Fullerene cationic

Recent progress in preparation and study of alkylated fullerene cations RC6o+ and RC o+ as long-lived species are examined by T. Kitagawa in Chapter 12. Chapter 13 by C. J. A. Mota and co-workers examines the formation of the bicyclobutonium cation via cyclopropylcarbinyl chloride over solid acid catalysts. 

Generation, Stability, and Reactions of Alkylated Fullerene Cations... 

Cationic species of fullerenes have long been considered to be difficult to prepare, based on the well-known resistance of C , toward oxidation. However, reliable methods are now available for the preparation of alkylated fullerene cations RC60+ and RC70+ as long-lived species, allowing their structures and properties to be investigated in detail. Precise evaluation of their thermodynamic stabilities revealed that these cations have stabilities comparable to the terf-butyl cation. 

There are limited number of reports of the observation and isolation of functionalized fullerene cations. The monoalkylated [RC6o+(73,74), C12CH-C70+ (75), and (EtO)2P+(OH)CH2-C60+ (76)], monoprotonated [HC60+ (7-2,77)], and pentaarylated [Ar5C60+ (75)] fullerene cations have thus far been prepared as stable solutions or isolated as solids (Figure 1). 

Alkylated Fullerene Cations under Stable Ion Conditions... 

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... 

Birkett and co-workers506 have applied a different approach using chloride abstraction with A1C13 from Ar5C6oCl to generate pentaarylated fullerene cations... 

In this case, the photoionization cross section possesses no Coulomb confinement resonances. This is because the fullerene cation s potential Vcti(r) seen by an outgoing photoelectron does not exhibit a Coulomb potential barrier (see Figure 10 for z = +5 for illustration purposes). 

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