Effective derivatization and extraction of insoluble missing lanthanum metallofullerenes La@C2n (n = 36-38) with iodobenzene

Extraction of insoluble metallofullerenes, La@C2n (n = 36-38), was conducted with dichlorobenzene, chlorobenzene, and iodobenzene as a solvent under reflux condition. When iodobenzene was used, La@C2n (n = 36-38) was successfully extracted as the corresponding phenyl adducts, such as La@C72(C6H5), La@C74(C6H5), and La@C76(C6H5). The number of isomers of corresponding adducts, La@C72(C6H5) and La@C74(C6H5), were reduced to one-third of that in 1,2,4-trichlorobenzene extracts, which was reported previously. Based on the spectroscopic analysis, the carbon cages of La@C72(C6H5) and La@C74(C6H5) were deduced to be La@C2(10612)-C72(C6H5) and La@D3h-C74(C6H5), respectively. The addition site carbon possessing very high radical character suggests that the corresponding adducts were produced by the addition of phenyl radical generated from iodobenzene on metallofullerenes.