Silaethene H_2C=SiH_2: Millimeter Wave Spectrum and Ab Initio Calculations

摘要

While silaethenes CR~1R~3=SiR~3R~4 that are kinetieally stabilized by bulky ligands R~1-R~4 are well documented, the parent molecule CH_2=SiH_2 (silene, silaethene. 1) still awaits unambiguous characterization in the gas phase, although convincing evidence for its formation as a transient has been deduced from trapping experiments. Moreover, IR and UV spectra of products isolated in an Ar matrix at 10 K and generated by vacuum flash pyrolysis of 5,6-bis(trifluoromethyl)-2-silabicyclo[2,2,2]-octa-5,7-diene (SBO) at 650°C and 1.4 X 10~(-5) mbar were attributed to 1. arid this conclusion was supported by ab initio calculations of the vibrationai waven umbers and by deuteration experiments. Furthermore, the first band observed and predicted at 8.95 eVin the He(I) photoelectron (PE) spectrum of 1 produced from SBO under similar conditions showed vibrationai fine structure that was consistent with the expected vibrationai energy pattern.