Energetics of addition versus insertion mechanisms in the Si+(2P) + HCOOH reaction

✍ Scribed by A.I. González; M. Yáñez

• Publisher: Elsevier Science
• Year: 1996
• Tongue: English
• Weight: 504 KB
• Volume: 248
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(95)01316-4

✦ Synopsis

High-level ab initio calculations have been performed to investigate the preference of insertion processes with respect to the formation of adducts in the Si ++ formic acid reaction in the gas phase. We have found that the reactivity patterns shown by Si ÷ in reactions with methanol and formaldehyde are significantly different from those exhibited with formic acid, which has both functional groups. The most stable product of the reaction between Si ÷ and HCOOH corresponds to the insertion of the monocation into the C-OH bond of the neutral. Mostly importantly, the Si + association to the carbonyl oxygen atom is only 4.9 kcal/mol less favourable. All investigated local minima lie below the reactants in energy. In agreement with the experimental evidence, the formation of SiOH ÷ as a possible product of the Si++ HCOOH reaction is predicted to be exothermic by 41.7 kcal/mol. The distonic character of the products is discussed as well as the harmonic vibrational frequencies of the global minimum.