The journal of physical chemistry. A | 10 Oct 2018
D Bégué, A Dargelos and C Wentrup
The electronic structure and the rearrangements of the 2-phenylnitrene radical cation C6H5N.+ 2.+ have been investigated at DFT and CASPT2(7,9) levels of theory. The 2B2 state has the lowest energy of five identified electronic states, and it can undergo ring expansion to the 1-azacycloheptetetraene radical cation 4.+ with an activation energy of ca. 28 kcal/mol. Ring opening and recyclization provides a route to 5-cyanocyclopentadiene radical cation 8.+, which may undergo facile 1,5-hydrogen shifts. The 2-, 3-, and 4-pyridylcarbene radical cations 31.+, 35.+ and 39.+ interconvert with the phenylnitrene radical cation via azacycloheptatetraenes with activation barriers < 35 kcal/mol. The carbene-carbene and carbene-nitrene rearrangements, ring expansions, ring contractions, ring openings (e.g. to cyanopentadienylidene 28.+) and cyclizations taking place in all these radical cations are completely analogous to the thermal and photochemical rearrangements.
* Data courtesy of Altmetric.com