title: The Unanticipated Dimerization of Ce@C2v(9)-C82upon Co-crystallization with Ni(octaethylporphyrin) and Comparison with Monomeric M@C2v(9)-C82(M = La, Sc, and Y).
abstract: We report that Ce@C2v(9)-C82forms a centrosymmetric dimer when co-crystallized with Ni(OEP) (OEP = octaethylporphyrin dianion). The crystal structure of {Ce@C2v(9)-C82}2⋅2[Ni(OEP)]⋅4 C6H6shows that a new C-C bond with a bond length of 1.605(5) Å connects the two cages. The high spin density of the singly occupied molecular orbital (SOMO) on the cage and the pyramidalization of the cage are factors that favor dimerization. In contrast, the treatment of Ni(OEP) with M@C2v(9)-C82(M = La, Sc, and Y) results in crystallization of monomeric endohedral fullerenes. A systematic comparison of the X-ray structures of M@C2v(9)-C82(M = Sc, Y, La, Ce, Gd, Yb, and Sm) reveals that the major metal site in each case is located at an off-center position adjacent to a hexagonal ring along the C2axis of the C2v(9)-C82cage. DFT calculations at the M06-2X level revealed that the positions of the metal centers in these metallofullerenes M@C2v(9)-C82(M = Sc, Y, and Ce), as determined by single-crystal X-ray structure studies, correspond to an energy minimum for each compound.
authors: Department of Chemistry, Josai University, Saitama, 350-0295, Japan.|Department of Chemistry, Tokyo Gakugei University, Tokyo, 184-8501, Japan.
authors: Mitsuaki
authors: M
authors: Suzuki
authors: Department of Chemistry, Tokyo Gakugei University, Tokyo, 184-8501, Japan.
authors: Michio
authors: M
authors: Yamada
authors: Department of Chemistry, Tokyo Gakugei University, Tokyo, 184-8501, Japan.
authors: Yutaka
authors: Y
authors: Maeda
authors: Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaraki, 305-8588, Japan.
authors: Satoru
authors: S
authors: Sato
authors: Institute for Integrated Cell-Material Sciences (WPI-iCeMS), Kyoto University, Kyoto, 615-8510, Japan.
authors: Yuta
authors: Y
authors: Takano
authors: Department of Physical and Macromolecular Chemistry, Charles University in Prague, 128 43, Prague 2, Czech Republic.
authors: Filip
authors: F
authors: Uhlík
authors: Department of Chemistry and Biochemistry, National Chung-Cheng University, Chia-Yi, 62117, Taiwan R.O.C.
authors: Zdenek
authors: Z
authors: Slanina
authors: Key Laboratory of Functional Inorganic Material Chemistry, Ministry of Education, School of Chemistry and Materials Science, Heilongjiang University, Harbin, 150080, P.R. China.
authors: Yongfu
authors: Y
authors: Lian
authors: State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong, University of Science and Technology, Wuhan, 430074, P.R. China.
authors: Xing
authors: X
authors: Lu
authors: Fukui Institute for Fundamental Chemistry, Kyoto University, Kyoto, 606-8103, Japan.
authors: Shigeru
authors: S
authors: Nagase
authors: Department of Chemistry, University of California, Davis, California, 95616, USA.
authors: Marilyn M
authors: MM
authors: Olmstead
authors: Department of Chemistry, University of California, Davis, California, 95616, USA.
authors: Alan L
authors: AL
authors: Balch
authors: Department of Chemistry, Tokyo Gakugei University, Tokyo, 184-8501, Japan.|Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Ibaraki, 305-8588, Japan.|State Key Laboratory of Materials Processing and Die & Mold Technology, School of Materials Science and Engineering, Huazhong, University of Science and Technology, Wuhan, 430074, P.R. China.|Foundation for Advancement of International Science, Tsukuba, Ibaraki, 305-0821, Japan.
authors: Takeshi
authors: T
authors: Akasaka
keywords: cage compounds; crystal growth; dimerization; metallofullerenes; structure elucidation