title: X-ray structures of Sc2C2@C2n (n = 40-42): in-depth understanding of the core-shell interplay in carbide cluster metallofullerenes.
abstract: X-ray analyses of the cocrystals of a series of carbide cluster metallofullerenes Sc(2)C(2)@C(2n) (n = 40-42) with cobalt(II) octaethylporphyrin present new insights into the molecular structures and cluster-cage interactions of these less-explored species. Along with the unambiguous identification of the cage structures for the three isomers of Sc(2)C(2)@C(2v)(5)-C(80), Sc(2)C(2)@C(3v)(8)-C(82), and Sc(2)C(2)@D(2d)(23)-C(84), a clear correlation between the cluster strain and cage size is observed in this series: Sc-Sc distances and dihedral angles of the bent cluster increase along with cage expansion, indicating that the bending strain within the cluster makes it pursue a planar structure to the greatest degree possible. However, the C-C distances within Sc(2)C(2) remain unchanged when the cage expands, perhaps because of the unusual bent structure of the cluster, preventing contact between the cage and the C(2) unit. Moreover, analyses revealed that larger cages provide more space for the cluster to rotate. The preferential formation of cluster endohedral metallofullerenes for scandium might be associated with its small ionic radius and the strong coordination ability as well.
authors.affiliation: Life Science Center of Tsukuba Advanced Research Alliance, University of Tsukuba, Tsukuba, Ibaraki 305-8577, Japan.
authors.forename: Hiroki
authors.initials: H
authors.lastname: Kurihara
authors.forename: Xing
authors.initials: X
authors.lastname: Lu
authors.forename: Yuko
authors.initials: Y
authors.lastname: Iiduka
authors.forename: Hidefumi
authors.initials: H
authors.lastname: Nikawa
authors.forename: Makoto
authors.initials: M
authors.lastname: Hachiya
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