M. K. WONG,W. J. MCKINNEY, AND A. I. P a ~ o v
56
Spectroscopic Studies of Ionic Solvation. VIII.
Alkali Metal
Salts in A.cetone Solutions
b,y Ming Keong Wong, William J. McKinney, and Alexander I. POPOV*~ Department o j Chemistry, Michigan State Uniuersity, East Lansing, Michisan 48883 (Received August 13, 1070) Publication costs assisted by the National Bcience Foundation
Infrared and proton nmr studies were carried out on solutions of lithium and sodium salts as well as on potassium thiocyanate in acetone and in acetone-nitromethane solutions. Cation-acetone vibrational bands were identified at 425 f 3 cm-l for Li+, 195 f 4 cm-l for Na+, and 148 f 5 cm-l for Kf. The dependence of these frequencies on isotopic substitution of the solvent (&-acetone) and of the solute (*Li)indicate that the observed vibrations clearly involve both the cation and the solvent. The observed frequencies showed anion dependence in the case of LiCl and LiBr which indicates that the respective halide ions participate in the observed vibration. Both the infrared and the nmr measurements indicate that the solvation number of the lithium ion is 4 in acetone solutions and in acetone-nitromethane solutions as long as the acetone/Li+ mole ratio is 24. Below this value the anions penetrate into the solvation shell of the cation.
Introduction
water content of the purified product, as determined by the Karl Fisher titration, was
