Evidence for the powerful catalytic ability of imidozirconocene complex from its epoxide ring cleavage reactions - A DFT mechanistic view

Journal of Chemical Sciences

Rajadurai Vijay Solomon¹  Dhurairajan Senthilnathan¹  Ponnambalam Venuvanalingam1¹ 

[1]School of Chemistry, Bharathidasan University, Tiruchirappalli 620 024, India$$

关键词: Imidozirconocene complex;    epoxide ring cleavage reaction;    density functional theory;    AIM analysis.;   

DOI  :  

来源: Indian Academy of Sciences

【 摘 要 】

Imidozirconocene complex is known for its bifunctional reactivity and catalytic ability and this complex mediates ring cleavage of epoxides. Cyclooctene oxide (1) Norbornene oxide (2) and 2,5-dimethyl cyclohexene oxide (3) undergo ring cleavage in the presence of imidozirconocene complex. Epoxide 1 has accessible 𝛽-hydrogens (type I) while epoxide 2 and 3 do not have them (type II). Normally type I epoxides undergo elimination while type II epoxides prefer insertion. All the insertion reactions lead to five-membered metallacycle formation and elimination results in thermodynamically stable allyl-alkoxy product. The insertion is a two-step process following either diradical or zwitterionic pathway, while elimination is a one-step concerted reaction. DFT (density functional theory) modelling of these reactions at B3LYP/LANL2DZ level show that epoxide 1 undergoes elimination in agreement with experiment. However, calculations indicate that epoxide (2) proceeds through diradical intermediate in contrast to experimental observations. Surprisingly, epoxide (3) that has both the 𝛽 positions blocked by methyl groups undergoes elimination rather than insertion. AIM and EDA analyses offer further insights on the reaction mechanism and bifunctional reactivity of imidozirconozene complex.

【 授权许可】

Unknown