Source: Science and Technology Daily
Title: Chinese Research Team Successfully Synthesizes Rare Earth Triple Bond Compound
Science and Technology Daily Report (Reporter Zhang Gailun) Rare earth elements are important strategic resources, and their chemical bond properties directly affect the properties, functions, and technical applications of rare earth compounds. Recently, a research team in China has successfully prepared the long-sought-after "research禁区" rare earth triple bond compound, breaking the traditional understanding of the bonding ability of rare earth elements and providing new experimental evidence and theoretical support for the development of rare earth chemical bond theory. The related research results have been recently published in the journal Nature Chemistry.
Rare earth elements include scandium, yttrium, and 15 lanthanide elements, with electronic structures that are extremely complex, special, and diverse. In rare earth compounds, chemical bonds mainly exist in the form of ionic bonds based on electrostatic interactions. Due to the contraction effect of the 4f orbitals and the high energy of the 5d orbitals, rare earth elements have very limited ability to form covalent bonds, especially double and triple bonds. Because of this property, it has been extremely rare to prepare lanthanide rare earth compounds with double bonds, and preparing triple bond compounds has been considered "impossible."
Successfully constructing a stable rare earth triple bond can not only promote the development of the valence bond theory of rare earth elements, but also provide a new path for the design of new rare earth catalysts and the development of advanced functional materials. Recently, the research group led by Chen Ning from Soochow University and the research group led by Li Jun from Tsinghua University collaborated to innovatively use the spatial confinement and protective effects of fullerene molecular cages, and used a modified arc discharge technology to successfully prepare the first rare earth element cerium-carbon triple bond compound embedded in a fullerene, achieving the stable construction of the cerium-carbon triple bond.
X-ray single crystal diffraction analysis showed that the cerium-carbon bond length in this structure highly coincides with the theoretically predicted triple bond length. Through the combined characterization of visible-near infrared absorption spectroscopy and electron paramagnetic resonance spectroscopy, as well as quantum chemistry studies, the team further confirmed that the compound has a closed-shell electronic configuration. The characteristic vibration peak of the cerium-carbon bond observed in the infrared spectrum is consistent with the theoretical simulation results, providing direct evidence for the existence of the rare earth triple bond.
Original article: https://www.toutiao.com/article/7519325993954296331/
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