Kim, Yaewon, Chia-Hsiu Chen, and Christian Hilty. “Direct Observation of Ru-Alkylidene Forming into Ethylene in Ring-Closing Metathesis from Hyperpolarized 1H NMR.” Chemical Communications 54, no. 34 (2018): 4333–36.
https://doi.org/10.1039/C7CC08135A.
Ring-closing metathesis was monitored using real-time NMR of 1H hyperpolarized olefins at room temperature. By applying a selective saturation to an observable intermediate, its protons were found to transfer to ethylene. The intermediate was thus identified as a Ru-alkylidene species, which appears in the ethylene formation pathway.