DIRECT SPECTROSCOPIC STUDY OF SILAOLEFINS. VIBRATIONAL FREQUENCIES OF R2Si=CD2 (R = CH3, CD3) IN AN ARGON MATRIX

Article abstract of DOI:10.1016/0022-328X(84)85163-3

As a continuation of studies on Si=C bond species, the silaethenes (CH3)2Si=CD2 and (CD3)2Si=CD2 have been generated by vacuum pyrolysis of the corresponding silacyclobutanes with totally deuterated rings.The silaethenes are stabilized in argon matrices at 12 K and characterized by IR spectroscopy.The following vibrational bands of the silaethenes have been revealed by using warm-up experiments (to 40K) and through variations of the pyrolysis conditions: (CH3)2Si=CD2 508.0, 535.3, 617.1, 776.5, 819.8, 895.1, 1117.5, 1251.0, 1259.5 cm^-1; (CD3)2Si=CD2 501.6, 651.2, 732.0, 866.5, 1002.5, 1005.0, 1028.0, 1112.0 cm^-1.A comparison of these values with computed vibrational frequencies of the silaethenes indicates that the ν(Si=C) vibration corresponds to two bands in the spectrum of each silaethene, namely 895.1 and 1117.5 cm^-1 for (CH3)2Si=CD2, 866.5 and 1112.0 cm^-1 for (CD3)2Si=CD2.Within each pair, the band with the higher wave number corresponds to a larger contribution by ν(Si=C).