Knowledge Bank

“Proof of the structure of molecular complexes has, in the past, been obtained by analyses of the infrared, Raman, or ultraviolet spectra. Such analyses have been made on the basis of slight perturbations of the spectra of the component parts of the complex as the complex is formed from these parts. This investigation was carried out to put this type of analysis on a firmer foundation by obtaining the symmetry of some solid complexes for which independent symmetry determinations can be, or have been, made. The infrared spectra of the complexes of $SbCl3$-dioxane, $AgClO4$-dioxane and $AgClO4$-benzene indicate that the symmetry, as deduced by this method, is dependent on the physical state, that it predicts a symmetry for the $SbCla$-diaxane complex which is difficult to explain, and that the known symmetry for the $AgClO4$-benzene complex cannot be deduced by the method of perturbations. The interaction in the latter case is apparently so strong that the infrared spectrum no longer has much relationship to the summation spectra of the component parts of the complex.”