Aldehyde binding through reversible C-C coupling with the pincer ligand upon alcohol dehydrogenation by a PNP-ruthenium catalyst

Primary alcohol dehydrogenation by a PNP–Ru(II) catalyst was probed by low-temperature NMR experiments. Facile dehydrogenation occurred at −30 °C, but the resulting aldehydes were not found in solution, as they were trapped by the catalyst through a new mode of metal–ligand cooperation involving Ru–O coordination and an unusual, highly reversible C–C coupling with the PNP pincer ligand.