Wang Yi, Liang Jiefeng, Deng Chong, Sun Rong, Fu Peng-Xiang, Wang Bing-Wu, Gao Song, Huang Wenliang
Beijing National Laboratory for Molecular Sciences, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, P. R. China.
Beijing Key Laboratory for Magnetoelectric Materials and Devices, Beijing 100871, P. R. China.
J Am Chem Soc. 2023 Oct 18;145(41):22466-22474. doi: 10.1021/jacs.3c06613. Epub 2023 Sep 22.
Two-electron oxidations are ubiquitous and play a key role in the synthesis and catalysis. For transition metals and actinides, two-electron oxidation often takes place at a single-metal site. However, redox reactions at rare-earth metals have been limited to one-electron processes due to the lack of accessible oxidation states. Despite recent advancements in nontraditional oxidation state chemistry, the low stability of low-valent compounds and large disparity among different oxidation states prevented the implementation of two-electron processes at a single rare-earth metal center. Here we report two-electron oxidations at a cerium(II) center to yield cerium(IV) terminal oxo and imido complexes. A series of cerium(II-IV) complexes supported by a tripodal tris(amido)arene ligand were synthesized and characterized. Experimental and theoretical studies revealed that the cerium(II) complex is best described as a 4f ion stabilized by δ-backdonation to the anchoring arene, while the cerium(IV) oxo and imido complexes exhibit multiple bonding characters. The accomplishment of two-electron oxidations at a single cerium center brings a new facet to molecular rare-earth metal chemistry.
双电子氧化反应无处不在，在合成和催化过程中起着关键作用。对于过渡金属和锕系元素，双电子氧化通常发生在单金属位点。然而，由于缺乏可及的氧化态，稀土金属的氧化还原反应一直局限于单电子过程。尽管非传统氧化态化学最近取得了进展，但低价化合物的低稳定性以及不同氧化态之间的巨大差异阻碍了在单个稀土金属中心实现双电子过程。在此，我们报道了铈（II）中心的双电子氧化反应，生成铈（IV）端基氧代和亚氨基配合物。合成并表征了一系列由三脚架型三（酰胺基）芳烃配体支撑的铈（II - IV）配合物。实验和理论研究表明，铈（II）配合物最好描述为通过向锚定芳烃的δ-反馈配位稳定的4f离子，而铈（IV）氧代和亚氨基配合物表现出多重键合特征。在单个铈中心实现双电子氧化为分子稀土金属化学带来了新的层面。
