Theoretical analyses of hydrogen abstraction by aldehyde triplet excited states

✍ Scribed by D. Severance; H. Morrison

• Publisher: Elsevier Science
• Year: 1989
• Tongue: English
• Weight: 312 KB
• Volume: 163
• Category: Article
• ISSN: 0009-2614
• DOI: 10.1016/0009-2614(89)85184-x

✦ Synopsis

The fully optimized transition states for hydrogen abstraction from methane by formaldehyde and acetaldehyde have been computed using UMP2/6-31G(d)//6-31G(d) calculations. The geometry of the formaldehyde/methane transition state matches well with the geometry obtained previously using the 3-21G basis set, but the energy is lowered somewhat ( IX.7 versus 22 kcal/ mol, respectively). Approach of the methane trans-penplanar (i.e. anti) to the acetaldehyde methyl group leads to a transition state similar to that for formaldehyde (saddle point at 17.9 kcal/mol). Approach syn to the methyl group leads to a modest variation in both the saddle point geometry and energy ( 19.1 kcal/mol), both attributed to unfavorable steric interactions in this trajectory.