title: Where does the metal cation stay in Gd@C2v(9)-C82? A single-crystal X-ray diffraction study.
abstract: Metal positions in endohedral metallofullerenes (EMFs) are of special importance because their molecular symmetry and intrinsic properties are strongly influenced by the location and motion of the encapsulated metals. X-ray analyses of the cocrystals of Gd@C(2v)(9)-C(82) with nickel(II) octaethylporphyrin [Ni(II)(OEP)] reveal that the Gd(3+) cation is off-center, being located under a hexagonal ring along the 2-fold axis of the C(2v)(9)-C(82) cage. This result is in sharp contrast to that of a previous study, showing that Gd@C(2v)(9)-C(82) has an anomalous endohedral structure, with the metal being positioned over a [6,6] bond, which is opposite to the hexagonal ring along the C(2) axis (Phys. Rev. B 2004, 69, 113412). In agreement with theoretical calculations and related studies, it is conclusive that the single rare-earth metal in M@C(2v)(9)-C(82) always tends to coordinate with the hexagonal ring along the 2-fold axis, instead of interacting with the [6,6] bond on the other end, regardless of the type of metal atom.
authors.affiliation: Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Mitsuaki
authors.initials: M
authors.lastname: Suzuki
authors.forename: Xing
authors.initials: X
authors.lastname: Lu
authors.forename: Satoru
authors.initials: S
authors.lastname: Sato
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Nikawa
authors.forename: Naomi
authors.initials: N
authors.lastname: Mizorogi
authors.forename: Zdenek
authors.initials: Z
authors.lastname: Slanina
authors.forename: Takahiro
authors.initials: T
authors.lastname: Tsuchiya
authors.forename: Shigeru
authors.initials: S
authors.lastname: Nagase
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akasaka