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

Abstract

The addition reactions of 16-electron complexes [(η6-arene)Ru(CabS,S′)] [3: arene = p-cymene (3a), C6Me6 (3b); CabS,S′ = 1,2-S2C2B10H10-S,S′] with the nucleophiles PEt3, CNBut, and CO lead to the formation of the corresponding 18-electron complexes 4-6 [(η6-arene)-Ru(CabS,S′)(L)] (L = PEt3, CNBut, 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(CabS,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.