Total 2p? Spin Density Mapping as a Function of Hydrogen Bonding Involving an Anion Radical

Article abstract of DOI:10.1021/j100378a022

EPR spectra will utilized to generate a "map" of the 2p^? spin density distribution in the indanetrione anion radical as a function of hydrogen bond formation between this anion radical and water. ¹⁷O substitution followed by computer simulation of natural abundance ¹³C splittings and enriched ¹⁷O splittings allowed measurements of the spin densities on each atom of the radical.The four observable ¹³C hyperfine splittings were found to vary upon hydrogen bond formation, and the equilibrium constant for hydrogen bonding (C9H4O3^.- + HOH = C9H4O3^.-...HOH) could be evaluated from the variation in these splittings.However, the 2p^? spin densities on only three of the seven nonequivalent positions are perturbed.The 2p^? spin densities on the two oxygen atoms are invariant even though the formation of the hydrogen bond involves the oxygen atoms.