Gas-phase generation and photoelectron spectra of dimethyl- and diisopropylsilanethiones

The flash vacuum thermolysis of propargylthio- and allylthiodialkylsilanes, potential precursors of unhindered silanethiones (R2Si=S), 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 πsi-s double bond is energetically more stable than the earlier studied Si=N double bond.