Wydział Chemii

Andrzej Bil

Zdzisław Latajka

Carole A. Morrison

2009

Journal of Physical Chemistry A

113

9891-9898

10.1021/jp9024798

Naukowa

Angielski

Artykuł

A series of ab initio calculations have been carried out to determine why the a,b- and c,c-isomers are the most commonly observed mono-oxides of C₇₀ in ozonolysis reactions, when existing calculations in the literature report that these structures are not the most stable conformations. We show that the a,b- and c,c-isomers are the two most stable structures on the C₇₀O₃ potential energy surface, which suggests that the reaction pathway toward oxide formation must proceed via the corresponding ozonide structure. From our calculations, we offer a mechanism for the thermally induced dissociation of C₇₀O₃ that share the first two steps with the general mechanism for ozonolysis of alkenes proposed by Criegee. We suggest further steps that involve C₇₀O₃ losing O₂ in its triplet or singlet state, thus leaving C₇₀O in its triplet or singlet state, respectively. A pair of products in their singlet states seems to be more likely for the decomposition of a,b-C₇₀O₃, which ultimately leads to the closed a,b-C₇₀O epoxide structure. For c,c-C₇₀O₃, the more thermodynamically favorable route is the triplet channel, resulting in the triplet open c,c-C₇₀O oxidoannulene structure, which may subsequently decay to the singlet ground state c,c-C₇₀O epoxide form. This finding offers an alternative interpretation of the experimental observations which reported an open d,d-C₇₀O oxidoannulene structure as the metastable intermediate.

https://doi.org/10.1021/jp9024798

https://www.acs.org/content/acs/en.html