锕系金属(铀和锔)内嵌硼球烯的理论研究

Theoretical Studies on Actinides(U and Cm)Endohedral Borospherenes

最近发现的全硼富勒烯(硼球烯,D_(2d) B^(-/0)_(40)),开启了硼球烯化学研究的新篇章。类似于富勒烯,金属掺杂也是硼球烯修饰和功能化重要途径。本工作采用密度泛函理论预测了一系列锕系金属掺杂硼球烯[An@B_(39)]^(n+)(An=U,n=3;An=Cm,n=2)。理论计算表明,这些硼球烯均为稳定的金属内嵌硼球烯,其中[U@B_(39)]^(3+)的能量最低,结构具有C_(3)对称性,而[Cm@B_(39)]^(2+)为C_(1)结构。成键性质分析表明,[U@B_(39)]^(3+)和[Cm@B_(39)]^(2+)均存在σ和π离域键。另外[An@B_(39)]^(n+)中U-B键的共价相互作用强于Cm-B键,且[U@B_(39)]^(3+)较[Cm@B_(39)]^(2+)更稳定。因此,An-B键的共价特征对于这些锕系金属内嵌硼球烯的形成是必不可少的。本工作扩展了硼球烯体系,并为新型稳定金属内嵌硼球烯的设计提供了理论线索。

The recently discovered all-boron fullerene(D_(2d) B^(-/0)_(40))opened a new chapter in borospherene chemistry.Similar to fullerenes,metal doping is also an important way for modification and functionalization of borospherenes.This work predicts a series of stable actinide metal-doped borospherenes[An@B_(39)]^(n+)(An=U,n=3;An=Cm,n=2)by using density functional theory.Theoretical calculations show that these borospherenes are all endohedral borospherenes,among which the lowest energy structures of[U@B_(39)]^(3+)has C_(3) symmetry,while[Cm@B_(39)]^(2+)is a C_(1) structure.Bonding nature analysis shows that delocalizedσandπbonds exist in[U@B_(39)]^(3+)and[Cm@B_(39)]^(2+).In addition,the covalent interaction of the U-B bond in[An@B_(39)]^(n+)is stronger than that of the Cm-B bond.Therefore,the covalency in the An-B bonds may be essential for the formation of these metal-doped borospherenes.This work expands the borospherenes system and provides theoretical clues for the design of novel stable metal endohedral borospherenes.