COMPARISON OF SPIN-DENSITY CALCULATION METHODS FOR VARIOUS ALKYL-SUBSTITUTED 9,10-ANTHRAQUINONE ANION-RADICALS IN THE SOLUTION-PHASE

EPR and ENDOR spectra were recorded for 2-methyl-9,10-anthraquinone (2 -methylAQ), 2-ethylAQ, 2-tert-butylAQ and 2,3-dimethylAQ anion radical s in the solution phase. The EPR spectra were simulated with the help of ENDOR data. The experimental isotropic hyperfine coupling constants (IHFCs) were compared with calculated values from semi-empirical INDO , spin-restricted AM1/CI and B3PW91 density-functional methods, The be st computational methods for the IHFCs were the semi-empirical AM1/CI method and the B3PW91 density-functional method with a large basis set .