Rate constants for the gas-phase reactions of silylene with methanol, deuterated methanol, and water

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dc.contributor.authorAlexander, U.
dc.contributor.authorKing, K.
dc.contributor.authorLawrance, W.
dc.date.issued2002
dc.description.abstractGas-phase reaction rate constants for the reaction of silylene, SiH2, with deuterated methanol, CD3OD, have been determined over the temperature range 294-423 K and at total pressures over the range 100-800 Torr of the inert bath gas, Ar. Rate constants have also been measured for the reaction of SiH2 with CH3OH at 294 K over the range 100-800 Torr, also with Ar. Rate constants for the reaction of SiH2 with H2O over the range 50-200 Torr in Ar have been determined at 294 K. The second-order rate constants are pressure-dependent up to the maximum pressures investigated. For CD3OD, for which temperature-dependent data have been obtained, the rate constants decrease with increasing temperature, indicating that the reaction proceeds via the formation of a complex. At the highest temperature studied (423 K), the experimental decay curves indicate the system approaching equilibrium, providing direct experimental evidence for the formation of the complex. Analysis of the 423 K decay curves provides an experimental determination of the equilibrium constant, Keq, and a value for the dissociation energy of the complex of 83.0 ± 1.3 kJ mol-1. The Rice-Ramsperger-Kassel-Marcus (RRKM)/master equation modeling gives a dissociation energy for the SiH2-CD3OD complex of 83.7 kJ mol-1. Ab initio calculations, performed at the MP2/6-311+G** level of theory, give a value of 75.4 kJ mol-1, in reasonable agreement with this value. The RRKM/master equation modeling for SiH2 + CD3OD, when adjusted to account for the changes arising from deuteration, reproduces the behavior observed for SiH2 + CH3OH. The high-pressure limit predictions of the RRKM/master equation modeling are quite unusual and may indicate unusual pressure and temperature behavior in weakly bonded systems.
dc.description.statementofresponsibilityUla N. Alexander, Keith D. King and Warren D. Lawrance
dc.identifier.citationJournal of Physical Chemistry A, 2002; 106(6):973-981
dc.identifier.doi10.1021/jp012773v
dc.identifier.issn1089-5639
dc.identifier.issn1520-5215
dc.identifier.orcidKing, K. [0000-0003-2766-2330]
dc.identifier.urihttp://hdl.handle.net/2440/877
dc.language.isoen
dc.publisherAmer Chemical Soc
dc.source.urihttps://doi.org/10.1021/jp012773v
dc.titleRate constants for the gas-phase reactions of silylene with methanol, deuterated methanol, and water
dc.typeJournal article
pubs.publication-statusPublished

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