Protonation of η5-indenyl ruthenium hydride complexes (η5-C9H7)Ru(L2)H and η5-η6 haptotropic rearrangement. X-ray crystal structures of (η5-C9H7)Ru(dppm)H and (η5-C9H8) Ru(dppp)H+

摘要

Protonation of indenyl complexes (η5-C9H7)Ru(dppm)H and (η5-C9H7)Ru(PPh3)2H with CF3-SO3H or HBF4·Et2O at -60°C gives the η2-dihydrogen complex [(η5-C9H7)Ru(dppm)(H2)]+ and the dihydrate [(η5-C9H7)Ru(PPh3)2H2]+, respectively. Upon warming to room temperature, proton shift from the η2-H2 ligand of the former to the indenyl ligand and subsequent migration of the metal fragment from the five-membered ring to the six-membered ring of the indene ligand results in the formation of the η6-indene complex [(η6-C9H8)Ru(dppm)H]+. The PPh3 analogue [(η6-C9H8)Ru(PPh3)2H]+ is formed in a similar fashion, but in this case, the proton shift is from Ru-H to the indenyl ligand. Low-temperature acidification of (η5-C9H7)Ru(dppe)H and (η5-C9H7)Ru (dppp)H yield mixtures of η2-dihydrogen complex and dihydride in both cases. Similar to the dppm and PPh3 analogues, η6-indene complexes [(η6-C9H8)Ru(dppe)H]+ and [(η6-C9H8)Ru(dppp)H]+ are generated upon warming solutions of the η2-dihydrogen complex/dihydride mixtures to room temperature. In the dppp system, the η5 → η6 haptotropic rearrangement only occurs after the η2-dihydrogen complex → dihydride tautomerization is nearly completed, whereas in the dppe system the two processes seem to occur simultaneously. The parent hydride complexes (η5-C9H7)Ru(L2)H can be regenerated upon deprotonation of the η6-indene complexes with Et3N. Crystal structures of (η5-C9H7)Ru(dppm)H and [(η6-C9H8)Ru(dppp)H]+ have been determined by X-ray crystallography; both complexes have three-legged piano-stool structures.