Non-existence Fullerene Compounds
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Non-existence Fullerene Compounds Roberto Salcedo Instituto de Investigaciones en Materiales, UNAM. Circuito exterior s/n, Ciudad Universitaria, Coyoacán 04510, México D.F. Abstract: A brief summary about the research lines of our group is presented. The common factor in all the propositions is the fullerene in a chemical reactive role. The chemistry proposed is novel and can yield interesting results. 1. Introduction: Fullerenes have been the object of intensive research for the last twelve years [1-3]. There are several features to consider when studying these fascinating molecules because they can be approached from a physical, chemical or even biological point of view, and during their short life (as a full characterized species) they have been found to be useful or applicable in several different fields; for example electronics, communications or even pharmacy. One important feature that strongly accounts for this diversity is the particular and novel reactivity of these species [4]. In spite of their ambiguous aromatic character [5] (which itself is an important topic for study), the reactions of fullerenes are somewhat different to those of classic polyaromatic hydrocarbons or even those pertaining to normal olefins. In this sense, it is relatively easy to find sigma substituted organic derivatives [6]; endohedral [7] and also exohedral [8] organometallic complexes, adducts of biomolecules [6] or porphyrin and also phtalocyanine derivatives [9]. Theoretical calculations have been very useful for this research [4]. The precise models for new species and comparisons with experimental and spectroscopic data have been demonstrated to represent a very important tool for the design, search or application of the large quantity of fullerene derivatives known today. Our research group has been working on the design of very different fullerene compounds. We have proposed new species that have been theoretically studied and we have found thermodynamic evidence of stability, suggesting that many of these new molecules can be prepared and may even have potentially important applications. Our propositions are divided into five main groups: a). Fullerenocene. b). C80 exohedral η6 compounds. c). Cycloadditioned fullerene compounds. d). Phenyl-fullerene. e). Symmetrically nested (matrushka) endohedral fullerenes. 2. Results. a). Fullerenocene [10]. Di-benzene-chromium [11] (figure 1) is a well known π compound. This type of molecule was previously considered to be a very important example of an organometallic compound, where the bond between the metal atom and the aromatic fragments is formed only
by π interactions. In another context, the aromaticity of fullerenes has been the object of very different studies and there is no conclusive argument to indicate whether or not they are aromatic. Thus it is not possible to establish the interaction between all the carbon atoms of a six member fullerene ring and a metal atom (or ion), indeed no definitive experimental study exists where a η6 fullerene organometallic complex has be
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