Li Qiao-Zhi, Zheng Jia-Jia, He Ling, Nagase Shigeru, Zhao Xiang
Institute for Chemical Physics and Department of Chemistry, School of Science, State Key Laboratory of Electrical Insulation and Power Equipment, Xi'an Jiaotong University , Xi'an 710049, China.
Fukui Institute for Fundamental Chemistry, Kyoto University , Kyoto 606-8103, Japan.
Inorg Chem. 2016 Aug 1;55(15):7667-75. doi: 10.1021/acs.inorgchem.6b01134. Epub 2016 Jul 18.
Carbon cages in endohedral and exohedral fullerene derivatives are usually different. A recent report suggested that chlorofullerene C66Cl10:Cs and endohedral metallofullerene (EMF) Sc2@C66 shared the same cage (#4348)C66:C2v, while it was denied by the definitive characterization of Sc2@C66, which actually possesses the (#4059)C66:C2v isomer. Here, we show that a (#4348)C66:C2v cage with a double hexagon-condensed pentalene (DHCP) moiety, which was captured by exohedral chlorination, is also capable of being stabilized by encapsulating tri- or divalent monometal (M) species. On the basis of density functional theory calculations combined with statistical mechanics analyses, (#4348)C66:C2v-based mono-EMFs M@C2v(4348)-C66 (M = Tb, La, Y, and Yb) were demonstrated to be the most stable and predominant isomers at the fullerene formation temperature region, while another chlorinated cage (#4169)C66:Cs, featured with triple sequentially fused pentagon (TSFP) moiety, is less favorable to be obtained in the form of EMFs, although these two cages can be interconverted by a simple Stone-Wales transformation. The superiority of M@C2v(4348)-C66 over M@Cs(4169)-C66 comes from the stronger interaction of M-DHCP over that of M-TSFP in both ionic and covalent bonding aspects. In addition, size-selective complexation of host [n]cycloparaphenylene ([n]CPP) and Tb@C2v(4348)-C66 was simulated, showing that [10]CPP exhibits the best affinity toward Tb@C66, which provides a new opportunity for isolation and characterization of C66-based mono-EMFs.
内嵌富勒烯和外嵌富勒烯衍生物中的碳笼通常不同。最近的一份报告表明，氯代富勒烯C66Cl10:Cs和内嵌金属富勒烯（EMF）Sc2@C66共享相同的笼（#4348）C66:C2v，但Sc2@C66的确定性表征否定了这一点，实际上它具有（#4059）C66:C2v异构体。在这里，我们表明，通过外嵌氯化捕获的具有双六边形稠合戊搭烯（DHCP）部分的（#4348）C66:C2v笼，也能够通过封装三价或二价单金属（M）物种而稳定下来。基于密度泛函理论计算并结合统计力学分析，结果表明，基于（#4348）C66:C2v的单内嵌金属富勒烯M@C2v(4348)-C66（M = Tb、La、Y和Yb）在富勒烯形成温度区域是最稳定和最主要的异构体，而另一种具有三重顺序稠合五边形（TSFP）部分的氯化笼（#4169）C66:Cs，虽然这两个笼可以通过简单的斯通-威尔士变换相互转化，但以EMF形式获得的可能性较小。M@C2v(4348)-C66相对于M@Cs(4169)-C66的优势在于，在离子键和共价键方面，M-DHCP的相互作用比M-TSFP更强。此外，模拟了主体[n]环对亚苯基（[n]CPP）与Tb@C2v(4348)-C66的尺寸选择性络合，结果表明，[10]CPP对Tb@C66表现出最佳亲和力，这为基于C66的单内嵌金属富勒烯的分离和表征提供了新的机会。
