Monitoring of Reaction Intermediates in the Gas Phase: Ruthenium‑Catalyzed C–C Coupling

Investigation
of catalytic organometallic reactions often relies
on mass spectrometry. Frequently, however, possible reaction intermediates
along the catalytic cycle correspond to the same mass-to-charge ratio
and have rather similar molecular composition. We have shown for the
C–C coupling between phenylacetylene and pyridine catalyzed
by the ruthenium complex [RuCp­(PPh3)­(Py)2]+ that using a combination of collision-induced dissociation
experiments, infrared multiphoton dissociation spectroscopy, bimolecular
reactions, and DFT calculations it is possible to study isobaric complexes
and characterize the key intermediates in the reaction cycle. In addition,
a so far elusive ruthenium complex with π-coordinated alkyne
molecule has been spectroscopically characterized.

催化有机金属反应的研究通常依托质谱技术开展。然而，催化循环中的潜在反应中间体往往具有相同的质荷比，且分子组成高度相似。针对由钌配合物[RuCp(PPh3)(Py)2]+催化的苯乙炔与吡啶碳碳偶联反应，我们的研究证实，结合碰撞诱导解离（collision-induced dissociation）实验、红外多光子解离光谱（infrared multiphoton dissociation spectroscopy）、双分子反应实验以及密度泛函理论（DFT）计算，可对同重配合物进行研究，并完成反应循环中关键中间体的表征。此外，一种迄今尚未被探明的、带有π配位炔烃分子的钌配合物已通过光谱学手段完成表征。