title: M2@C79N (M = Y, Tb): isolation and characterization of stable endohedral metallofullerenes exhibiting M-M bonding interactions inside aza[80]fullerene cages.
abstract: Y2@C79N and Tb2@C79N have been prepared by conducting the Kratschmer-Huffman electric-arc process under 20 Torr of N2 and 280 Torr of He with metal oxide-doped graphite rods. These new heterofullerenes were separated from the resulting mixture of empty cage fullerenes and endohedral fullerenes by chemical separation and a two-stage chromatographic process. Crystallographic data for Tb2@C79N x Ni(OEP) x 2 C6H6 demonstrate the presence of an 80-atom cage with idealized I(h) symmetry and two, widely separated Tb atoms inside with a Tb-Tb separation of 3.9020(10) A for the major terbium sites. The EPR spectrum of the odd-electron Y2@C79N indicates that the spin density largely resides on the two equivalent yttrium ions. Computational studies on Y2@C79N suggest that the nitrogen atom resides at a 665 ring junction in the equator on the fullerene cage and that the unpaired electron is localized in a bonding orbital between the two yttrium ions of this stable radical. Thus, the Tb-Tb bond length of the single-electron bond is an exceedingly long metal-metal bond.
authors.affiliation: Department of Chemistry, Virginia Polytechnic Institute and State University, Blacksburg, Virginia 24061, USA.
authors.forename: Tianming
authors.initials: T
authors.lastname: Zuo
authors.forename: Liaosa
authors.initials: L
authors.lastname: Xu
authors.forename: Christine M
authors.initials: CM
authors.lastname: Beavers
authors.forename: Marilyn M
authors.initials: MM
authors.lastname: Olmstead
authors.forename: Wujun
authors.initials: W
authors.lastname: Fu
authors.forename: T Daniel
authors.initials: TD
authors.lastname: Crawford
authors.forename: Alan L
authors.initials: AL
authors.lastname: Balch
authors.forename: Harry C
authors.initials: HC
authors.lastname: Dorn
mesh_terms: D001372:Aza Compounds / Q000138:chemical synthesis* / Q000302:isolation & purification; D018360:Crystallography, X-Ray; D004578:Electron Spin Resonance Spectroscopy; D037741:Fullerenes / Q000737:chemistry* / Q000302:isolation & purification; D008956:Models, Chemical; D008958:Models, Molecular; D009942:Organometallic Compounds / Q000138:chemical synthesis* / Q000302:isolation & purification; D013725:Terbium / Q000737:chemistry*; D013816:Thermodynamics; D015019:Yttrium / Q000737:chemistry*
chemical_list: D001372:Aza Compounds; D037741:Fullerenes; D009942:Organometallic Compounds; D013725:Terbium; D015019:Yttrium
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