A gas-phase kinetic study of the silylene addition reaction SiH₂ + C₂D₄as a function of temperature and pressure: isotope effects and mechanistic complexities

Time-resolved gas-phase kinetic study of the germylene addition reaction, GeH2 + C2D4, as a function of temperature and pressure: isotope effects and mechanistic complexities

“…The kinetic isotope effects, k D /k H , are also listed. It is clear that the rate constants decrease with temperature (just as has been found for the analogous SiH 2 additions to C 2 H 4 21 and C 2 D 4 25 ). It is also clear that k D is significantly greater than k H and that k D /k H values increase with decreasing temperature.…”

“…Rice, Ramsperger, Kassel, Marcus (RRKM) theoretical modelling studies of these pressure dependencies have shown them to be consistent with the formation of silirane and silirene rings and the experimental results have yielded information about the strain energies of these rings. Isotopic labelling studies 18,19,24,25 have revealed the presence of scrambling mechanisms consistent with facile and reversible ring opening reactions of siliranes and silirenes leading to formation of isomeric alkyl-and alkenyl-silylenes, as suggested by earlier product analytical studies, [26][27][28][29][30][31] and supported by theoretical calculations. [32][33][34][35] We have recently studied the kinetics of GeH 2 + C 2 H 4 13 and GeH 2 + C 3 H 6 11 and shown that they are broadly consistent with formation of germirane products.…”

“…Such abnormal isotope effects have already been observed in studies of SiH 2 with C 2 D 2 23,24 and SiH 2 + C 2 D 4 . 18,19,25 There has been no previous kinetic study of the reaction of GeH 2 with C 2 D 4 .…”

Gas phase kinetic and theoretical studies of reactions of germylenes and dimethylstannylene

“…89 This explains why the reaction GeH 2 + C 2 D 4 does not show any pressure dependence, while for SiH 2 + C 2 D 4 a small effect is observed. 77 Be cause of the endothermicity of the isomerization of silirane to ethylsilylene, the efficiency of the scrambling process is lesser in this case than in the case of the exothermic rearrangement of germirane to ethylgermylene. As has been discussed above, the occurrence of this isomeriza tion of silirane to ethylsilylene was experimentally dem onstrated by observed isotope exchange during the reac tion of SiH 2 with C 2 D 4 .…”

Computational study of 2-vinylsilirane to silacyclopent-3-ene rearrangement

“…This pathway has been studied for parent silirane theoretically [16,23] and experimentally [24] (for discussion of H-transfer reactions in siliranes and 2-vinylsiliranes see also [25]). Comprehensive quantum chemical study of the H-transfer reactions in the C 4 H 6 -SiH 2 system will be published separately.…”