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

Abstract

Formation of [η 5 :η 1 -C 5 H 4 C(CH 3 )dC(Ph)C(O)](PPh 3 ) 2 Ru (3a) from the reaction of (η 5 -C 5 H 4 -COCH 3 )(PPh 3 ) 2 RuCl (2a) with PhCtCH proceeds via the vinylidene intermediate [(η 5 -C 5 H 4 -COCH 3 )(PPh 3 ) 2 RudCdCHPh]Cl (4a). In this reaction the oxygen atom of the pendant acetyl group in the cyclopentadienyl ligand of 4a is transferred to C R of the vinylidene ligand, and this transfer is accompanied by formation of a CdC bond, giving 3a. Treatment of 2a with LiCtCPh affords (η 5 -C 5 H 4 C(CCPh)(OH)CH 3 )(PPh 3 ) 2 RuCl (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 C R of a substituted cyclopentadienyl ligand to the Ru center followed by the same oxygen transfer process. The metal acetylide (η 5 -C 5 H 4 COCH 3 )(BINAP)RuCtCPh (5c), resulting from the same migration but with no oxygen transfer, is isolated when two PPh 3 ligands are replaced by BINAP. The structures of complexes 3a and 6b, a chirophos analogue of 6a, have been determined by X-ray diffraction analysis.