title: Synthesis and Isolation of the Titanium-Scandium Endohedral Fullerenes-Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 and Sc2 TiC2 @Ih -C80 : Metal Size Tuning of the Ti(IV) /Ti(III) Redox Potentials.
abstract: The formation of endohedral metallofullerenes (EMFs) in an electric arc is reported for the mixed-metal Sc-Ti system utilizing methane as a reactive gas. Comparison of these results with those from the Sc/CH4 and Ti/CH4 systems as well as syntheses without methane revealed a strong mutual influence of all key components on the product distribution. Whereas a methane atmosphere alone suppresses the formation of empty cage fullerenes, the Ti/CH4 system forms mainly empty cage fullerenes. In contrast, the main fullerene products in the Sc/CH4 system are Sc4 C2 @C80 (the most abundant EMF from this synthesis), Sc3 C2 @C80 , isomers of Sc2 C2 @C82 , and the family Sc2 C2 n (2 n=74, 76, 82, 86, 90, etc.), as well as Sc3 CH@C80 . The Sc-Ti/CH4 system produces the mixed-metal Sc2 TiC@C2 n (2 n=68, 78, 80) and Sc2 TiC2 @C2 n (2 n=80) clusterfullerene families. The molecular structures of the new, transition-metal-containing endohedral fullerenes, Sc2 TiC@Ih -C80 , Sc2 TiC@D5h -C80 , and Sc2 TiC2 @Ih -C80 , were characterized by NMR spectroscopy. The structure of Sc2 TiC@Ih -C80 was also determined by single-crystal X-ray diffraction, which demonstrated the presence of a short Ti=C double bond. Both Sc2 TiC- and Sc2 TiC2 -containing clusterfullerenes have Ti-localized LUMOs. Encapsulation of the redox-active Ti ion inside the fullerene cage enables analysis of the cluster-cage strain in the endohedral fullerenes through electrochemical measurements.
authors.affiliation: Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069, Dresden, Germany.
authors.forename: Katrin
authors.initials: K
authors.lastname: Junghans
authors.affiliation: Department of Chemistry, University of California, Davis, 95616, USA.
authors.forename: Kamran B
authors.initials: KB
authors.lastname: Ghiassi
authors.affiliation: Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069, Dresden, Germany.
authors.forename: Nataliya A
authors.initials: NA
authors.lastname: Samoylova
authors.affiliation: Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069, Dresden, Germany.
authors.forename: Qingming
authors.initials: Q
authors.lastname: Deng
authors.affiliation: Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069, Dresden, Germany.
authors.forename: Marco
authors.initials: M
authors.lastname: Rosenkranz
authors.affiliation: Department of Chemistry, University of California, Davis, 95616, USA. mmolmstead@ucdavis.edu.
authors.forename: Marilyn M
authors.identifier: http://orcid.org/0000-0002-6160-1622
authors.initials: MM
authors.lastname: Olmstead
authors.affiliation: Department of Chemistry, University of California, Davis, 95616, USA. albalch@ucdavis.edu.
authors.forename: Alan L
authors.initials: AL
authors.lastname: Balch
authors.affiliation: Leibniz Institute for Solid State and Materials Research (IFW Dresden), Helmholtzstraße 20, 01069, Dresden, Germany. a.popov@ifw-dresden.de.
authors.forename: Alexey A
authors.identifier: http://orcid.org/0000-0002-7596-0378
authors.initials: AA
authors.lastname: Popov
keywords: fullerenes; methane; mixed-metal compounds; scandium; titanium