Quantum scattering study of the abstraction reaction of H atoms from tetramethylsilane

Atom Tunneling in Chemistry

“…Hydrogen atoms are frequently found to tunnel, even at room temperature,inclassical reactions of organic chemistry. In the case of reactions of closed-shell molecules with radicals, hydrogen is abstracted if the emerging radical is more stable than the previous one.V arious reactions of small organic molecules with hydrogen atoms, [153][154][155][156] hydroperoxyl radicals, [64] chlorine atoms, [157][158][159][160] or the activation of H 2 [161] have been studied experimentally as well as computationally. These reactions are influenced by tunneling,e ven at room temperature,t hereby raising the reaction rate constants.F or Claisen rearrangements it was necessary to computationally include am odel of tunneling through ap arabolic barrier to explain the experimental 13 CK IEs, [162][163][164] and in aS wern oxidation, multidimensional tunneling had to be included in computations to reproduce the experimental results.…”

Recent advances in quantum scattering calculations on polyatomic bimolecular reactions

“…In such an approach, the internal degrees of freedom (DoFs) of the system are divided into two groups: active modes and spectator modes. 253,254,[284][285][286][287][288][289][290][291][292] The PES is then constructed according to variations of the active mode coordinates, while the contribution of the spectator modes to the reaction are included as zero-point energies (ZPE). For instance, one commonly used 2D model 253, 254, 284-286, 288-290, 292 treats two bond lengths that correspond to the chemical bonds formed and broken in a reaction as the active modes.…”

“…For instance, one commonly used 2D model 253, 254, 284-286, 288-290, 292 treats two bond lengths that correspond to the chemical bonds formed and broken in a reaction as the active modes. Recently this method has been applied to larger systems, in particular the H-atom abstraction or exchange reactions, such as H+CH3NH2 → H2+CH3NH/CH2NH2 288 , H+CH4 → H2+CH3 284,285 , CH3+CH4 → CH4+CH3 285,286 , Cl+CH4/CHD3 → HCl+CH3/CD3 253,254 , H+C2H6 → H2+C2H5 287 , H+C3H8 → H2+n-C3H7/i-C3H7 287 , H+n-C4H10 → H2+1-C4H9/2-C4H9 291 , H+HCF3 → H2+CF3 293 , H+cyc-C3H6 → H2+cyc-C3H5 292 , H+Si(CH3)4 → H2+Si(CH3)3CH2 289 , H+H2CO → H2+HCO 290 , and Cl − +CH3Br → Br − +CH3Cl 294 .…”

“…283,295 The resulting rate constants had very good agreement to the experimental data and also showed clear contribution of the quantum tunneling effect to the reaction. A similar procedure has been recently applied to the study of H+H2CO → H2+HCO 290 and H+Si(CH3)4 → H2+Si(CH3)3CH2 289 reactions.…”

Der Tunneleffekt von Atomen in der Chemie

“…Im Fall von Reaktionen geschlossenschaliger Moleküle mit Radikalen wird Wasserstoff abstrahiert, wenn das entstehende Radikal stabiler ist als das vorherige. Verschiedene Reaktionen von kleinen organischen Molekülen mit Wasserstoffatomen, Hydroperoxidradikalen, Chloratomen oder die Aktivierung von H 2 wurden experimentell und mit theoretischen Methoden untersucht. Auch bei Raumtemperatur werden diese Reaktionen vom Tunneleffekt beeinflusst, was zu erhöhten Reaktionsgeschwindigkeitskonstanten führt.…”