Calculated optimized structures and hyperfine coupling constants of some radical adducts of α-phenyl-N-tert-buthyl nitrone in water and benzene solutions

The ground state optimized structures of some radical adducts of α-phenyl-N-tert-buthyl nitrone (PBN) in water and benzene solutions were calculated by using DFT (B3LYP, B3PW91 and PBEPBE) and HF methods with 6-311++G(d, p), 6-31G(d, p) and LanL2DZ levels. As trapped radicals, F, Cl, Br, H, OH, CN, NCO, and N3 were used. The calculated isotropic hyperfine coupling constants of all the trapped radicals were seen to be in good agreement with the corresponding experimental data. The hyperfine coupling constant due to the β proton of nitroxide radical was seen to be effected with the opposite spin density of oxygen nucleus bonded to the nitrogen. From all the calculated data it was concluded that for hyperfine calculations the DFT method is superior relative to the HF method. Also the geometrical parameters for the ground state optimized structures of all the radical adducts were listed, and the binding energies of all the trapped radicals were obtained.