resumo
Among higher fullerenes that obey the isolated pentagon rule (IPR), there is an appreciable share of fullerenes with open electron shells. For a long time, this rule was used as a criterion for fullerene stability. Notwithstanding the IPR, fullerene radicals are unstable as pristine fullerenes but may be stabilized as their derivatives. Mainly, the molecules of such fullerenes contain phenalenyl-radical substructures. Here, for the first time, we found and theoretically investigated a new radical substructure of fullerene molecules of IPR isomer 7 (C-3v) of C-82 that bears two unpaired electrons and of IPR isomer 822 (D-3d) of C-104 with two equivalent substructures (four unpaired electrons). The fullerenes were obtained, and their molecular structures reliably characterized experimentally as endohedral derivatives. According to our computations, two hypothetical polyaromatic radical molecules C34H18 and C34H12, which are the models of the fullerene substructure, have the same open-shell triplet ground states. Peculiarities of distribution of spin densities of radical substructures are disclosed.
palavras-chave
STRUCTURAL-CHARACTERIZATION; PENTAGON; STABILITY; DERIVATIVES; SEPARATION; ISOMERS; C-74
categoria
Chemistry; Science & Technology - Other Topics; Materials Science
autores
Khamatgalimov, AR; Melle-Franco, M; Gaynullina, AA; Kovalenko, VI
nossos autores
Manuel Melle-Franco
Investigador Principalagradecimentos
This work was partially funded by Russian Foundation for Basic Research, research project No. 18-29-19110mk. M. Melle-Franco would like to acknowledge support from the Portuguese Fundacao para a Ciencia e a Tecnologia (IF/00894/2015) and from CICECO - Aveiro Institute of Materials, POCI-01-0145-FEDER007679 (UID/CTM/50011/2013). Authors thank Yekaterina Kovalenko (University of Florida) for her assistance in preparing the manuscript.