Accessibility navigation


Time-resolved gas-phase kinetic, quantum chemical and RRKM studies of the reaction of silylene with 2,5-dihydrofuran

Becerra, R., Cannady, J. P., Pfrang, C. and Walsh, R. (2015) Time-resolved gas-phase kinetic, quantum chemical and RRKM studies of the reaction of silylene with 2,5-dihydrofuran. Journal of Physical Chemistry A, 119 (46). pp. 11241-11253. ISSN 1089-5639

[img]
Preview
Text - Accepted Version
· Please see our End User Agreement before downloading.

489kB
[img]
Preview
Text (Figures 4 & 5) - Accepted Version
· Please see our End User Agreement before downloading.

892kB
[img]
Preview
Text (Figure 6) - Accepted Version
· Please see our End User Agreement before downloading.

201kB

It is advisable to refer to the publisher's version if you intend to cite from this work. See Guidance on citing.

To link to this item DOI: 10.1021/acs.jpca.5b07404

Abstract/Summary

Time-resolved kinetic studies of silylene, SiH2, generated by laser flash photolysis of phenylsilane, have been carried out to obtain rate coefficients for its bimolecular reaction with 2,5-dihydrofuran (2,5-DHF). The reaction was studied in the gas phase over the pressure range 1-100 Torr in SF6 bath gas, at five temperatures in the range 296-598 K. The reaction showed pressure dependences characteristic of a third body assisted association. The second order rate coefficients obtained by RRKM-assisted extrapolation to the high pressure limits at each temperature, fitted the following Arrhenius equation where the error limits are single standard deviations: log(k/cm3 molecule-1 s-1) = (-9.96 ± 0.08) + (3.38 ± 0.62 kJ mol-1)/ RT ln10 End product analysis revealed no GC-identifiable product. Quantum chemical (ab initio) calculations indicate that reaction of SiH2 with 2,5-DHF can occur at both the double bond (to form a silirane) and the O-atom (to form a donor acceptor, zwitterionic complex) via barrierless processes. Further possible reaction steps have been explored, of which the only viable one appears to be decomposition of the O-complex to give 1,3-butadiene + silanone, although isomerisation of the silirane cannot be completely ruled out. The potential energy surface for SiH2 + 2,5-DHF is consistent with that of SiH2 with Me2O, and with that of SiH2 with cis-but-2-ene, the simplest reference reactions. RRKM calculations incorporating reaction at both π- and O-atom sites, can be made to fit the experimental rate coefficient pressure dependence curves at 296-476 K, giving values for k∞(π) and k∞(O) which indicate the latter is larger in magnitude at all temperatures, in contrast to values from individual model reactions. This unexpected result suggests that, in 2,5-DHF with its two different reaction sites, the O-atom exerts the more pronounced electrophilic attraction on the approaching silylene. Arrhenius parameters for the individual pathways have been obtained. The lack of a fit at 598K is consistent with decomposition of the O-complex to give 1,3-butadiene + silanone.

Item Type:Article
Refereed:Yes
Divisions:Interdisciplinary centres and themes > Walker Institute
Faculty of Life Sciences > School of Chemistry, Food and Pharmacy > Department of Chemistry
Interdisciplinary centres and themes > Chemical Analysis Facility (CAF) > Spectrometry (CAF)
ID Code:67271
Publisher:ACS Publications

Downloads

Downloads per month over past year

University Staff: Request a correction | Centaur Editors: Update this record

Page navigation