Gas-Phase Generation and Photoelectron Spectra of Dimethyl- and Diisopropylsilanethiones1

The flash vacuum thermolysis of propargylthio- and allylthiodialkylsilanes, potential precursors of unhindered silanethiones (R2SiS), has been investigated by photoelectron spectroscopy. This technique allowed us to characterize in the gas phase two very reactive species of this series, dimethyl- and diisopropylsilanethione. According to the values observed for the ionization potentials associated with the ejection of a π electron, the πSiS double bond is energetically more stable than the earlier studied SiN double bond.