Novel Structural Rearrangements Induced by Metal−Metal Interactions in Ruthenium(II) Ruthenocenyl- and (Pentamethylruthenocenyl)acetylide Complexes, RcC⋮CRuL₂(η⁵-C₅R₅) and Rc‘C⋮CRuL₂(η⁵-C₅R₅) [Rc = Ruthenocenyl, Rc‘ = Pentamethylruthenocenyl, L₂ = 2PPh₃ or Ph₂PCH₂CH₂PPh₂ (dppe), R = H or Me]

Abstract

The reaction of RcC⋮CH [Rc = (η 5 -C 5 H 5 )Ru(η 5 -C 5 H 4 )] with RuClL 2 (η 5 -C 5 R 5 ) [R = H or Me; L 2 = 2PPh 3 or Ph 2 PCH 2 CH 2 PPh 2 (dppe)] in the presence of NH 4 PF 6 and subsequent treatment with base gave Ru(II) ruthenocenylacetylide complexes RcC⋮CRuL 2 (η 5 -C 5 R 5 ) in good yields. In a similar manner, the pentamethylruthenocene analogues, Rc‘C⋮CRuL 2 (η 5 -C 5 R 5 ) [Rc‘ = (η 5 -C 5 Me 5 )Ru(η 5 -C 5 H 4 )], were also prepared. Cyclic voltammograms of the complexes showed two reversible one-electron-oxidation processes, consisting of the processes [Ru(II)Ru‘(II)] to [Ru(III)Ru‘(II)] and then to [Ru(III)Ru‘(III)]. Chemical oxidation of the complexes induced novel structural rearrangement. The two-electron oxidation of complex RcC⋮CRu(PPh 3 ) 2 (η 5 -C 5 H 5 ) afforded a kind of allenylidene complex, a cyclopentadienylidenethylidene complex, [(η 5 -C 5 H 5 )Ru{μ-η 6:η 1 -C 5 H 4 C C}Ru(PPh 3 ) 2 (η 5 -C 5 H 5 )] 2+, in 90% yield. The one-electron oxidation of Rc‘C⋮CRu(PPh 3 ) 2 (η 5 -C 5 H 5 ) gave the vinylidene complex (Rc‘CH C)Ru(PPh 3 ) 2 (η 5 -C 5 H 5 ) in 62% yield, while the two-electron oxidation led to the fulvene−vinylidene complex [(η 6 -C 5 Me 4 CH 2 )Ru{μ-η 5:η 1 -C 5 H 4 CH C}Ru(PPh 3 ) 2 (η 5 -C 5 R 5 )] 2+ by an intramolecular hydrogen transfer in 59% yield.