Fullerene derivatives dimers

Giesa, S. Gross, J.H. Hull, W.E. Lebed-kin, S. Gromov, A. Kratschmer, W. Gleiter, R. C120OS the First Sulfur-Containing Dimeric [60]Fullerene Derivative. Chem. Commun. 1999,465-466. 

Irradiation of phenyliodonium salts lead to the formation of phenyl radicals. In the presence of C60 these radicals are efficiently trapped under formation of pheny-lated C6o derivatives, mainly the monoadduct. In reaction mixtures of C6o, phenyliodonium salts and spin traps like nitroso-tert-butane ( BuNO) or nitroso-durene (ND) no phenyl adducts with the spin traps could be observed after irradiation. This suggests that C6o is a more efficient scavenger for phenyl radicals than the spin traps [177], Other investigations yielded similar results, e.g., the photolysis of organomercury compounds in the presence of fullerenes leads to fullerene-derived radical adducts. These radical adducts can combine to form dimers that are thermally stable and accumulate in the samples [Eq. (7)] [178],... 

Figure 24 Formation of dimeric [60]fullerene derivatives from electroreduced 71.

Scheme 1.8. Controlled opening of the fullerene cage by self-sensitized photooxygenation of an azahomo[60]fullerene derivative and subsequent add-induced formation of a dimeric aza[60]fullerene.

At present, there is no firm experimental evidence for dipole-bound dianions. However, it is instructive to consider the results of multiply charged anions of fullerene derivative clusters discussed in Section VI. Tuinman and Compton reported the formation of doubly charged anions of C6o(CN)2 dimers, [C6o(CN)2]J, in electrospray ionization. The dipole moment of the C6o(CN)2 molecule in which the two CN radicals are bonded to two adjacent carbon atoms in Cgo is expected to be large... 

Up to now, two types of synthetic methods towards monomeric aza[60]fullerene derivatives have been developed Method (a) starting from non-azafullerene precursors and Method (b) starting from the dimer (C59N)2. 

Synthesis of Aza[70]fullerene Dimers (Cg9N)2 and Aza[70]fullerene Derivatives... 

Starting from 6-monotosyl CyD, many derivatives can be obtained, including aldehyde [19], iodide, chloride, azide, amino-, and alkyldiamino-CyDs. Dimeric yS-CyD receptors were synthesized from mono-6-iodo-CyD with a dithiol core, and they have potential as selective receptors of a-helical peptides [20]. Fullerene derivatives bearing a-, and y-CyD units were synthesized by the reaction of C o and peracetylated CyD 6-azides [21]. From 6-monoazide-yS-peracetylated CyD or... 

Radical reaction of [60]fullerene (459) with phosphites or phosphine oxide (460) mediated by manganese(III) acetate dihydrate in chlorobenzene under three dilferent reaction conditions afforded three different types of phosphorylated fullerenes hydrophosphorylated fullerenes (461), singly bonded fullerene dimers (462), and acetoxylated fullerene derivatives (463) (Scheme 114). In addition, interconversions among the three types of phosphorylated fullerene derivatives have also been investigated. ... 

The low solubility of fullerene (Ceo) in common organic solvents such as THE, MeCN and DCM interferes with its functionalization, which is a key step for its synthetic applications. Solid state photochemistry is a powerful strategy for overcoming this difficulty. Thus a 1 1 mixture of Cgo and 9-methylanthra-cene (Equation 4.10, R = Me) exposed to a high-pressure mercury lamp gives the adduct 72 (R = Me) with 68% conversion [51]. No 9-methylanthracene dimers were detected. Anthracene does not react with Ceo under these conditions this has been correlated to its ionization potential which is lower than that of the 9-methyl derivative. This suggests that the Diels-Alder reaction proceeds via photo-induced electron transfer from 9-methylanthracene to the triplet excited state of Ceo-... 

A review of Diels-Alder reactions of fullerenes with acyclic and cyclic dienes has been presented. The addition of substituted pyrimidine o-quinodimethanes (75) to [60]fullerenes yields novel organofullerenes (76) bearing a pyrimidine nucleus covalently attached to the Ceo cage (Scheme 26). The Diels-Alder dimerization of cyclopenta[/]phenanthrene (77) with isobenzindene (78) yields the dimer (79) in 85% yield (Scheme 27). Further evidence has been supplied to support an early reorganization of the r-network in the dimerization of 2-methoxycarbonylbuta-1,3-diene. The Lewis acid-catalysed Diels-Alder reactions of acrylate derivatives of new carbohydrate-based chiral auxiliaries with cyclohexadiene show excellent endo. exo... 

Most of the reactions of silicon or germanium organic compounds proceed photochemically via a radical mechanism or via a cycloaddition mechanism (Chapters 4 and 6). There are few examples of nucleophilic addition of RSi or RGe to Cgo [118,119]. Reaction of silyUithium derivatives RjSili or germyllithium derivatives RjGeLi with different alkyl- and aryl-substituents R yields mainly the 1,2-adduct 28 or the 1,16-adduct 29 1,4-addition and dimerization of two fullerene-units was also found as a minor pathway. One example is given in Scheme 3.15. 

This summarizes all the theoretical and gas-phase preparation work that has been done up to now with respect to aza[ 60] fullerene, except for the developments that led to the realization of actual bulk preparation of [60]- and aza[70]fullerene dimers and derivatives and the investigations of these products. This work will be described in detail in the remainder of this section. 

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