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7618434 
Journal Article 
CALCULATION OF CHEMICAL-SHIFTS IN THE C-13 NMR-SPECTRA OF UNCHARGED MOLECULES AND THEIR PI-DIANIONS 
Filatov, IV; Sinyakov, GN; Shulga, AM; Guripovich, GP; , 
1990 
Yes 
Journal of Structural Chemistry
ISSN: 0022-4766
EISSN: 1573-8779 
PLENUM PUBL CORP 
NEW YORK 
244-249 
WOS:A1990HQ34600011 
The theory of average excitation energy has been used to calculate the chemical shifts of C-13 nuclei in the molecules of anthracene, [14]-annulene, [18]-annulene, pyrene, acepleiadilene, the cyclic complexes of porphyrins, and the pi-dianions of all these compounds. For anthracene and the annulenes the position of the chemical shifts correlates fairly well with the distribution of the pi-electronic charge both for the uncharged compounds and for the dianions. For the remaining compounds and their dianions the calculations take into account both the charge distribution and the differences in the average excitation energy for the individual carbon atoms and their changes in the dianions. Suggestions are made about the effect of the paramagnetic ring current in the dianions on the signals of C-13 nuclei lying both inside and outside the circumference of the current.