On the Charge Distribution and Electron Affinity of the OH− Ion in LiOH

The value previously published by Hon and Bray for the quadrupole splitting of the lithium resonance of LiOH powder has been used to deduce the electrostatic field gradient at the lithium site. Using a point-charge model, it is shown that the accepted structure (derived by Dachs using neutron-diffraction and x-ray techniques) leads to the two alternative, but plausible values −0.21e and +0.35e for the charge on the hydrogen atom of the hydroxyl ion. A calculation of the lattice energy for these two values of charge gives 232.5 and 282.9 kcal/mole, respectively. The accepted value is 233±1 kcal/mole, allowing us to decide in favor of −0.21e as the charge on the hydrogen atom. Other possible structures consistent with the crystal symmetry lead to unrealistic values of lattice energy. If allowance is made for the polarization energy of the hydroxyl ion in the LiOH lattice, we deduce an electron affinity of the ion of 46.5±4 kcal/mole.