Raman and infrared spectroscopic studies of the low- and high-temperature forms of octahalo cyclic phosphazene tetramers, P₄N₄C_l8 and P₄N₄F₈

Abstract

Based on a study of the Raman and infrared spectra, normal vibrations of the low-temperature skew-tub (S₄) and high-temperature C_i or C_2h (skew-chair) forms of P₄N₄Cl₈ have been assigned. A temperature variation study of the Raman spectra has shown the coexistence of both the forms of P₄N₄Cl₈ in the phase transition region. Preliminary assignments of the Raman and infrared spectra of the low- and high-temperature forms of P₄N₄F₈ are presented. One of the low-frequency Raman modes softens through the phase transition of P₄N₄F₈ at 199 K.