Kinetics of the gas-phase reaction between iodine and monosilane and the bond dissociation energy D(H3SiH)

✍ Scribed by Alan M. Doncaster; Robin Walsh

• Publisher: John Wiley and Sons
• Year: 1981
• Tongue: English
• Weight: 546 KB
• Volume: 13
• Category: Article
• ISSN: 0538-8066
• DOI: 10.1002/kin.550130508

✦ Synopsis

The title reaction has been investigated in the temperature range of 494-545 K. During the early stages of reaction the only observed products were silyl iodide and hydrogen iodide. Initial rates were found to obey the rate law

over a wide range of initial iodine and monosilane pressures. Secondary reactions, most probably of SiHSI with 12, became more important as the reaction progressed. However, provided [SiH&/[I&, > 20, these secondary processes had a negligible effect on the kinetics, and an integrated rate expression could be used. These kinetics are consistent with an iodine atom abstraction chain mechanism, and for the step 1 I + SiH4 + SiH3 + HI log kl(dm3/mol sec) = (12.04 f 0.19) -(87.8 f 1.9 kJ/mol)/RT In 10 has been deduced. From this the bond dissociation energy D(SiH3-H) = 378 f 5 kd/mol (90 kcal/mol) is obtained. The kinetic and thermochemical implications of this value, especially to the pyrolysis of monosilane, are discussed.