Compounds of the type [CpRu(PR3)2]2(μ-S2)[BF 4]2 were prepared via the unusual reaction of CpRu(PR3)2Cl, S8, and silver salts. Another route to these dimers includes the displacement of dihydrothiophene from [CpRu(PPh3)2(SC4H6)]+ with elemental sulfur. Optical and Raman spectroscopic studies of the dications indicate that their green colors (λmax = 718 nm) arise from transitions within the Ru2S2 core. Cyclic voltammetric measurements indicate that the dication can be oxidized (for the PMe3 derivative) and, in two well-separated steps, reduced. Salts of [CpRu(PPh3)2]2(μ-S2)+ were prepared via reduction of the dication with Et3N, benzyl alcohol, or thiophenol. The EPR spectrum of the monocation shows a five-line pattern indicating the equivalency of the four phosphorus centers. The structure of [CpRu(PMe3)2]2(μ-S2)[BF 4]2·2C6H5NO2 was determined by X-ray diffraction. The compound crystallized in the monoclinic space group P21/c with a = 8.424 (2) Å, b = 18.117 (5) Å, c = 17.424 (3) Å, and β = 92.13 (2)°. The structure was refined to a final R = 0.053 (Rw = 0.062). The dication is centrosymmetric with short Ru-S (2.208 (3) Å) and S-S (1.962 (4) Å) distances. The structure, electrochemistry, and stoichiometry of the dication indicate a delocalized, multiply bonded Ru..-S..-S..-Ru core.
ASJC Scopus subject areas
- Physical and Theoretical Chemistry
- Inorganic Chemistry