Synthesis of a Hydrocarbon Salt Having a Fullerene Framework

Tanaka, Toru; Kitagawa, Toshikazu; Komatsu, Kôichi; Takeuchi, Ken′ichi

doi:10.1021/ja970006x

Cited by 19 publications

(12 citation statements)

References 20 publications

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“…Figure shows the vis−NIR spectral changes observed in the reaction of C 60 2- with t -BuI in PhCN. As the reaction proceeds, the C 60 2- absorption band at λ max = 955 nm decreases, and this is accompanied by the appearance of a new absorption band at 660 nm, which is a diagnostic marker band of monoalkyl C 60 adduct anions . The same spectral changes were observed in the reactions of C 60 2- with each alkyl halide (RX) to yield RC 60 - and the stoichiometry of the reaction is given by eq 1 for the case of RX = t- BuI.…”

Section: Resultsmentioning

confidence: 77%

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

et al. 1998

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The formation of organofullerenes of the type R2C60 and R(R‘)C60 from C60 2- and alkyl halides (RX or R‘X) in benzonitrile was mechanistically investigated for 15 different alkyl halides which vary in electrophilicity and electron acceptor ability. The first step in the reaction leads to RC60 - via an electron-transfer mechanism, followed by formation of R2C60 or R(R‘)C60 via an SN2 mechanism. Evidence of the mechanism comes from comparison of rate constants for the stepwise addition of two R groups to C60 2- with rate constants for the genuine electron transfer and SN2 reactions. The formation of t-BuC60 - and PhCH2C60 - after the first R group addition was confirmed by electrospray ionization mass spectroscopy. The t-BuC60 - derivative will not react further with excess t-BuI, but this is not the case for the less sterically hindered PhCH2Br, which adds to t-BuC60 - in benzonitrile to give t-Bu(PhCH2)C60. A protonation of t-BuC60 - with trifluoroacetic acid can also occur to give 1,4-t-Bu(H)C60, which rearranges rapidly to yield 1,2-t-Bu(H)C60. Rate constants for the second alkylation of t-BuC60 - with a variety of different alkyl halides are compared with values of genuine SN2 reactions and indicate that the second step in the fullerene alkylation reaction proceeds via an SN2 mechanism. The rate constants of electron transfer from C60 2- to RX span a range of 105, but are insensitive to the steric effect of the alkyl group, i.e., they depend only on the electron-acceptor ability of RX. In contrast, the SN2 rate constants of t-BuC60 - with RX are highly susceptible to the steric effect of the alkyl group and no reaction at all takes place between t-BuC60 - and t-BuI. Thus, the first addition of one sterically hindered alkyl group to C60 2- occurs via electron transfer and cannot be followed by further addition of a second sterically hindered group (via an SN2 reaction). This is not the case for less sterically hindered alkyl groups such as benzyl bromide which can add via an SN2 reaction to yield C60 adducts with two different alkyl groups.

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Section: Resultsmentioning

confidence: 77%

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

et al. 1998

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“…Also in support of the intermediacy of the fullerenyl anion for the reaction of C 60 by the action of carbon nucleophiles, the dimerization was observed upon HSVM treatment of C 60 (40 mg) with a catalytic amount (1.4 or 1.5 mg; 3 mol % relative to C 60 ) of the potassium salt of the fullerenyl anion, t -BuC 60 - or C 60 (CN) - , in the presence of 100 mg of KCl as an solid diluent. After 30 min, an equilibrium mixture of C 60 and C 120 (67.5:31.2 or 93.4:5.9 by HPLC for the reaction of t -BuC 60 - or C 60 (CN) - , respectively) was obtained, while no ODCB-insoluble material was produced.…”

Section: Resultsmentioning

confidence: 81%

Mechanochemical Synthesis and Characterization of the Fullerene Dimer C₁₂₀

Komatsu¹,

Wang²,

Murata³

et al. 1998

J. Org. Chem.

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229

242

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The bulk synthesis of the [2 + 2] dimer of fullerene C 60 was achieved by the solid-state mechanochemical reaction of C 60 with KCN by the use of a high-speed vibration milling (HSVM) technique. This reaction took place also by the use of potassium salts such as K 2 CO 3 and CH 3 -CO 2 K, metals such as Li, Na, K, Mg, Al, and Zn, and organic bases such as 4-(dimethylamino)-and 4-aminopyridine. Under optimum conditions, the reaction afforded only the dimer C 120 and unchanged C 60 in a ratio of about 3:7 (by weight) regardless of the reagent used. The dimer C 120 was fully characterized by IR, UV-vis, 13 C NMR, and TOF MS spectroscopies, cyclic voltammetry, and differential scanning calorimetry. Comparison of the IR and 13 C NMR spectral data of C 120 with those reported for all-carbon C 60 polymers implied that the [2 + 2] dimer C 120 represents the essential subunit of these polymers. The dimer C 120 underwent facile dissociation into two C 60 molecules by heat, HSVM treatment, exposure to room light, or electrochemical reduction. The dimer C 120 encapsulating 3 He in one of the C 60 cages was synthesized and was used to confirm the scrambling of a C 60 cage between the monomer and the dimer during the HSVM reaction. A possible mechanism for the selective formation of the dimer C 120 is proposed.

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“…For instance, it enters into the Bingel reaction with diethyl bromomalonate and DBU (in equimolar amounts) to give a mixture of isomeric monoadducts (at least, three compounds) in 44% total yield. 118 Tanaka et al 119 made use of the fact that the fullerene spheroid readily forms anions and synthesised an unusual class of compounds, hydrocarbon salts.…”

Section: C60 + H2nr C60mentioning

confidence: 99%

Fullerenes: functionalisation and prospects for the use of derivatives

Karaulova¹,

Bagrii²

1999

Russ. Chem. Rev.

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Synthesis of a Hydrocarbon Salt Having a Fullerene Framework

Cited by 19 publications

References 20 publications

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

Mechanochemical Synthesis and Characterization of the Fullerene Dimer C₁₂₀

Fullerenes: functionalisation and prospects for the use of derivatives

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Synthesis of a Hydrocarbon Salt Having a Fullerene Framework

Cited by 19 publications

References 20 publications

Formation of C60Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and SN2 Reactions

Formation of C60Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and SN2 Reactions

Mechanochemical Synthesis and Characterization of the Fullerene Dimer C120

Fullerenes: functionalisation and prospects for the use of derivatives

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Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

Formation of C₆₀Adducts with Two Different Alkyl Groups via Combination of Electron Transfer and S_N2 Reactions

Mechanochemical Synthesis and Characterization of the Fullerene Dimer C₁₂₀