The reaction of trimethylsilyl radicals with nitric oxide, Si(CH3)3 + NO ↔ Si(CH3)3NO, has been studied using pulsed excimer-laser photolysis coupled with time-resolved photoionization mass spectrometry over the temperature range 300-812 K. The standard enthalpy of the reaction was obtained from the measured equilibrium constants using both second- and third-law methods. Ab initio calculations with empirical bond additivity corrections have been performed to determine the structure, vibrational frequencies, and energies of the low-lying electronic singlet and triplet states of the Si(CH3)3NO molecule. The calculated thermodynamic functions of the molecule were used to obtain the standard entropy of the reaction that was used in the third-law thermochemical calculations. The theoretical standard enthalpy of the reaction is in excellent agreement with that determined experimentally using the third-law procedure. The intrinsic Si(CH3)3-NO bond strength was determined using the measured enthalpy of the reaction at 298 K (by the third-law method) and the calculated relative enthalpy functions. This study provides the first direct experimental determination of a Si-N bond strength.
All Science Journal Classification (ASJC) codes
- Physical and Theoretical Chemistry