Vibrational properties of siloxene: Isotope substitution studies

The vibrational properties (IR and Raman) of the two-dimensional sheet polymer siloxene (Si₆O₃H₆) are studied using ¹H - ²H and O - ¹⁸O substitution. While the stretching vibrations shift as expected under the substitution experiments, the low frequency bending vibrations shift anomalously. In particular, the lines previously attributed to a silicon phonon mode (514 cm^-1 in IR and 496 cm^-1 in Raman) show the typical H-D isotope shift in IR, but appear to harden to 575 cm^-1 in Raman scattering. These results contain important information about the siloxene microstructure.