H-1, C-13, AND O-17 ISOTROPIC AND ANISOTROPIC HYPER-FINE COUPLINGS FOR THE PLASTOSEMIQUINONE ANION-RADICAL

Hybrid density functional calculations (B3LYP) are performed for the p lastosemiquinone anion radical in its free form and in models to simul ate its hydrogen bonding environment in alcohol solvents. H-1, C-13 an d O-17 isotropic and anisotropic hyperfine couplings are calculated. T he effect of hydrogen bonding interactions in the alcohol solvent mode l is shown to lead to a redistribution of spin density from the oxygen atoms to the carbon atoms of the carbonyl groups. H-1 calculated hype rfine couplings are compared with previous assignments based on ENDOR measurements. A rearrangement of the experimental assignments for the methyl group couplings is indicated and a reinterpretation of the H-1 hydrogen bonding data is presented.