The dynamics of reaction of Cl atoms with tetramethylsilane

Phys Chem Chem Phys. 2008 Mar 28;10(12):1675-80. doi: 10.1039/b716512a. Epub 2008 Feb 12.

Abstract

Rotational state distributions and state-selected CM-frame angular distributions were measured for HCl (v' = 0, j') products from the reaction of Cl-atoms with tetramethylsilane (TMS) under single collision conditions at a collision energy, E(coll), of 8.2 +/- 2.0 kcal mol(-1). The internal excitation of these products was very low with only 2% of the total energy available partitioned into HCl rotation. A transition state with a quasi-linear C-H-Cl moiety structure was computed and used to explain this finding. A backward peaking differential cross section was also reported together with a product translational energy (T') distribution with a maximum at T' approximately E(coll). This scattering behaviour is accounted for by reactions proceeding through a tight transition state on a highly skewed potential energy surface, which favours collisions at low impact parameters with a strong kinematic constraint on the internal excitation of the products. The large Arrhenius pre-exponential factor previously reported for this reaction is reconciled with the tight differential scattering observed in our study by considering the large size of the TMS molecule.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Algorithms
  • Anisotropy
  • Chlorine / chemistry*
  • Chlorine / radiation effects
  • Ethane / chemistry
  • Hydrochloric Acid / chemistry
  • Mass Spectrometry / methods
  • Models, Molecular
  • Photolysis
  • Trimethylsilyl Compounds / chemistry*

Substances

  • Trimethylsilyl Compounds
  • tetramethylsilane
  • Chlorine
  • Ethane
  • Hydrochloric Acid