Acta Phys. -Chim. Sin. ›› 1999, Vol. 15 ›› Issue (01): 35-39.doi: 10.3866/PKU.WHXB19990107

• ARTICLE • Previous Articles     Next Articles

Theoretical Studies on the Mechanism of Dimerization Reactions of Thioketene

Wang Yan, Fang De-Cai, Fu Xiao-Yuan   

  1. Department of Chemistry,Beijing Normal University,Beijing 100875
  • Received:1998-04-14 Revised:1998-06-18 Published:1999-01-15
  • Contact: Fu Xiao-Yuan

Abstract:

 Dimerization reactions of thioketene and bis(trifluoromethyl) thioketene have been studied by means of HF/6-31G* and semiempirical AMI. All the geometries of the stationary points on the reactions path have been optimized by energy gradient technique, and all the transition states were characterized by vibration frequency analysis. The results can be summed up as follows: three different dimerization processes of thioketene and bis(trifluoromethyl)thioketene are all concerted but nonsynchronous,taking place through twisted four-membered cyclic transition states. The activation enthalpies were calculated to be 122.53, 126.47 and 136.68 kJ•mol-1 respectively for three thioketene dimerization processes. Contrarily, for the three bis(trifluoromethyl)thioketene dimerization reactions, the activation enthalpies are 287.05,274.65 and 218.84kJ•mol-1 respectively, which are in consistence with experimental fact.

Key words: Thioketene, Bis(trifluoromethy)thioketene, Dimerization, Reaction mechanism