
%0 Journal Article
%A Collins, MJ 
%A Sternhell, S 
%A Tansey, CW 
%T N.M.R.-Studies of Bond Order in Azulene, Biphenylene and 1,6-Methano[10]annulene
%J Australian Journal of Chemistry
%D 1990/09/01
%V 43
%N 9
%P 1541-1546
%K 
%R https://doi.org/10.1071/CH9901541
%U https://www.publish.csiro.au/paper/CH9901541 
%X The 4J(H-C-C-Me) coupling constants of methyl-substituted derivatives, probes of bond order, have been used to examine the ground-state &#960;- electron distributions in azulene (1), biphenylene (2) and 1,6- methano [10] annulene (3). The experimental data obtained are in good agreement with theoretical predictions for biphenylene (2) and provide some evidence for &#960;-electron disproportionation towards the five-membered ring in azulene (1). The bond orders in 1,6-methano [10] annulene (3) obtained in this work are at variance with those predicted on the grounds of bond lengths. 
