Vibrational Spectra of the Crystalline s-Tetrazines

The vibrational spectra of the crystalline s‐tetrazines show several infrared and one Raman band which have split into two Davydov components. These results are in agreement with the predictions of the correlation table. However, the magnitude of the splittings cannot be successfully explained by either the dipole–dipole or intermolecular hydrogen repulsion potentials. The intermolecular coupling mechanism is probably due to an interaction between the $\pi$ cloud of one molecule and the ring atoms of its neighbors.