Direct correlation between lithium cation and carboxyl anion in highly concentrated aqueous solution

Abstract

Abstract Time-of-flight neutron diffraction measurements have been carried out for aqueous solutions at about 20 mol% CD3COOLi. The isotopic difference method has been used to determine the distribution functions around Li+ by changing the isotopic composition of Li nuclei. A model for the environment around Li+ is proposed from analysis of the first and second peaks in . We propose direct correlations between Li+ and two oxygen atoms in CD3COO- on the grounds of a deficiency in water molecules hydrated around Li+. Three oxygen atoms of water molecules and two oxygen atoms of an acetate ion are located at 1·96 Å and at ca. 2·7 Å, respectively. Thus, the hydration number of Li+ is 3·0 ± 0·3: an anion of CD3COO- is located across and over the first hydration shell.