New Acetylide Migration and Oxygen Transfer Reactions in Ruthenium Complexes Containing an Acetyl-Substituted Cp Ligand

Formation of [η5:η1-C5H4C(CH3)C(Ph)C(O)](PPh3)2Ru (3a) from the reaction of (η5-C5H4COCH3)(PPh3)2RuCl (2a) with PhC⋮CH proceeds via the vinylidene intermediate [(η5-C5H4COCH3)(PPh3)2RuCCHPh]Cl (4a). In this reaction the oxygen atom of the pendant acetyl group in the cyclopentadienyl ligand of 4a is transferred to Cα of the vinylidene ligand, and this transfer is accompanied by formation of a CC bond, giving 3a. Treatment of 2a with LiC⋮CPh affords (η5-C5H4C(CCPh)(OH)CH3)(PPh3)2RuCl (6a), and passing 6a through a column packed with alumina also gives 3a. The latter transformation involves a new migration of an acetylide group from exocyclic Cα of a substituted cyclopentadienyl ligand to the Ru center followed by the same oxygen transfer process. The metal acetylide (η5-C5H4COCH3)(BINAP)RuC⋮CPh (5c), resulting from the same migration but with no oxygen transfer, is isolated when two PPh3 ligands are replaced by BINAP. The structures of complexes 3a and 6b, a chirophos analogue of 6a, have been determined by...