Vibrational study of eight‐membered titanium and germanium‐containing siloxane rings

By a condensation reaction of tBu2Si(OH)2(L) with titanium and germanium tetrahalides several eight-membered titanium and germanium cyclosiloxane compounds were prepared in polar solvents. These were crystallized and identified by the usual physical techniques (1H, 13C and 29Si NMR spectroscopy, x-ray diffraction and mass spectrometry). Raman and IR spectra were also recorded, which confirmed the structure obtained by x-ray diffraction. The rings are well characterized by breathing modes which appear around 620–660 cm−1 and Si-O-M stretching-bending modes which appear around 950–1000 cm−1. The vibrational modes characterizing the tert- butyl group are weakly coupled with those of the heterocycles. The corresponding observed bands are close to those observed for (L).