title: Crystallographic Evidence for Direct Metal-Metal Bonding in a Stable Open-Shell La2 @Ih -C80 Derivative.
abstract: Endohedral metallofullerenes (EMFs) have novel structures and properties that are closely associated with the internal metallic species. Benzyl radical additions have been previously shown to form closed-shell adducts by attaching an odd number of addends to open-shell EMFs (such as Sc3 C2 @Ih -C80 ) whereas an even number of groups are added to closed-shell EMFs (for example Sc3 N@Ih -C80 ). Herein we report that benzyl radical addition to the closed-shell La2 @Ih -C80 forms a stable, open-shell monoadduct instead of the anticipated closed-shell bisadduct. Single-crystal X-ray diffraction results show the formation of a stable radical species. In this species, the La-La distance is comparable to the theoretical value of a La-La covalent bond and is shorter than reported values for other La2 @Ih -C80 derivatives, providing unambiguous evidence for the formation of direct La-La bond.
authors.affiliation: State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037, Luoyu Road, Wuhan, 430074, P.R. China.
authors.forename: Lipiao
authors.initials: L
authors.lastname: Bao
authors.affiliation: State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037, Luoyu Road, Wuhan, 430074, P.R. China.
authors.forename: Muqing
authors.initials: M
authors.lastname: Chen
authors.affiliation: State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037, Luoyu Road, Wuhan, 430074, P.R. China.
authors.forename: Changwang
authors.initials: C
authors.lastname: Pan
authors.affiliation: Graduate School of Human and Environmental Sciences, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Takahisa
authors.initials: T
authors.lastname: Yamaguchi
authors.affiliation: Graduate School of Human and Environmental Sciences, Kyoto University, Kyoto, 606-8501, Japan.|Institute for Liberal Arts and Sciences, Kyoto University, Kyoto, 606-8501, Japan.
authors.forename: Tatsuhisa
authors.initials: T
authors.lastname: Kato
authors.affiliation: Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA.
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.affiliation: Department of Chemistry, University of California, Davis, Davis, CA, 95616, USA.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Balch
authors.affiliation: State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037, Luoyu Road, Wuhan, 430074, P.R. China.|Foundation for Advancement of International Science, Tsukuba, 30-0821, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Akasaka
authors.affiliation: State Key Laboratory of Materials Processing and Die and Mold Technology, School of Materials Science and Engineering, Huazhong University of Science and Technology, 1037, Luoyu Road, Wuhan, 430074, P.R. China. lux@hust.edu.cn.
authors.forename: Xing
authors.initials: X
authors.lastname: Lu
keywords: density functional calculations; endohedral fullerenes; metal-metal bonding; radical reactions; structure elucidation