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Title: Magnetic circular dichroism of an unaromatic planar [8]annulene
Abstract

An overview of magnetic circular dichroism (MCD) spectroscopy of π‐electron systems derived from a 4N‐electron perimeter is provided, with emphasis on the hypothetical parent cycloocta‐1,3,5,7‐tetraene ofD8hsymmetry (1) and itsD4hsymmetry derivatives. UV‐visible absorption and MCD spectra of2, aD4hsymmetric cycloocta‐1,3,5,7‐tetraene planarized by the effect of 4 bicyclo[2.1.1]hexeno units fused to its 8‐membered ring, are reported and interpreted. The perimeter model is applied to obtain an understanding of the nature of electronic states in1and2and to predict general trends in the spectra. The electronic excitation patterns are found to be different in the antiaromaticD8hand unaromaticD4hspecies, and their states cannot be unequivocally correlated. The results of time‐dependent density functional theory and extended multistate complete active space second‐order perturbation theory (XMS‐CASPT2) computations agree with the algebraic perimeter model analysis and reproduce the spectra of2well, including three of the four observed MCD signs of A and B terms.

 
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NSF-PAR ID:
10065696
Author(s) / Creator(s):
 ;  ;  ;  ;  ;  ;  ;  ;  ;  
Publisher / Repository:
Wiley Blackwell (John Wiley & Sons)
Date Published:
Journal Name:
Journal of Physical Organic Chemistry
Volume:
31
Issue:
8
ISSN:
0894-3230
Format(s):
Medium: X
Sponsoring Org:
National Science Foundation
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