类金属的优势，实现各自物理、化学性质的优缺点互补。然而，Ln-TM簇合成上的困难和现有大多数Ln-TM簇的结构缺陷制约了其在催化领域内的应用。本项目拟采用双齿双功能单膦胺（N-P）配体，依据软硬酸碱理论，突破合成瓶颈，首次构建稀土-后过渡双金属烷基簇(N-P)mLn-TM(Rn)，并探索其协同活化转化惰性C-H键反应性能。研究内容包括：异核金属簇的设计合成、成键方式及簇组装规律分析，异核协同催化、活化反应研究，异核协同效应与金属类型、配体之间的依存关系等。本研究不仅能够丰富和发展物质结构，而且对于开发Ln-TM高效催化剂、Ln-TM新型协同催化体系以及促进我国稀土资源的综合利用和可持续性发展等方面具有潜在应用和理论意义。

探索具有独特的物理、化学性质的新型化合物的合成是化学领域内的主要研究方向之一。稀土-后过渡双金属簇具有软、硬Lewis酸活性中心，预测可显示出不同于单金属中心和同核金属簇的独特异核双金属协同效应，发挥两类金属的优势，实现各自物理、化学性质的优缺点互补。但稀土和后过渡金属自身性质的极大差异带来了双金属簇合成上的困难。本项目采用具有独特的软、硬Lewis碱中心的单膦胺配体作为连接基团，依据软硬酸碱理论，系统开展了稀土-后过渡双金属簇的合成及C-H键活化性能的研究。取得的主要研究成果如下：（1）首次建立了一个单膦胺稀土双烷基化合物的制备方法。利用盐析反应或烷基消除反应成功制备了19个单膦胺稀土化合物，并通过核磁和X-Ray单晶衍射进行了结构表征。（2）系统探索了单膦胺稀土-后过渡双金属簇的合成反应条件，首次建立了一个稀土-铂双金属簇的制备体系，发现了独特的异核协同活化惰性C-H键和Ph-Cl键现象。（3）构建了一个单膦胺稀土阳离子高效催化吡啶惰性C-H键（o-C(sp2)-H和苄基o-C(sp3)-H键）和a-烯烃的加成反应体系。（4）系统开展了单膦胺稀土阳离子催化1,5-二烯和吡啶惰性C-H键（o-C(sp2)-H和苄基o-C(sp3)-H键）直接环化反应及机理研究，实现了首例催化非共轭二烯和惰性C-H键碳环化反应，为制备复杂五元碳环骨架衍生化分子提供了一个原子经济和步骤经济的新方法。（5）系统开展了阳离子稀土催化1,5-和1,6-非共轭二烯芳氢环化反应及机理研究，建立了一个制备五（六）元碳环体系芳烃衍生化分子的绿色合成途径。此方法不仅具有重要的理论参考价值，同时在天然产物合成和生物活性分子以及药物中间体离域有重要的潜在应用。