Infrared Bands from Alkali Ion Motion in Solution

Abstract

The infrared spectra of the $Li^{+}, Na^{+}$, and $K^{+}$ salts of $Co(CO)_{4}^{-}$ and $Mn(CO)_{5}^{-}$ in tetrahydrofuran solution now have been examined in the region $4000-33 cm^{-1}$. Bands have been found which are associated with the motion of the alkali metal cation in the solution. Considerable effort has been extended to eliminate impurities as the source of the observation. Frequency data in other regions of the spectra, and equivalent conductance data give information relative to the nature of the ion aggregate. The frequency data have been used to compute the forces at the alkali ion in the solution. These forces are compared with those computed on an electrostatic basis, and comments will be made regarding the nature of the aggregate.