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The decomposition kinetics of chemically activated methyl‐ d 1 ‐methylsilane‐ d 2 and ethylsilane‐ d 3
Author(s) -
Richardson T. H.,
Simons J. W.
Publication year - 1978
Publication title -
international journal of chemical kinetics
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.341
H-Index - 68
eISSN - 1097-4601
pISSN - 0538-8066
DOI - 10.1002/kin.550101005
Subject(s) - chemistry , reaction rate constant , rrkm theory , kinetics , decomposition , kinetic isotope effect , activation energy , chemical kinetics , computational chemistry , thermodynamics , organic chemistry , deuterium , atomic physics , physics , quantum mechanics
The decomposition kinetics of chemically activated methyl‐ d 1 ‐methylsilane‐ d 2 (DMS‐ d 3 * ) and ethylsilane‐ d 3 (ES‐ d 3 * ) from the Si‐D and C‐H insertion reactions of CH 2 ( 1 A 1 ) with methylsilane‐ d 3 have been studied. The total rate constants for decomposition of chemically activated DMS‐ d 3 and ES‐ d 3 have been measured. The individual rate constants for molecular elimination of CH 3 D, CH 2 D 2 , and D 2 from DMS‐ d 3 *and for molecular elimination of CH 3 CH 2 D and D 2 from ES‐ d 3 *have been measured. All of the above rate constants exhibit the expected kinetic isotope effect when compared to those found previously in the undeuterated system. RRKM theory calculations of the rate constants for the expected C‐Si and Si‐D bond rupture processes, based on energetics and activated comple× models deduced previously for the undeuterated system, were carried out. In the case of DMS‐ d 3 *the RRKM theory calculations of rate constants for the bond rupture processes combined with experimental rate constants for the molecular elimination processes gave a total rate constant for decomposition in agreement with the measured value. The results of a high‐pressure study of the CH 3 D/CH 2 D 2 ratio from chemically activated DMS‐ d 3 decomposition were consistent with complete randomization of internal energy up to a pressure of 4 atmospheres (lifetime of ∼1.7 × 10 ×11 sec). This is not an unexpected result in light of earlier work.