Fullerene anion

Kuhn s carbanion analogues, [44 ], [45 ] and [46 ], have recently been synthesized, and the precursor hydrocarbons [44]-H, [45]-H and [46J-H dissociate into the respective anions in DMSO to show deep blue colours without any added base (Kinoshita et al., 1994). A fullerene anion, Bu Qb [47 ], has also been obtained as a stable carbanion (Fagan et al., 1992) its lithium salt has been isolated in the form Li [47 ]-4MeCN or Li [47"]-3-4THF. Several stable all-hydrocarbon anions of precursor hydrocarbons with low pKa values ( 7) are listed in Table 2, along with their oxidation potentials, ox-... 

A possible explanation of this conductivity assumes that polymerization of fullerene anion-radicals results in the formation of a long conjugated chain. This is why the conduction electrons can move along the chain. 

In solid-state NMR [1,51-64], the magnetic coupling between the fullerene anions has to be taken into accoimt. In the case of metal intercalated fullerides that have metallic properties a contribution from the conduction electrons must be added, a phenomenon called the Knight shift . Even if this additional shift affects the C-chemical resonance, the correspondence between extended and discrete systems of comparable Cjq oxidation state is quite close [1]. 

In contrast to highly stable and prolific fullerene anionic species, fullerene cations are rare. The first fullerene cation was prepared in 1996 by Reed and co-workers500 by single-electron oxidation of C76 to form radical cation C76 + isolated in solid form as the CBnH6Br6 salt [Eq. (3.56)]. The cation was identified in solution by a characteristic visible-near-infrared absorption (Amax = 780 nm), FT-IR and EPR spectroscopy. C60 + was generated in an analogous way later.501 Reed et al.501 also succeded in... 

Photoinduced electron transfer from the amine to C6o to yield a radical ion pair is suggested to be the initial step for the formation of 54a-b. This is followed by deprotonation of the amine cation by the fullerene anion to give an a-aminoalkyl and HC6o radical pain [134], Subsequent combination of the radical pair leads to the final product. Formation of 55 is likely to be initiated by PET from 54b to C6o. This is then followed by successive intermolecular proton transfer, hydrogen abstraction, and ring closure to give l,2-H2C6o and 55 (Scheme 21). 

Photoionization of doped fullerene anions Coulomb confinement resonances 38... 

Figure 11 Nondipole photoelectron angular asymmetry parameter y A ( >) for Is photoionization of free Ne, Ne from neutral Ne Cgo as well as Ne from the fullerene anion Ne q0 (z < 0) [28], as indicated.

In fullerene anions C%q, the n electrons outside closed shells occupy /lu triplet electronic states. Jahn-Teller (JT) coupling between these states and 5-fold h-type vibrations has important consequences for many properties of the fullerene anions. It is therefore important to understand the JT effect experienced by these ions from a theoretical point of view. We will study the cases of n = 2 and 4, where the lowest adiabatic potential energy surface is found to consist of a two-dimensional trough in linear coupling. The motion of the system therefore consists of vibrations in three directions across the trough and pseudo-rotations in two directions around the trough. Analytical expressions for states of the system that reflect this motion are obtained and the resultant energies determined. 

The aromatic character of fullerene anions can be better understood by monitoring the local ring currents of the 5-membered rings (5MRs) and 6-membered rings (6MRs) in... 

More light can be shed on the effect of geometry and symmetry on fullerene anions by studying their 13C NMR chemical shifts that are affected by both charge distribution and ring currents. 

The tiu configuration was also explored in the fullerene anions Ceo - For this system the orbital disproportionation (see Sect. 5) was first revealed by Ceulemans, Chibotaru, and Cimpoesu [25,26] by direct estimation of the electron interactions in the distorted configuration in order to explain the origin of conductivity in the alkaline-doped fullerides A3C60. 

D INADEQUATE spectra have been used to establish the structure of a series of P-propiothiolactones, of a series of precursor polymers towards poly(p-phenylene vinylene), of l,16-di(2-carbomethoxy-2-propyl)-l,16-dihy-dro[60]fullerene and of the fullerene anion. One-bond carbon-... 

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