The mechanism of the ozonolysis on the surface of C 70 fullerene: the electron localizability indicator study
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ORIGINAL PAPER
The mechanism of the ozonolysis on the surface of C70 fullerene: the electron localizability indicator study Andrzej Bil 1
&
Krzysztof Mierzwicki 2
Received: 1 December 2019 / Accepted: 23 February 2020 # Springer-Verlag GmbH Germany, part of Springer Nature 2020
Abstract The formation of C70O from C70O3 monomolozonide is a three-step process with the isomer dependent last step leading either to c,c-C70O epoxide or d,d-C70O oxidoannulene. The process involves the open intermediate (first O–O then Cc–Cc/Cd–Cd bonds broken), oxidoannulene-like structure intermediate (new Cc–O/Cd–O bond formed) and finally the oxide product. On the formation of c,c-C70O isomer, the final release of O2 is followed by the restoration of Cc–Cc bond, which stabilizes the product. Neither Cd–Cd bond is restored nor the total energy essentially lowered upon d,d-C70O formation. At all steps of the studied process, the four CC bonds adjacent to Cc–Cc or Cd–Cd bond, respectively, play a crucial role donating or withdrawing the necessary electron density. C70(O)O2 products, with O2 bridging one of the bonds adjacent to the parent Cc–Cc/Cd–Cd one, may compete with the oxide products. The OO bond in such structures is weak as suggested by its low electron population. For both c,c-C70O3 and d,d-C70O3, the shape of the potential energy surfaces (0 K) and the related, reported earlier, room temperature–free energy surfaces differ. Keywords Molozonide . Epoxide . Oxidoannulene . ELI-D . Quantum chemical topology
Introduction Due to as many as five non-equivalent types of carbon atoms, C70 has a more complicated chemistry than C60 fullerene (Fig. 1) [1, 2]. The resultant eight types of CC bonds allow eight possible monoadducts formed by C70 and O3, while the actual products are formed over a,b and c,c bonds, which are known to exhibit features similar to a double bond [3–6]. The fullerene ozonides (precisely, monomolozonides) were the subject of experimental and This paper is dedicated to Professor Zdzislaw Latajka, on occasion of his 70th birthday in recognition on his vital research contributions. This paper belongs to the Topical Collection Zdzislaw Latajka 70th Birthday Festschrift Electronic supplementary material The online version of this article (https://doi.org/10.1007/s00894-020-4333-8) contains supplementary material, which is available to authorized users. * Andrzej Bil [email protected] 1
Faculty of Chemistry, University of Wrocław, 14 F. Joliot-Curie, 50-383 Wrocław, Poland
2
Wrocław, Poland
theoretical study [3–11]. When kept in the dark, the two known ozonides decompose thermally to form stable epoxides of a related structure, i.e., a,b-C70O and c,c-C70O, with the oxygen atom bridging the parent CC bond. The photolysis of the ozonides opens more complicated reaction channels, with several unstable intermediates. The intermediates, which exhibit oxidoannulene structure, with the CC bond broken, convert eventually to one of the stable epoxides [3]. As demonstrated in paper [6], for Ca–Cb and Cc–Cc bond
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