Reactivities and structural and electrochemical studies of coordinatively unsaturated arene(dithiolato)Ru(II) complexes

The addition reactions of 16-electron complexes [(η⁶-arene)Ru(Cab^S,S′)] [3: arene = p-cymene (3a), C₆Me₆ (3b); Cab^S,S′ = 1,2-S₂C₂B₁₀H₁₀-S,S′] with the nucleophiles PEt₃, CNBu^t, and CO lead to the formation of the corresponding 18-electron complexes 4-6 [(η⁶-arene)-Ru(Cab^S,S′)(L)] (L = PEt₃, CNBu^t, CO), which have been characterized by X-ray crystallography. Investigation of the redox process in a series of these base-adduct metalladithiolene complexes by cyclic voltammetry reveals a large dependence of the redox potentials on the nature of the ancillary η⁶-arene and incoming L ligand. In an analogous manner, the reactivity of 3a toward arylamines (7) has been found to produce [(η⁶-p-cymene)Ru(Cab^S,S′)-(L)] (8) [L = η¹-NH₂(CH₂CH₂)Ar, Ar = C₆H₅ (8a); C₆H₄OMe (8b); C₆H₃(OMe)₂ (8c); C₈H₆N (8d)], having molecular structures closely related to those of 4 and 5, as deduced by an electrochemical analysis and NMR studies. In addition, complex 3 reacts with a variety of substrates such as alkynes and a diazoalkane, generating a new class of dithiolato ruthenium-(II) complexes incorporating alkene and alkylidene units. Thus, the syntheses of the half-sandwich ruthenium(II) complexes [(η⁶-arene)Ru{η³-(S,S,C′)-SC₂B ₁₀H₁₀SC′R₂}] [C′R₂ = (COOMe)C=C(COOMe) (9: arene = p-cymene (9a), C₆Me₆ (9b)), HC=CPh (10: arene = C₆Me₆ (10b)), CH₂SiMe₃ (11: arene = p-cymene (11a), C₆Me₆ (11b))] are reported, and the structure of lib has been established by an X-ray diffraction study. The formation of 9 and 10 has also been electrochemically investigated.