Fullerenes nomenclature

A final question to be addressed is that of the limits of the descriptor system with regard to the structures it can be applied to. In a stricter sense, it should be valid for all fullerenes and their derivatives having a cage framework that is unaltered with respect to the number of atoms and their coordination within the core. In practice, however, as various core-modified fullerenes have been synthesized,41 49 it may appear convenient to apply it to all compounds that are relatively closely related to the carbon spheres and to which fullerene nomenclature can be easily applied. 

In another nomenclature recommendation it was suggested that fullerenes be named in the same way as annulenes, for which the number of C-atoms is indicated in square brackets in front of the word [4]. For fullerenes the number of C-atoms is accompanied by the point group symmetry and by the number of the isomer (using capital Roman) in cases were there are more than one. This is especially important for higher fullerenes. Thus, for Buckminsterfullerene the full description is... 

To facilitate discussion of these somewhat more complicated fullerenes with one or more atoms inside the cage, a special symbolism and nomenclature was introduced [66]. Thereby the symbol is used to indicate the atoms in the interior of the fullerene. All atoms listed to the left of the symbol are located inside the cage and all atoms to the right are a part of the cage structure, which includes heterofullerenes, e.g. C59B. A Cgg-caged metal species is then written as M Cgg, expanded as metal at Cgg . The corresponding lUPAC nomenclature is different from the conventional M C representation. lUPAC recommend that M C be called [rt]fuUerene-incar-lanthanum and should be written iMC [4]. 

Many elements can give rise to more than one elementary substance. These may be substances containing assemblages of the same mono- or poly-atomic unit but arranged differently in the solid state (as with tin), or they may be assemblages of different polyatomic units (as with carbon, which forms diamond, graphite and the fullerenes, and with sulfur and oxygen). These different forms of the element are referred to as allotropes. Their common nomenclature is essentially trivial, but attempts have been made to develop systematic nomenclatures, especially for crystalline materials. These attempts are not wholly satisfactory. 

Nomenclature is not a static subject. It changes as new kinds of compound are synthesised and new procedures and devices have to be invented. Fullerenes are a case in point, and their detailed nomenclature and numbering are currently (1997) under discussion. Even established procedures are continuously being reviewed and revised, but the principles established in this survey are likely to remain recommended for the foreseeable future. 

The absence of a formal nomenclature al this juncture is accompanied by a somewhat fuzzy chronology pertaining to the discovery and early research on ihe fullerenes. However, the isolation and confirmation of the CHI all-carbon molecule sans any dangling bonds, as first conjectured in 1985. was pivotal to subsequent research. 

To identify modified fullerenes a numbering system for the carbon atoms is necessary. According to the IUPAC nomenclature [209], based on the proposal of Taylor in 1993 [210], the carbon atoms are numbered as outlined for C6o and C70 in Fig. 29. 

The accepted nomenclature is used in the work. An individual fullerene molecule is referred to as "fullerene". A crystal from fullerene molecules is referred as "fullerite". 

As well as new properties of these molecules that have come to light with the discovery and nomenclating of the higher lullerenes and fulleranes, an extension that is unfathomable using traditional nomenclature, but is readily explained using beta bonds is next described when some of the carbon atoms are replaced by metal atoms in various of the smaller fullerenes. These molecules, which historically are not in the domain of... 

Whereas neither I.U.P.A.C. nor nodal nomenclature bother to extend their system to what is, at present, a very small group of topologically restrained compounds, the proposed system allows for a simple extension to the set of catenanes and rotaxanes. Also, one may readily adapt this system to canonically naming endothelial compounds, such as endothelial fullerenes, etc. Moreover, extension to "chemical" knots having multiple interconnections and windings, without having to resort to the tedium employed by Schill to extend I.U.P.A.C. nomenclature to these compounds, is straightforward. 

The evolving domain of radial, as well as linear, addition of modules to form an expanding moiety, in a manner akin to the development of polymers, referred to as "dendrimers", is examined and nomenclated The direct inclusion of topology in the description of isomers, once a very insignificant part of chemical nomenclature, is now a factor to be reckoned with, not only for the small class traditionally referred to as "topological" (including catenanes, rotaxanes, and knots), but also as new compositions of matter, such as the endothelial fullerenes, are formulated. 

Nomenclature for the CWrL and Cbo-Dswr,) fullerenes (IUPAC Recommendations, 2002) 02PAC629. 

Before turning toward the structural features of fuUerenes, it is necessary to find a convention allowing for their unambiguous description in a simple and conceivable way. Unfortunately, the lUPAC nomenclature not really has a catching suggestion here the systematic name for the most common fullerene consisting of 60 carbon atoms is ... 

As wUl be seen later, there are also fuUerenes with one or more carbon atoms being substituted by other elements. In fuUerene nomenclature these molecules are described by prefixing to the name the designating syllable for the respective hetero atom, for ejample, aza[70]fullerene C69N, bis(aza[60]fullerene) (C59N)2, bora[60]fuUerene C59B, or phospha[60]fuUerene C59P. 

Many problems in electronic structure, cage isomerization, and fullerene growth become accessible when a complete set of isomers is available for the testing of ideas. A nomenclature based on the spiral code forms part of the lUPAC proposals on systematic naming of the fullerenes when labels based on atom count and symmetry... 

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

Most of the exohedral fullerene derivatives of preparative importance are formed by one or several formal 1,2-additions to [6,6]- or [5,6]-bonds. For a suitable discussion of the regiochemistry of such fullerene derivatives it is very valuable to introduce a simple and clear site labeling system, which allows facile description of the constitution of a given fullerene derivative. We first introduced a very descriptive nomenclature [177,188] for the assignment of the relative positional relationships (like ortho, meta and para in benzene chemistry) of addend carrying bonds in Cgg derivatives with labeling the corresponding bonds as cis-n (n = 1 -3), e, e", trans-n (n= 1-4) (Fig. 15). 

This nomenclature is increasingly being used in fullerene literature. However, it can only be applied to [6,6]-bonds within Cgg-derivatives. But, since, for example, the regiochemistry of multiple [5,6]-adducts of Cgo and multiple adducts of higher fullerenes already started to develop, we also introduced a general site labeling algorithm, which can be applied to [5,6]- and [6,6]-positions of all fullerenes and their derivatives [189]. 

The nomenclature that has been used for fullerenes, fullerene derivatives, and heterofullerenes, has been until now rather haphazard. In this review, we will generally try to comply with the latest lUPAC nomenclature, as described in the article by Godly and Taylor [22]. 

Carbohydrates, Recognition of, p. 169 Carbonic Anhydrase Models, p. 178 Carcerands and Hernicarcerands. p. 189 Cation-n Interactions, p. 214 Cavitands, p. 219 Chiral Guest Recognition, p. 236 Classical Descriptions of Inclusion Compounds, p. 253 Classification and Nomenclature of Supramolecular Compounds, p. 261 Clathrate Hydrates, p. 274 Conzplexation of Fullerenes, p. 302 Concepts in Ciystal Engineering, p. 319 Crown Ethers, p. 326 Cryptands, p. 334 Cryptophanes, p. 340 Cyclodextrins, p. 398... 

Information about lUPAC nomenclature and representation of fullerenes and related compounds... 

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