ISSN:
0030-4921
Keywords:
Chemistry
;
Analytical Chemistry and Spectroscopy
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
Notes:
The proton NMR spectra of the carbanions of xanthene [XH]- and thioxanthene [TxH]- have been recorded and interpreted. Paratropism in the central rings of [XH]- and [TxH]- is inferred from a comparison of the chemical shifts with those of the carbanion of 9,10-dihydroanthracene [AH]-. The contributions to the chemical shifts arising from n-electron excess charges, local dipoles and magnetic anisotropies are discussed. Numerical values for the various ring currents have been estimated by a least squares analysis of the observed chemical shifts after applying corrections for the excess charge effect. The results point to a strongly increasing paramagnetic ring current in the central ring in the order [AH]-, [TxH]-, [XH]-.
Additional Material:
3 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/mrc.1270060413
