MO STUDY OF METHYLENIMINE IN THE LOWEST EXCITED-STATE - COMPARISON WITH CH2=CH2, NH=NH AND CH2=O

The structure of methylenimine (CH2NH) in the lowest excited state is calculated using the singly excited configuration interaction (SECI) procedure. The result shows that the lowest triplet state of methylenimine of π → π* character is expected to have a stable structure twisted 42° about the CN bond and that the singlet n → π* excitation leads to a 90° twist of the NH bond and flapping of the CH2 part. This structure gives immportant information on the mechanism of photoisomerization of imine in the n → π* singlet state. The excited states of the isoelectronic species, ethylene,, diimide and formaldehyde, are compared with that of methylenimine. © 1979.