Relative stabilities in a metallofullerene series: Z@C76 (Z=Sc, Y, La)

Relative stabilities in a metallofullerene series: Z@C76 (Z=Sc, Y, La)

鄭明雯(Jheng Ming Wun)

指導教授 ： 李錫隆

國立中正大學/理學院/化學暨生物化學系/碩士(2014年)

摘要

這篇論文主要研究C76之內嵌金屬富勒烯以及其空的碳籠穩定性。為了形成內嵌金屬富勒烯我們可知其金屬與碳原子之間的交互作用力扮演著極為重要的角色。因此我們計算了Sc@C76, Y@C76, 和La@C76 這一系列的富勒烯的穩定性，C76總共有兩個對稱性滿足孤立五角規則，其對稱性分別為Td 和D2；而另一個是對稱性為C2v不符合孤立五角規則，其具有兩個相鄰的五圓環結構。同時我們也計算了內嵌兩顆金屬在碳籠內的穩定性，其對稱性為Cs: Z2@Cs(17490)-C76 (Z = Sc, Y, La)，Cs同時也不符合孤立五角規則，並且具有兩對相鄰的五圓環結構。透過相對能量的計算，我們發現在任何對稱性下內嵌La金屬的富勒烯是最穩定。

關鍵字

金屬富勒烯

並列摘要

This report deals with an important feature of metallofullerenes - the fact that the most stable empty carbon-cage isomers are generally different from the carbon cages employed with the most stable metalofullerenes. The stability reversal is roted in the interactions between the carbon cage and the encapsulated metal which lead to a strong charge transfer from the metal to the cage. In order to study the stability relationships, the encapsulation potential-energy changes for Sc@C76, Y@C76, and La@C76 series are computed. There are only two IPR (isolated pentagon rule) isomers for C76-cage (Td and D2 symmetry). In this work, computations for the Z@C76 (Z = Sc, Y, La) metal encapsulations into the IPR isomers as well as non-IPR C2v symmetry C76 cage (which has two adjacent pentagon rings or one pair of fused pentagons) are reported. We also compute the Z2@Cs(17490)-C76 (Z = Sc, Y, La) series based on a very recently observed non-IPR structure which contains even two pairs of the adjacent pentagons. The results can be well related to the ionization potentials of the free metal atoms, thus also rationalized, and the computations also offer an explanation of the metallofullerene stability islands in the periodic table of elements.

並列關鍵字

metallofullerene

參考文獻

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