Die Elektronenzustände von Perimeter‐π‐Systemen. II. Das Elektronenspektrum des trans‐15, 16‐Dimethyl‐dihydropyrens

The electronic spectrum and the polarisation of the transitions have been determined in the region from 15000 to 50000 cm−1 for the 2‐acetamino derivative of trans‐15, 16‐dimethyl‐dihydropyrene, whose spectrum resembles closely that of the parent compound and its di‐ethyl analogue. It is shown that the sequence of states is 1Lb, 1La, 1Bb, 1Ba, in agreement with theoretical predictions which were deduced from a configuration interaction model for the D2h‐π‐perimeter of these systems. The influence of inductive and hyperconjugative effects on the band positions and the band intensities has been discussed.