Fullerene aromaticity

Castells, Some comments on fullerene terminology, nomenclature, and aromaticity, Fullerene Sci. Technol. 2, 367-379 (1994). 

The scope of aromaticity is thus much broader for Hiickel-type annulenes than for fullerenes, where it is essentially limited to delocalization evidenced by ring currents. The prediction that according to the computed NMR criteria C6o ° should the most aromatic fullerene derivative to date does not mean it will be easily, or ever, synthesized. Yet the classifica-... 

Bausch J W, Prakash G K S, Olah G A, Tse D S, Lorents D C, Bae Y K and Malhotra R 1991 Considered novel aromatic systems. 11. Diamagnetic polyanions of the Cgg and C g fullerenes. preparation, 13-C and 7-Li NMR spectroscopic observation, and alkylation with methyliodide to polymethylated fullerenes J. Am. 

Physical properties of Fullerene C q. It does not melt below 360°, and starts to sublime at 300° in vacuo. It is a mustard coloured solid that appears brown or black with increasing film thickness. It is soluble in common organic solvents, particularly aromatic hydrocarbons which give a beautiful magenta colour. Toluene solutions are purple in colour. Sol in (5mg/mL), but dissolves slowly. Crysts of C o are both needles and plates. 

Reduction of fullerenes to fullerides — Reversible electrochemical reduction of Ceo in anhydrous dimethylformamide/toluene mixtures at low temperatures leads to the air-sensitive coloured anions Qo" , ( = 1-6). The successive mid-point reduction potentials, 1/2, at -60°C are -0.82, -1.26, -1.82, -2.33, —2.89 and —3.34 V, respectively. Liquid NH3 solutions can also be used. " Ceo is thus a very strong oxidizing agent, its first reduction potential being at least 1 V more positive than those of polycyclic aromatic hydrocarbons. C70 can also be reversibly reduced and various ions up to... 

Solid-state [4 + 2] cycloaddition of fullerene C60 with condensed aromatics using a high-speed vibration milling technique [100]... 

Fullerenes. Fullerenes are a family of aromatic hydrocarbons, based on the parent buckminsterfullerene (108 that have a variety of very... 

Karttunen, A.J., Linnolahti, M., Pakkanen, T.A. and Pyykkd, P. (2008) Icosahedral AU72 a predicted chiral and spherically aromatic golden fullerene. Chemical Communications, (4), 465-467. 

The only reported X-ray structure of a it-bonded diiodine exists in the 12/coronene associate [75], which shows the I2 to be located symmetrically between the aromatic planes and to form infinite donor/acceptor chains. -Coordination of diiodine over the outer ring in this associate is similar to that observed in the bromine/arene complexes (vide supra), and the I - C separation of 3.20 A is also significantly contracted relative to the stun of their van der Waals radii [75]. For the highly reactive dichlorine, only X-ray structures of its associates are observed with the n-type coordination to oxygen of 1,4-dioxane [76], and to the chlorinated fullerene [77]. 

Nakamura Y, Suzuki KO-kawa M, Konno T, Nishimura J (2005) Photoreactions between [60] Fullerene and various aromatic tertiary amines. J Org Chem 70(21) 8472-8477... 

Polycyclic aromatic hydrocarbons such as fluoranthrene or Cso-fullerene are structures of great interest A straightforward entrance to analogues and partial structure, respectively, has now been developed by de Meijere and coworkers [89], using a combination of a Suzuki and a Heck-type coupling. Thus, reaction of 1,8-dibromophenanthrene 6/1-166 and obromphenylboronic acid 6/1-167 employing 20 mol% of the Pd° catalyst led to 6/1-168 and 6/1-169 in 54% yield as a Id-mixture (Scheme 6/1.45). 

Now and then, projectiles from outer space cause excitement and surprises, as in January 2000, when a meteorite impacted the frozen surface of Lake Targish in Canada. It was a new type of C-chondrite with a carbon concentration of 4-5%, and probably came from a D-type asteroid (Hiroi et al., 2001). More exact analysis of the Targish meteorite showed the presence of a series of mono- and dicarboxylic acids as well as aliphatic and aromatic hydrocarbons (Pizzarello et al., 2001). Aromatic compounds and fullerenes were detected in the insoluble fraction from the extraction this contained planetary helium and argon, i.e., the 3He/36Ar ratio was... 

The fullerene C o was used as the Unking agent for the synthesis of (PCHD-fc-PS)6 and (PS-fc-PCHD)6 star-block copolymers [154], The polymers were then aromatized with 2,3-dichloro-5,6-dicyano-l,4-benzoquinone, DDQ, in 1,2-dichlorobenzene to yield the corresponding copolymers containing poly(l,4-phenylene) blocks. In order to achieve high 1,4-isomer contents and to avoid termination reactions, the polymerization of CHD was conducted in toluene at 10 °C without the presence of any additive to yield products with low molecular weights. Coupling of the PCHD-fo-PSLi to C60... 

Cycloaddition with nitrile oxides occur with compounds of practically any type with a C=C bond alkenes and cycloalkenes, their functional derivatives, dienes and trienes with isolated, conjugated or cumulated double bonds, some aromatic compounds, unsaturated and aromatic heterocycles, and fullerenes. The content of this subsection is classified according to the mentioned types of dipolarophiles. Problems of relative reactivities of dienophiles and dipoles, regio- and stereoselectivity of nitrile oxide cycloadditions were considered in detail by Jaeger and... 

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