Time-resolved studies of the reactions of gas-phase dimethylsilylene

✍ Scribed by J.E. Baggott; M.A. Blitz; H.M. Frey; P.D. Lightfoot; R. Walsh

• Publisher: Elsevier Science
• Year: 1987
• Tongue: English
• Weight: 597 KB
• Volume: 135
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(87)87213-5

✦ Synopsis

We report rate constants for the reactions of SiMez with SiH,,, MeSiH,, Me2SiH2, Me,SiH, Me,Si and pentamethyldisilane obtained using laser flash photolysis/laser absorption techniques. ArF exciplex laser (193 nm) photolysis of pentamethyldisilane was used to generate SiMe2 radicals in the gas phase and the transient absorption of 457.9 nm radiation from an Ar+ laser was monitored in real time. Both time-resolved and end product analysis experiments are described, confirming that the transient species observed is the SiMez radical. When normalised for the number of Si-H bonds in the reactant molecules, the rate constants for SiMe2 + SiH+ MeSiHg, Me2SiH2 and Me$iH show a systematic increase with increasing methyl group substitution. We discuss possible explanations for this correlation. An improved estimate of A@ ( SiMe,, 298 K) = 26 f 2 kcal mol-' is obtained by combining these results with those from previous kinetic studies.