title: Regioselective cage opening of La2 @D2 (10611)-C72 with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine.
abstract: The thermal reaction of the endohedral metallofullerene La2 @D2 (10611)-C72 , which contains two pentalene units at opposite ends of the cage, with 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine proceeded selectively to afford only two bisfulleroid isomers. The molecular structure of one isomer was determined using single-crystal X-ray crystallography. The results suggest that the [4+2] cycloaddition was initiated in a highly regioselective manner at the C-C bond connecting two pentagon rings of C72 . Subsequent intramolecular electrocyclization followed by cycloreversion resulted in the formation of an open-cage derivative having three seven-membered ring orifices on the cage and a significantly elongated cage geometry. The reduction potentials of the open-cage derivatives were similar to those of La2 @D2 -C72 whereas the oxidation potentials were shifted more negative than those of La2 @D2 -C72 . These results point out that further oxidation could occur easily in the derivatives.
authors.affiliation: Department of Chemistry, Tokyo Gakugei University, Koganei, Tokyo 184-8501 (Japan).
authors.forename: Michio
authors.initials: M
authors.lastname: Yamada
authors.forename: Yasuhiro
authors.initials: Y
authors.lastname: Muto
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurihara
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Slanina
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Maeda
authors.forename: Yves
authors.initials: Y
authors.lastname: Rubin
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Alan L
authors.initials: AL
authors.lastname: Balch
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase
authors.forename: Xing
authors.initials: X
authors.lastname: Lu
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akasaka
keywords: X-ray diffraction; cycloadditions; electrochemistry; fullerenes; lanthanum