title: Formation of single-bonded (C60-)2 and (C70-)2 dimers in crystalline ionic complexes of fullerenes.
abstract: New ionic complexes of fullerenes C(60) and C(70) with decamethylchromocene Cp*(2)Cr.C60.(C(6)H(4)Cl(2))(2) (1), Cp*(2)Cr.C60.(C(6)H(6))(2) (2); the multicomponent complex of (Cs(+))(C70-) with cyclotriveratrylene CTV.(Cs)(2).(C70)(2).(DMF)(7).(C(6)H(6))(0.75) (3); bis(benzene)chromium Cr(C(6)H(6))(2).C60.(C(6)H(4)Cl(2))(0.7) (4), Cr(C(6)H(6))(2).C60.C(6)H(5)CN (5), Cr(C(6)H(6))(2).C70.C(6)H(4)Cl(2) (6), Cr(C(6)H(6))(2).C60 (7); cobaltocene Cp(2)Co.C60.C(6)H(4)Cl(2) (8), Cp(2)Co.C70.(C(6)H(4)Cl(2))(0.5) (9); and cesium Cs.C70.(DMF)(5) (10) have been obtained. The complexes have been characterized by the elemental analysis, IR-, UV-vis-NIR spectroscopy, EPR and SQUID measurements. It is shown that C(60)(.-) exists as a single-bonded diamagnetic (C60-)2 dimer in 1, 2, 4, 5, and 8 at low temperatures (1.9-250 K). The dimers dissociate above 160-250 K depending on donor and solvent molecules involved in the complex. C60(.-) dimerizes reversibly and shows a small hysteresis (<2 K) at slow cooling and heating rates. The single-bonded diamagnetic (C70-)2 dimers are also formed in 6, 9, and 10 and begin to dissociate only above 250-360 K. The IR and UV-vis-NIR spectra of sigma-bonded negatively charged fullerenes are presented.
authors.affiliation: Division of Chemistry, Graduate School of Science, Kyoto University, Sakyo-ku, Kyoto 606-8502, Japan. konarev@icp.ac.ru
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Konarev
authors.forename: Salavat S
authors.initials: SS
authors.lastname: Khasanov
authors.forename: Gunzi
authors.initials: G
authors.lastname: Saito
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otsuka
authors.forename: Yukihiro
authors.initials: Y
authors.lastname: Yoshida
authors.forename: Rimma N
authors.initials: RN
authors.lastname: Lyubovskaya