物理化学学报
物理化學學報
물이화학학보
ACTA PHYSICO-CHIMICA SINICA
2011年
9期
2043-2050
,共8页
金催化剂%密度泛函理论%反应机理%[4+2]环化途径%[3+2]环化途径
金催化劑%密度汎函理論%反應機理%[4+2]環化途徑%[3+2]環化途徑
금최화제%밀도범함이론%반응궤리%[4+2]배화도경%[3+2]배화도경
Gold catalyst%Density functional theory%Reaction mechanism%[4+2] Benzannulation%[3+2] Benzannulation
对金属元素Au采用LanL2DZ基组,对非金属元素C,H,O,Cl采用6-31G*和6-311++G**基组,用密度泛函理论的B3LYP、B3PW91、UB3LYP方法和二阶微扰理论MP2方法研究了不同氧化态的金催化剂催化2-炔丙基苯酮与苯炔环化反应的机理.结果表明:在AuCl和AuCl3的作用下,反应均能通过[4+2]和[3+2]途径生成产物.但在AuCl催化下,[4+2]反应途径比[3+2]反应途径具有更低的活化自由能,反应主要通过[4+2]途径进行;而在AuCl3催化下,[4+2]反应途径与[3+2]反应途径的活化自由能相近,反应通过两条途径竞争生成产物.比较AuCl和AuCl3的催化效果发现,不同氧化态的金催化剂改变了反应的机理,该反应的活化自由能在AuCl作用下比在AuCl3作用下低11.18 kJ·mol-1.对于该反应,AuCl表现出了更好的催化活性.这些计算结果和实验现象相吻合.
對金屬元素Au採用LanL2DZ基組,對非金屬元素C,H,O,Cl採用6-31G*和6-311++G**基組,用密度汎函理論的B3LYP、B3PW91、UB3LYP方法和二階微擾理論MP2方法研究瞭不同氧化態的金催化劑催化2-炔丙基苯酮與苯炔環化反應的機理.結果錶明:在AuCl和AuCl3的作用下,反應均能通過[4+2]和[3+2]途徑生成產物.但在AuCl催化下,[4+2]反應途徑比[3+2]反應途徑具有更低的活化自由能,反應主要通過[4+2]途徑進行;而在AuCl3催化下,[4+2]反應途徑與[3+2]反應途徑的活化自由能相近,反應通過兩條途徑競爭生成產物.比較AuCl和AuCl3的催化效果髮現,不同氧化態的金催化劑改變瞭反應的機理,該反應的活化自由能在AuCl作用下比在AuCl3作用下低11.18 kJ·mol-1.對于該反應,AuCl錶現齣瞭更好的催化活性.這些計算結果和實驗現象相吻閤.
대금속원소Au채용LanL2DZ기조,대비금속원소C,H,O,Cl채용6-31G*화6-311++G**기조,용밀도범함이론적B3LYP、B3PW91、UB3LYP방법화이계미우이론MP2방법연구료불동양화태적금최화제최화2-결병기분동여분결배화반응적궤리.결과표명:재AuCl화AuCl3적작용하,반응균능통과[4+2]화[3+2]도경생성산물.단재AuCl최화하,[4+2]반응도경비[3+2]반응도경구유경저적활화자유능,반응주요통과[4+2]도경진행;이재AuCl3최화하,[4+2]반응도경여[3+2]반응도경적활화자유능상근,반응통과량조도경경쟁생성산물.비교AuCl화AuCl3적최화효과발현,불동양화태적금최화제개변료반응적궤리,해반응적활화자유능재AuCl작용하비재AuCl3작용하저11.18 kJ·mol-1.대우해반응,AuCl표현출료경호적최화활성.저사계산결과화실험현상상문합.
The AuClx (x=1,3)-catalyzed benzannulation mechanisms between benzyne and 2-propynylhypnone were investigated using B3LYP,B3PW91,UB3LYP,and the second-order Mφller-Plesset perturbation (MP2) methods with the LanL2DZ basis set for Au and the 6-31G*,6-311 ++G** basis sets for C,H,O,Cl.For the AuCl or AuCl3 catalysts the reaction occurs through both the [4 + 2] and the [3 + 2]benzannulation pathways to yield the product.With AuCl,the reaction occurs mainly through the [4 + 2]reaction pathway because of this pathway's low activation free energy.With AuCl3,the reaction occurs by the [4 + 2] and the [3 + 2] reaction pathways.These two pathways are competitive because of their close activation free energies.An analysis of these results indicates that the gold oxidation states change the reaction mechanisms and greatly influence the reaction barriers.The calculated results indicate that the AuCl catalyst is more effective than AuCl3 because in the reaction catalyzed by AuCl the activation free energy of the rate determining step is 11.18 kJ· mol-1 lower than that of the reaction catalyzed by AuCl3.These results are in good agreement with the experimental observations.
