Knowledge Bank

“With the use of an evacuated infrared spectrometer capable of making measurements to $55cm-1$ absorption spectra have been measured for the ions $I3-$, $I2Br-$, $IBr2-$, $IBrCl-$, $ICl2-$, and $I2Cl-$ present in various cesium, rubidium, and tetramethyl ammonium salts. Bending and stretching vibrations have been observed and the resulting force constants will be discussed in relation to the unusual bonding found in these compounds. Comparison will also be made with the bonding involved in the pridinium dihalides and the xenon and krypton fluorides. The observation of both $\nu 1$ and $\nu 2$ for several of the XYX type polyhalideions supports the available X-ray evidence that these ions are unsymmetrical in some compounds. In addition predictions can be made regarding the symmetry and structure of several polyhalide salts for which X-ray measurements are not available.”