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首页> 外文期刊>Organometallics >Density functional study of Mo-carbonyl-catalyzed alkynol cycloisomerization: Comparison with W-catalyzed reaction
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Density functional study of Mo-carbonyl-catalyzed alkynol cycloisomerization: Comparison with W-catalyzed reaction

机译：Mo-羰基催化炔醇环异构化的密度泛函研究：与W催化反应的比较

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Mo-catalyzed endo-cycloisomerizations of alkynes tethered to alcohols have been studied using density functional theory, and comparisons were made with the W-catalyzed reaction. The cycloisomerization is initiated with the formation of metal alkyne pi complex and is followed by the rate-determining step, which transforms the pi complex to a vinylidene carbene complex, considered to be critical for endo-mode cyclization. Several different alkynols have been selected to investigate five- and six-membered ring endo-cycloisomerizations in the presence of Mo(CO)(5) catalyst. The energy barriers calculated for five- and six-membered ring cycloisomerizations are within a range of 25-30 kcal/mol for most cases studied, showing no significant energy difference between the two metals. The stabilization effect of THF and Et3N solvents and the substitution reaction of THF by alkynol substrates in the reaction process with Mo and W complexes are studied as well. The principal difference between Mo- and W-catalyzed cycloisomerization processes appears to be the initial formation of a pi complex, which is more stabilizing for formation of the W-alkyne vs Mo-alkyne complexes.
机译：利用密度泛函理论研究了Mo催化的炔烃与醇的内环异构化反应，并与W催化的反应进行了比较。环异构化是通过形成金属炔pi复合物而开始的，然后是速率确定步骤，该步骤将pi复合物转化为对内模环化至关重要的亚乙烯基卡宾复合物。已经选择了几种不同的炔醇来研究在Mo（CO）（5）催化剂存在下的五元和六元环内环异构化反应。在大多数研究情况下，五元和六元环环异构化的能垒在25-30 kcal / mol的范围内，表明两种金属之间没有明显的能量差。还研究了THF和Et3N溶剂的稳定作用以及在Mo和W配合物反应过程中THF被炔醇底物取代的反应。 Mo和W催化的环异构化过程之间的主要区别似乎是pi配合物的初始形成，它对于W炔与Mo炔配合物的形成更稳定。

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