Acta Chimica Sinica ›› 2007, Vol. 65 ›› Issue (2): 129-134. Previous Articles     Next Articles

Original Articles

环丙酮光解离和热异构机理的从头算研究

艾玥洁, 林玲, 方维海*   

  1. (北京师范大学化学学院 北京 100875)
  • 收稿日期:2005-12-22 修回日期:2006-06-07 出版日期:2007-01-28 发布日期:2007-01-28
  • 通讯作者: 方维海

Ab initio Study on Mechanisms of Photodissociation and Thermal Isomerization of Cyclopropanone

AI Yue-Jie; LIN Ling; FANG Wei-Hai*   

  1. (College of Chemistry, Beijing Normal University, Beijing 100875)
  • Received:2005-12-22 Revised:2006-06-07 Online:2007-01-28 Published:2007-01-28
  • Contact: FANG Wei-Hai

In the present work, the potential energy profiles, governing the dissociation of cyclopropanone to CO+C2H4 in the S0, S1 and T1 states, have been determined using complete active space self-consistent field (CASSCF), density functional theory (DFT), and the second-order Moller-Plesset perturbation theory (MP2) in conjugation with the correlation-consistent atomic natural orbital basis set, cc-pVDZ. Upon photoexcitation in the range of 292~365 nm, the initial process was determined to be the α C—C bond cleavage after the cyclopropanone was excited to the S1 state. Our research found that the S1/S0 intersection point played an important role in the subsequent processes. On one hand, the singlet diradical is produced as an intermediate, which is followed by formation of CO and CH2=CH2 in the S0 state. On the other hand, the “hot” parent molecule can be formed through the S1/S0 intersection point, which has enough internal energies to overcome the barrier on the pathway to CO and CH2=CH2. Besides, the isomerization reactions of cyclopropanone in the ground state were investigated in this work.

Key words: cyclopropanone, ab initio calculation, photodissociation, isomerization, conical intersection