A Mechanistic Study of the Utilization of
<i>arachno</i>
‐Diruthenaborane [(Cp*RuCO)
<sub>2</sub>
B
<sub>2</sub>
H
<sub>6</sub>
] as an Active Alkyne‐Cyclotrimerization Catalyst
作者:K. Geetharani、Samat Tussupbayev、Julia Borowka、Max C. Holthausen、Sundargopal Ghosh
DOI:10.1002/chem.201200291
日期:2012.7.2
conditions yields the new metallaborane arachno‐[(Cp*RuCO)2B2H6] (2). Compound 2 catalyzes the cyclotrimerization of a variety of internal‐ and terminal alkynes to yield mixtures of 1,3,5‐ and 1,2,4‐substituted benzenes. The reactivities of nido‐1 a and arachno‐2 with alkynes demonstrates that a change in geometry from nido to arachno drives a change in the reaction from alkyne‐insertion to catalytic
的反应巢- [1,2-(CP *期RuH)2乙3 ħ 7 ](1一个中,Cp * =η 5 -C 5我5)与[沫(CO)3(CH 3 CN)3 ]在温和条件下产生新的金属laborane arachno -[(Cp * RuCO)2 B 2 H 6 ](2)。化合物2催化多种内部和末端炔烃的环三聚反应,生成1,3,5-和1,2,4-取代的苯的混合物。Nido - 1a和Nido的反应性带有炔烃的arachno - 2证明,几何形状从Nido变为Arachno分别驱动了从炔烃插入到催化环三聚反应的变化。密度泛函计算已用于评估化合物2催化的炔烃环三聚反应的反应途径。该反应涉及钌环中间体的形成,随后的炔烃插入步骤是由该中间体与炔烃之间的[2 + 2]环加成反应引发的。实验和量子化学结果还表明,金属环中间体的稳定性在很大程度上取决于炔烃上存在的取代基的性质。