Gas-Phase Reactivities and Interchromophoric Effects in 1,n-Dicarbazolylalkane Cations and Related Species

Article abstract of DOI:10.1021/jo00025a015

The behavior of gaseous cations derived from electron ionization (20 and 70 eV) and methane chemical ionization (CI) of 1,n-dicarbazolylalkanes 1a-5a (where n = 1-5 methylene units, respectively) and the corresponding 3-nitro derivatives 1b-5b was examined using mass spectrometry.An iminium ion (m/z 180) is the major fragment from all 1-5 examined with the exception of 4a, for which CI affords predominantly a pyrrolidinium ion (m/z 222) by displacement of carbazole.Compounds 1a and 1b exhibit little *+ and + and undergo the most extensive fragmentation.Ethylated iminium ion (m/z 208) is observed from both 1a and 1b under CI conditions, indicating operation of an interannular hydrogen shift.Compound 3a fragments least, consistent with an exceptional, although small, stabilization for the parent ions of this derivative.