Single crystal structures and theoretical calculations of uranium endohedral metallofullerenes (U@C(2n) , 2n = 74, 82) show cage isomer dependent oxidation states for U.
Single crystal structures and theoretical calculations of uranium endohedral metallofullerenes (U@C(2n) , 2n = 74, 82) show cage isomer dependent oxidation states for U.
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铀内嵌金属富勒烯（U@C（2n），2n = 74，82）的单晶结构和理论计算表明，U的氧化态与笼型异构体有关。
DOI：
10.1039/c7sc01711a
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发表时间：
2017-08-01
期刊：
影响因子：
8.4
通讯作者：
Echegoyen L
中科院分区：
文献类型：
--
作者：
Cai W;Morales-Martínez R;Zhang X;Najera D;Romero EL;Metta-Magaña A;Rodríguez-Fortea A;Fortier S;Chen N;Poblet JM;Echegoyen L
第一个X射线结构和金属氧化态依赖于笼异构的U-EMF。电荷转移是所有内嵌单金属富勒烯的普遍现象。自从1991年发现第一个内嵌金属富勒烯（EMF）La@C82以来，人们一直观察到，无论笼的大小如何，给定封装金属的氧化态总是相同的。没有晶体学数据存在任何早期的锕系元素的内面体和鲜为人知的氧化态的少数化合物已被报道。本文报道了三种铀金属富勒烯（U@ D3 h-C74，U@C2（5）-C82和U@C2v（9）-C82）的X射线结构，为U的笼型异构体依赖的电荷转移态提供了理论依据。DFT计算结果表明，U@ D3 h-C74和U@C2（5）-C82具有四价电子构型，对应于U4+@ D3 h-C744-和U4+@C2（5）-C824-。令人惊讶的是，异构体U@C2v（9）-C82具有对应于U3+@C2v（9）-C823-的三价电子构型。这是铀EMF的第一个X射线晶体结构，这是第一次观察到金属氧化态对单EMF碳笼异构性的依赖。
First X-ray structures and metal oxidation state dependence on cage isomerism for U-EMFs. Charge transfer is a general phenomenon observed for all endohedral mono-metallofullerenes. Since the detection of the first endohedral metallofullerene (EMF), La@C82, in 1991, it has always been observed that the oxidation state of a given encapsulated metal is always the same, regardless of the cage size. No crystallographic data exist for any early actinide endohedrals and little is known about the oxidation states for the few compounds that have been reported. Here we report the X-ray structures of three uranium metallofullerenes, U@D3h-C74, U@C2(5)-C82 and U@C2v(9)-C82, and provide theoretical evidence for cage isomer dependent charge transfer states for U. Results from DFT calculations show that U@D3h-C74 and U@C2(5)-C82 have tetravalent electronic configurations corresponding to U4+@D3h-C744– and U4+@C2(5)-C824–. Surprisingly, the isomeric U@C2v(9)-C82 has a trivalent electronic configuration corresponding to U3+@C2v(9)-C823–. These are the first X-ray crystallographic structures of uranium EMFs and this is first observation of metal oxidation state dependence on carbon cage isomerism for mono-EMFs.