PHOTOCHEMISTRY OF SILICON-COMPOUNDS .6. 147-NM PHOTOLYSIS OF TETRAMETHYLSILANE

The 147-nm gas-phase photolysis of tetramethylsilane yielded ten measurable and several trace products along with a solid deposit. From the effect of pressure, exposure time, deuterium labeling, and added nitric oxide on the quantum yields of individual products, the following primary steps were postulated: CH3 + Si(CH3)3 (φ = 0.43); 2CH3 + Si(CH3)2 (φ = 0.24); CH4 + CH2Si(CH3)2 (φ = 0.17); CH3 + H + CH2Si(CH3)2 (φ = 0.10); H2 + CHSi(CH3)3 (φ = 0.02); and CH2 + (CH3)3SiH (φ = 0.04). Fluorescence could not be observed and the upper limit for φf is 10-5. The secondary reactions of the principal silicon radicals Si(CH3)3, CH2Si(CH3)2, and Si(CH3)2 and the mechanism of the nitric oxide inhibited reaction are discussed and it is shown that the siloxy radical (CH3)3SiO can displace CH3 from the substrate to give hexamethyldisiloxane. © 1979 American Chemical Society.