Parent Cyclopentadienyl Ruthenium(II) Chloride Synthon: Derivatization to CpRu Amido, Imido, and Oxo Complexes

The complex salt [CpRu­(η6-C10H8)]­[(CpRu)2(μ-Cl)3] ([1]­[2]) was synthesized and found to be a useful CpRuCl synthon. The ions [1]+ and [2]− cleanly comproportionate into monomeric CpRuCl­(L)2 complexes with liberation of naphthalene upon treatment with donor ligands L such as DMSO, tBuNH2, 1,5-cycloctadiene, and CO. The amine adduct [CpRuCl­(NH2tBu)2] allows access to the coordinatively unsaturated dimeric amido complex [CpRu­(NHtBu)]2, which is subsequently transformed into the bridging imido complexes [(CpRu)2(μ-NtBu)­(μ-CH2)] and [(CpRu)2(μ-NtBu)­(μ-CH)]+. The imido methylidyne complex shows enhanced electrophilicity at the methylidyne carbon compared to its bulkier C5Me5 congener and also allows access to a less hindered parent Cp version of the diruthenocarbene ligand in the form of the Ru2Cu μ3-carbido complex [(CpRu)2(μ-NtBu)­(μ3-C)­Cu­{N­(SiMe3)2}]. The salt [1]­[2] also gives a novel tetranuclear μ4-oxo cluster [(CpRuCl)4(μ4-O)] upon oxidation in air or by N-methylmorpholine N-oxide.