Die Electronenzustände von Perimeter‐π‐Systemen: III. Das Elektronenspektrum des 1,6‐Methano‐[11] annulenium‐Kations

Abstract
The electronic spectra and the polarisation of the transitions have been determined for the 1,6‐methano‐[11] annulenium cation III and the 4,6‐dimethyl‐1,2‐benzotropylium cation IV. The observed sequence of polarisation of the prominent bands corresponding to the lowest electronically excited states is in agreement with the predictions derived from molecular orbital models of the PARISER‐PARR‐POPLE type. The influence of partial conjugation between the bridged centre and of the inductive effect of the methylene group in III has been investigated.