锗苯与腈氧化物1,3偶极环加成反应理论研究

采用密度泛函理论(DFT)方法在B3LYP/6-311G**水平研究了锗苯与腈氧化物的1,3偶极环加成反应的微观机理、势能剖面,考察取代基和四氢呋喃溶剂对反应势能剖面的影响.计算结果表明,所研究反应均以协同但非同步的方式进行,且总是Ge—O键先于C—C键形成.锗苯分子中Ge原子上的给电子和吸电子取代基均有利于反应的进行,而腈氧化物C原子上的2,4,6-三甲苯基取代基在热力学上对反应很不利.四氢呋喃溶剂对所研究反应的势能剖面影响不大.

Theoretical studies on the 1,3-dipolar cycloaddition reactions between germabenzenes and nitrile oxides

The mechanism and potential energy surface of 1,3-dipolar cycloaddition reactions between germabenzenes and nitrile oxides were investigated using density functional theory(DFT) calculations at the B3LYP/6-311G(d,p) level.The influences of substituents and tetrahydrofuran as a solvent on the potential energy surface of reactions were explored.The results show that all of the studied reactions proceed via a concerted but asynchronous way and the formation of Ge—O bond always keep ahead the formation of C—C bond.Both electron-donating and electron-withdrawing substituents at Ge atom of germabenzene molecule favor the 1,3-dipolar cycloaddition reactions,while mesityl substituent at C atom of nitrile oxide have opposite effects thermodyndmically.The influence of tetrahydrofuran solvent on the potential energy surface of the studied reactions is not large.