Synthesis and Structural Characterization of Endohedral Pyrrolidinodimetallofullerene:La_2@C_(80)(CH_2)_2NTrt

摘要

Endohedral metallofullerenes present unique structures and properties because the encapsulated metal atom(s) can donate electrons to the fullerene cages.La_2@C_(80) has attracted special attention because of the three-dimensional random motion of two La atoms inside the C_(80) cage.To investigate whether the motion of metal atoms encapsulated inside fullerenes is controlled by exohedral addition,density functional calculations were carried out for the La_2@C_(80) derivatives.It is shown that the three-dimensional random motion of two La atoms in La_2@C_(80) can be restricted to the circular motion in a plane by attaching a silicon substituent on the outer surface of the C_(80) cage.Very recently,we have reported the preparation and characterization of the bis-silylated Ce_2@C_(80),in which the motion of two Ce atoms is regulated under a hexagonal ring on the equator by the electron donation from the silyl group to the C_(80) cage.Meanwhile,theoretical calculations predicted that the motion of two La atoms is not regulated in a Diels-Alder cycloadduct,La_2@C_(80)(C_8H_6(OCH_3)_2),in which the addend connects to the C-C bond junction between pentagonal and hexagonal rings (named 5,6-adduct).6 As may be apparent from the structural and electronic similarities between La_2@C_(80) and La_2@C_(80)(C_8H_6-(OCH_3)_2),the attachment of the C_8H_6(OCH_3)_2 group has no significant effect on the internal rotation of two La atoms.Such dynamic behaviors of metal atoms encapsulated in various func-tionalized endohedral fullerenes are of great interest in the field of nanomaterial science.