Controlled two-step nucleophilic hydroalkylations, hydroarformed. In all cases the addition takes place at a double bond ylations as well as hydrostannylations of fullerene-60 (1) and separating two six-membered rings of the fullerene core. In fullerene-70 (2) lead to defined organodihydrofullerenes this way a variety of organodihydrofullerenes also carrying CWHR and C,,HR. NMR investigations show that only one functional groups have been synthesized. isomer of each organodihydrofullerene with C, symmetry isThe spherical all-carbon Ih molecule fullerene-60 (C,) consists of 12 isolated pentagons and 20 hexagons. Structural data"] and calculations [*] demonstrate that the bonds between two hexagons (6 -6 bonds) exhibit double-bond character. The bonds between the pentagons and hexagons (5 -6 bonds) with single-bond character are significantly longer, also showing a much lower electron density. Therefore, fullerene-60 can be considered a sphere built up of fused [Slradialene and cyclohexatriene units. This structural argument is supported by its chemical reactivity. One-step additions to c60, namely the addition of osmium tetroxide ['], transition-metal complexes[41 or 1,3-dipolesr5I, exclusively take place at the 6-6 bonds. The other important chemical property of Cs0 (1) is its high electrophilicityt6I and affinity towards radicals[71. Due to the polyfunctionality (thirty 6 -6 bonds), an uncontrolled reaction leads to a huge number of different addition products which are impossible to isolate. Only few examples for the preparation of isomerically pure single compounds are k n~w n [ ' -~, * -~'~ . R ecentlyP1, we have shown that it is possible to control even two-step nucleophilic additions to a 6 -6 bond and to isolate the isomerically pure organodihydrofullerenes 1-tert-butyl-and l-ethyl-l,9-dihydrofullerene-60"*l (5b and 5c). Thereby 1 was titrated with tert-butyllithium or ethylmagnesium bromide and subsequently protonated under HPLC control. This method opens up the access to a variety of functionalized organodihydrofullerenes which for example can serve as precursors for further reactions. Independently, 5b was In this paper we show that the titration method ['] can generally be used for the hydroalkylation and hydroarylation of fullerene-60. Also the addition of radicals can be controlled quantitatively by HPLC. In this way we prepared a variety of isomerically pure 1,9-adducts of 1 and determined their spectroscopic properties. For the first time we performed the additions of nucleophiles to fullerene-70 (2) by using our titration method and showed that also in this case single regioisomers with C, symmetry are formed. Results and Discussion Synthesis of Organodihydrofullerenes 5 -8Cs0 (1) and C70 (2) were treated with various nucleophiles in benzene because besides carbon disulfide mainly aromatic solvents guarantee a sufficient solubility. The nucleophile addition, carried out stepwise, leads to a dark brown precipitate of the fullerides 3, 4 and C70R-, which upon rapid stirring is suspended homogeneou...
Isomerically pure monoadducts of C60 such as C60HEt (only the front aspect shown on the right) were obtained from the titration of C60 with alkyllithium or Grignard reagents, followed by protonation. The nucleophile adds to the fullerene framework at a double bond between two six‐rings, as was confirmed by the results of AMI calculations. This method may provide access to organofullerenes C60RR′ and C60R2.
Metall-Metall-Bindung zu oxidieren, konnte erklaren, warum dieses Ion bei derartigen Oxidationen so wirksam ist. Die bei der Kniipfung der starken Metall-Metall-Bindung und bei der raumlichen Umverteilung in den Koordintionsspharen von 0 s und Ag freiwerdende Energie reicht offenbar aus, um den Elektronentransfer und damit die Isolierung von 2 zu ermoglichen. Die Bildung von Silberkeimen kann ebenfalls eine Rolle spielen. Wir haben eine Induktionsperiode (die einem Geschwindigkeitsgesetz nullter Ordnung gehorcht) beim weiteren Elektronentransfer von 2 in Dichlormethan beobachtet, die anscheinend mit der Bildung von Silbermetall einhergeht. Das gemessene Redoxpotential von Agf bezieht sich auf seine Reduktion zu Silbermetall. Eine Elektronentransfer-Reaktion wiirde aus 2 demnach zunachst ein solvatisiertes Ag-Atom freisetzen, das ein Intermediat mit hoherem Energieinhalt sein konnte. ExperimentellesAlle Experimente wurden unter N, in wasserfreien Losungsmitteln durchgefuhrt. 1 wurde nach der Methode von Collman und Roper [6] hergestellt. 2: Unter LichtausschluB wurden zu einer Mischung aus 1 (40 mg, 0.050 mmol) und Ag(O,CCF,) (1 1 mg, 0.050 mmol) 10 mL THF gegehen und die entstandeue Mischung 10 min geruhrt. Das Losungsmittel wurde anschlieBend im Vakuum entfernt uud der hellbraune Ruckstand rnit 15 mL Benzol extrahiert. Nach Filtration wurde die Benzol-Losung auf ca. 5 mL eingeengt und 30 mL Pentan hinzugefiigt. Dabei fielen 14 mg 2 (27% Ausb.) aus. Fur eine Rontgenstrukturanalyse geeignete Kristalle von 2 . 0.5 C,H, erhielt man nach mehrtagiger Lagerung der Benzol/Pentan-Losung bei 5 "C. Eiugegangen am 15. November 1991 [Z 50201 R. A. Marcus, Annu. Rev. Phys. Dalton Trans. 1991, 2253. Kristallstrukturanalyse von 2 . 0.5 C,H,: Monoklin, P2,/n, a = 11.042(2), b =13.431(3), c = 27.709(5) A, p =101.05(1)", Y = 4033.2(14) A', 2 = 4, ebex =1.744 gcm-', p = 3.767 mm-', Mo,,-Strahlung, Graphit-Monochromator, 7134 unabhangige Reflexe, davon 4332 mit Fo t 6 . 0~ (FJ, 3" s 2 8 I 5 5 " , Empirische Absorptionskorrektur (Psi-Scan). Strukturverfeinerung rnit Direkten Methoden, R = 0.044, R, = 0.066. Weitere
Langmuir-Blodgett (LB) films of 1 -tert-butyl-l,9-dihydrofullerene-60 are shown to undergo well defined multistage electrochemical reductions to yield the trianion species, with the first two redox waves stable to recycling; these data contrast with those for LB films of the parent system C6*.
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