title: Charge transfer complexes of fullerenes containing C₆₀˙⁻ and C₇₀˙⁻ radical anions with paramagnetic Co(II)(dppe)₂Cl⁺ cations (dppe: 1,2-bis(diphenylphosphino)ethane).
abstract: The reduction of Co(II)(dppe)Cl2 with sodium fluorenone ketyl produces a red solution containing the Co(I) species. The dissolution of C60 in the obtained solution followed by the precipitation of crystals with hexane yields a salt {Co(I)(dppe)2(+)}(C60˙(-))·2C6H4Cl2 and a novel complex {Co(dppe)2Cl}(C60) (). With C70, only the crystals of {Co(dppe)2Cl}(C70)·0.5C6H4Cl2 () are formed. Complex contains zig-zag fullerene chains whereas closely packed double chains are formed from fullerenes in . According to the optical spectra and magnetic data charge transfer occurs in both and with the formation of the Co(II)(dppe)2Cl(+) cations and the C60˙(-) or C70˙(-) radical anions. In spite of the close packing in crystals, C60˙(-) or C70˙(-) retain their monomeric form at least down to 100 K. The effective magnetic moments of and of 1.98 and 2.27μB at 300 K, respectively, do not attain the value of 2.45μB expected for the system with two non-interacting S = 1/2 spins at full charge transfer to fullerenes. Most probably diamagnetic {Co(I)(dppe)2Cl}(0) and neutral fullerenes are partially preserved in the samples which can explain the weak magnetic coupling of spins and the absence of fullerene dimerization in both complexes. The EPR spectra of and show asymmetric signals approximated by several lines with g-factors ranging from 2.0009 to 2.3325. These signals originate from the exchange interaction between the paramagnetic Co(II)(dppe)2Cl(+) cations and the fullerene˙(-) radical anions.
authors.affiliation: Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia. konarev3@yandex.ru.
authors.forename: Dmitri V
authors.initials: DV
authors.lastname: Konarev
authors.affiliation: Chemistry Department, Moscow State University, Leninskie Gory, 119991 Moscow, Russia.
authors.forename: Sergey I
authors.initials: SI
authors.lastname: Troyanov
authors.affiliation: Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Akihiro
authors.initials: A
authors.lastname: Otsuka
authors.affiliation: Research Center for Low Temperature and Materials Sciences, Kyoto University, Sakyo-ku, Kyoto 606-8501, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yamochi
authors.affiliation: Faculty of Agriculture, Meijo University, 1-501 Shiogamaguchi, Tempaku-ku, Nagoya 468-8502, Japan and Toyota Physical and Chemical Research Institute, 41-1, Yokomichi, Nagakute, Aichi 480-1192, Japan.
authors.forename: Gunzi
authors.initials: G
authors.lastname: Saito
authors.affiliation: Institute of Problems of Chemical Physics RAS, Chernogolovka, Moscow region, 142432 Russia. konarev3@yandex.ru.
authors.forename: Rimma N
authors.initials: RN
authors.lastname: Lyubovskaya