Addition of Amines
Owing to their high nucleophilicity, primary and secondary aliphatic amines undergo nucleophilic additions with the electron-deficient C60 2, 76-82 . Treating solid C60 in neat amines, for example in propylamine or ethylenediamine, leads to the formation of green solutions fast process that eventually turn chestnut brown slow process 2 . The green color of the intermediates is typical for anion complexes of C60 5, 83 . Careful monitoring of these reactions with ESR and UV Vis NIR spectroscopy...
Addition of Hydroxide and Alkoxides
Heating of C60 C70 mixtures in toluene in the presence of an excess of KOH leads to the formation of a precipitate of hydroxylated fullerenes fullerenols , which are soluble in THF but decompose due to the presence of air 107 . The addition of hydroxide to C70 proceeds significantly faster than to C60. This was concluded from time-dependent measurements with UV Vis spectroscopy, as well as by the observation that during the reaction the red C60 C70 mixture turns to purple before all the...
Synthesis and Properties of Alkali Metal Fulleride Solids
The discovery of superconductivity 105 in alkali metal doped C60 attracted the attention of a broad cross-section of the scientific community. The composition of the first alkali metal doped fullerene was determined to be K3C60 106, 107 . In this compound, the transition to a superconducting state occurs at Tc 19.3 K 106 . In a short time, a large variety of alkali metal fullerides MnC60 have been synthesized and studied with respect to their solid-state properties 1, 106-114 . Thereby, the...
Oxygenation
Oxygenated fullerenes C60On and C70On can be found in the fullerene mixture generated by graphite vaporization 11, 12 . The formation of these oxides is due to a small amount of molecular oxygen present in the fullerene reactor. C70O was isolated from the fullerene extract by preparative HPLC 11 . Mixtures of C60On n up to 4 can also be generated by electrochemical oxidation of C60 13 or by photolysis of the crude fullerene extract 12 . More drastic conditions, such as UV irradiation in hexane...
References 1
1 F. Wudl, A. Hirsch, K. C. Khemani, T. Suzuki, P. M. Allemand, A. Koch, H. Eckert, G. Srdanov, H. M. Webb, ACS Symp. Ser. 1992, 481,161. 2 M. A. Yurovskaya, I. V. Trushkov, Russ. Chem. Bull. 2002, 51, 367. 3 S. R. Wilson, D. I. Schuster, B. Nuber, M. S. Meier, M. Maggini, M. Prato, R. Taylor, Full. Chem., Phys. Technol. 2000, 91. 4 B. Kr utler, J. Maynollo, Tetrahedron 1996, 52, 5033. 5 S. R. Wilson, Q. Lu, Tetrahedron Lett. 1993, 34, 8043. 6 F. Langa, P. de la Cruz, E. Espildora, J. J....
Reduction with Organic Donor Molecules
The synthesis and isolation of fulleride salts is also possible with organic or metal organic donor molecules. Since a large variety of molecular compounds fulfill the requirement of being a donor of sufficient strength, it can be expected to gain access to materials with tunable solid-state properties. The first examples offullerene based charge-transfer CT complexes, containing molecular cationic species already showed a remarkable electronic and magnetic behavior 102, 143-149 . The...
Alkaline Earth Metal Fullerides
Alkaline earth metals can also be intercalated with C60 1, 112-114, 130-137 . The preparation of Ca5C60 131 , Ba6C60 133, 138 , BaxC60 with 3-6 134 or Ba4C60 and Sr4C60 135 has been achieved by the direct reaction of C60 with the corresponding alkaline earth metal vapor. Therefore, the alkaline earth-metal is mixed with C60 in an inert atmosphere and the powder is then placed into a custom designed high-purity tantalum cell, which allows compression into pellets. The pellets are then loaded...
E Volts vs Ferrocene
Figure 8.1 CV for C60 and C70 in 0.1 M TBA PF6 TCE at room temperature CVs were run at a scan rate of 100 mV s-1. CV with C60 A and C70 B , no ferrocene added. Cathodic and anodic cyclic scans were performed separately 7 . energy difference between the HOMO and the LUMO in solution and was determined to be 2.32 V for C60 and 2.22 V for C70. The cationic radical species generated electrochemically are relatively long-lived at room temperature. The lifetime of the radicals was estimated to be gt...
Total Synthesis Approaches
Fullerene generation by vaporization of graphite or by combustion of hydrocarbons is very effective and certainly unbeatable what facile production in large quantities is concerned. However, total synthesis approaches are attractive because a specific fullerenes could be made selectively and exclusively, b new endohedral fullerenes could be formed, c heterofullerenes and d other cluster modified fullerenes could be generated using related synthesis protocols. Scheme 1.4 Conversion of cyclophane...
Direct Fluorination with F
Allowing fluorine gas at low pressure to react with the solid fullerene Scheme 9.1 11, 15, 16 was among the first halogenation reactions performed with C60. After the first promising results, direct fluorination 7, 8, 17 was carried out under various conditions 18-23 . Different pressures and temperatures were applied, the reaction was carried out under static conditions or with a stream of fluorine and different reaction vessels such as quartz, steel or Monel were used. Monel is a...
Hydrognation via Hydroboration and Hydrozirconation
One approach to the synthesis of hydrofullerenes is the defined stoichiometrically controlled addition to one or a few reactive 6,6 double bonds of C60 and C70. Presuming that the addition patterns are similar to those of nucleophilic additions and cycloadditions see Chapters 3 and 4 , a limited number ofenergetically favored isomers can be expected in the reaction mixtures. This would allow the chromatographic isolation and also the systematic characterization of isomerically pure...
Electrocrystallization
The possibility of electrochemically producing C60 anions in a defined oxidation state by applying a proper potential can be used to synthesize fulleride salts by electrocrystallization 39, 75-80 . An obvious requirement for this purpose is the insolubility of the salt in the solvent to be used for the electrocrystallization process. This can be achieved by choosing the proper solvent, the oxidation state of C60 and the counter cation, which usually comes from the supporting electrolyte....