3. Exposure of 3, obtained together with dimers and remaining MA, to H, results in catalyst regeneration. Alternatively, a long-lived catalyst system can be operated under 1 atm of H2. While a IH signal at 6 1.6 for the Cp* ligand of the catalyst resting state could be observed,'the structure of this species, the mode of CC bond coupling, and details of the catalytic cycle were unknown. We report here low-temperature spectroscopic ...
