Recently, the hydrophenoxylation of alkynes mediated by a gold catalyst has been shown to occur through a bimetallic process where the active species are [Au(OPh)(IPr)] and [Au(η²-alkyne)(IPr)]⁺. On the other hand, Cazin and co-workers have reported an improvement of the hydrophenoxylation reaction by using a combination of [Cu(OPh)(IPr)] and [Au(η²-alkyne)(IPr)]⁺. Herein, we performed DFT calculations to rationalize the performance of the Cu/Au bimetallic system. We have studied the rate determining step (rds) proposed by Poater et al. for the potential initial reagents PhO–[M] and alkyne–[M] species. Silver was also included in this study in order to understand the effect of the metal. Moreover, the effect of the steric hindrance on the rds was investigated with less sterically demanding ligands such as IMes, SIMes and IMe. Overall, the [Cu]/[Au] system was computed to be superior to the [Au]/[Au] system, but the [Ag]/[Au] couple exhibited the lowest energy barrier for the rds providing an enhancement of the heterometallic catalysis. We show that the rds is quite sensitive to the ligand steric hindrance.

中文翻译：

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金属在双苯乙炔的双金属催化加氢苯氧基化中的作用†

最近，由金催化剂介导的炔烃的hydrophenoxylation已经显示出通过双金属工艺，其中活性物质是[AU（OPH）（IPR）]和[AU（η发生² -alkyne）（IPR）] ⁺。在另一方面，察津和合作者已经通过使用[铜（OPH）（IPR）]和[金（η的组合报道的hydrophenoxylation反应的改进² -alkyne）（IPR）] ⁺。在这里，我们进行了DFT计算以合理化Cu / Au双金属系统的性能。我们研究了Poater等人提出的速率确定步骤（rds）。用于潜在的初始试剂PhO– [M]和炔烃[M]物种。为了理解金属的作用，本研究中还包括银。此外，使用对空间要求不高的配体（如IMes，SIMes和IMe）研究了位阻对rds的影响。总体而言，计算得出的[Cu] / [Au]系统优于[Au] / [Au]系统，但是[Ag] / [Au]对表现出最低的能垒，从而使rds增强。杂金属催化。我们表明，rds对配体的空间位阻非常敏感。