Theoretical Sstudy On The Endohedral Of Boron In Actinide Metals

The use of boron-containing compounds as medicines has a long history.Due to the electronic defect nature of boron,the formation of its chemical bonds is very complicated,and the formed compound structure is very rich.The discovery of all-boron fullerene（borospherenes）opened a new chapter in the study of borospherenes chemistry.Similar to fullerenes,metal embedding is an important way for the functionalization of borospherenes.In the reported work,in addition to alkaline earth metals,there are transition metals and lanthanide metals that can be embedded inborospherenes.However,there is little research work on actinide-based metal embedded borospherenes.In the past few decades,people have gradually become interested in the electronic and structural evolution of boron clusters.The publication of research results on boron fullerenes made it possible to embed boron spheres.Many atoms are embedded in borospherenes,so the endohedral borospherenes also has very rich characteristics.In the reported work,in addition to alkaline earth metals,there are transition metals and lanthanide metals as metals used in endohedral borospherenes.There are relatively few studies on actinide metal-doped borospherenes.Based on this,based on the density functional theory,this article carried out the chemical modification of different actinide-based metal-doped B^-₃₉borospherenes,and conducted a series of in-depth analysis on the actinide-doped borospherenes.The research is mainly divided into the following two parts:1.Actinide metal（actinium and thorium）doped chiral boron cageProve the feasibility of a series of actinides embedded borospherenes[An@B₃₉]ⁿ⁺（An=Ac,Cf;n=0,2;An=Th;n=0,3）at the level of DFT-PBE0.It has been proved that the neutral and charged actinium metal and thorium metal embedded chiral borospherenes(Ac@B₃₉,[Ac@B₃₉]²⁺and Th@B₃₉,[Th@B₃₉]³⁺)are the most stable structures,similar to the chiral boron atom group B^-₃₉.However,the C₁structures are the global minima for Cf@B₃₉and[Cf@B₃₉]²⁺.According to Ad NDP analysis,[Ac@B₃₉]ⁿ⁺（n=0,2）and[Th@B₃₉]ⁿ⁺（n=0,3）possess delocalizedσandπbonding,and the covalency of Th-B bonding is relatively higher compared to the Ac-B bonding.EDA analysis confirms that metal-ligand bonding in[Th@B₃₉]³⁺has the highest covalent character,and covalent interaction plays a major role in[An@B₃₉]ⁿ⁺.These results are consistent with bond order,QTAIM,and MO analyses.Thermodynamic analysis shows that[An@B₃₉]ⁿ⁺（An=Ac,n=0,2;An=Th,n=0,3）the Th-B₃₉boron clusters show higher formation energies than the corresponding Ac-B₃₉clusters.Besides,in the C₂[An@B₃₉]ⁿ⁺systems,[Th@B₃₉]³⁺has the highest formation energies,which is consistent with its higher covalent character compared to other species.As expected,the infrared and Raman spectra of[An@B₃₉]ⁿ⁺are similar to the C₂B₃₉^-cages.These actinide endohedral chiral borospherenes predicted in this work not only adds new members to the boron cluster family,but also provides a theoretical basis for design of chiral metalloborospherenes.2.Actinium metal（uranium,neptunium and curium）doped with boron cageThe mechanism of the doping of C₃B₃₉^-boron cage with uranium metal,neptunium metal and curium metal was studied,and the covalent bond characteristics of[An@B₃₉]ⁿ⁺（An=U,Np;n=3;An=Cm;n=2）were analyzed.Theoretical calculations show that U-,Np-and Cm-B₃₉boron clusters([U@B₃₉]³⁺,[Np@B₃₉]³⁺and[Cm@B₃₉]²⁺)have strong covalent bond properties,and according to borospherenes B^-₃₉,each boron cluster considers different multiplicity isomers.Theoretical calculations show that[U@B₃₉]³⁺has C₃symmetry,and the global minimum structure of[Np@B₃₉]³⁺and[Cm@B₃₉]²⁺has no symmetry（C₁）.All actinide metal-doped borospherenes[An@B₃₉]ⁿ⁺（An=U,Np;n=3;An=Cm;n=2）are endohedral structures and have a higher gap value（the difference between the occupied orbital and the lowest empty orbital）,especially C₃[U@B₃₉]³⁺.Bonding analysis shows that each complex in[U@B₃₉]³⁺,[Np@B₃₉]³⁺and[Cm@B₃₉]²⁺has the characteristics ofσ+πdouble delocalization,and Compared with Np-B bond and Cm-B bond,the U-B bond has High covalent bond.So,C₃[U@B₃₉]³⁺has higher covalent bond characteristics.Therefore,the covalent nature of the An-B bond may be essential for the formation of these metal-doped borospherenes.