ИСТИНА

Since its discovery in 1999, Sc3N@C80 with icosahedral Ih-C80 cage remains the third mostabundantly produced fullerene (after C60 and C70) and the most abundant endohedral metallofullerene, which results from its high synthetic yields and improved kinetic stability comparable to pristine fullerenes rather than to the other common endohedral molecules. Its potential applications include photovoltaics (components of bulk heterojunction solar cells, organic light-emission diodes and fieldeffect transistors) and medicine (MRI contrast agents, antioxidants, europrotective agents). Virtually any practical application of fullerenes requires their chemical erivatization in order to increase solubility, create a linker, or to tune or enhance certain electronic properties. The influence of chemical modification on the electronic and structural properties of fullerenes is, therefore, of considerable importance. Of special interest is exohedral derivatization of endohedral fullerenes, which is capable to alter the interactions of the endohedral cluster with the carbon cage and to exert orienting effects on the former. In this regard, incorporation of CF2 bridge provides an interesting test case of carbon cage asymmetrization in terms of geometry and reactivity with fine tuning of boundary levels but without actual withdrawal of any carbon atoms from the p-system. The present study addresses the effects of exohedral CF2 functionalization of Sc3N@Ih-C80 molecule on the structural and electronic properties. We present DFT-based analysis of the clustercage interactions, charge and spin distribution in various charge states, structure of boundary levels, and electronic characteristics (IP, EA, HOMO-LUMO gap). We demonstrate that both [5,6]- and [6,6]- isomers of Sc3N@C80 tend to have open structure, and insertion of CF2 moiety into the fullerene sphere significantly affects electron density distribution, restricts cluster rotation inside the cage (compared to almost unhindered reorientations in pristine Sc3N@C80), and must give rise to regioselective effects with regard to further cage functionalization. The work is supported by RFBR 15-03-05083.