S–H Bond cleavage versus thiol co-ordination in half-sandwich ruthenium complexes†

Abstract

The complex [RuCp*Cl(dippe)] [dippe = 1,2-bis(diisopropylphosphino)ethane] underwent oxidative addition of H₂S in MeOH affording the ruthenium(IV) hydridothiol [RuCp*H(SH)(dippe)]⁺, which was isolated as its [BPh₄]^– salt 1. No oxidative addition has been observed in the course of the reaction of [RuCpCl(dippe)] with H₂S and NaBPh₄ in MeOH, and the binuclear disulfido derivative [{RuCp(dippe)}₂(µ-S₂)][BPh₄]₂ 2 was obtained. The related derivative [{RuCp*(dippe)}₂(µ-S₂)][BPh₄]₂ 3 was obtained by aerial oxidation of 1. At variance with this, the reaction of [RuCp*Cl(dippe)] and [RuCpCl(dippe)] with HSPh and NaBPh₄ in MeOH yielded respectively the ruthenium(III) thiolate complex [RuCp*(SPh)(dippe)][BPh₄] 4 and the extremely air-sensitive thiol adduct [RuCp(HSPh)(dippe)][BPh₄] 5. The latter is readily oxidized by atmospheric oxygen to the corresponding ruthenium(III) thiolate complex [RuCp(SPh)(dippe)][BPh₄] 6. The hydridometallothiol 1 as well as the thiolates 4 and 6 react with base affording respectively the neutral mercapto complex [RuCp*(SH)(dippe)] 7 and the neutral thiolate derivatives [RuCp*(SPh)(dippe)] 8 and [RuCp(SPh)(dippe)] 9. The reactivity of [RuCp*Cl(dippe)] and [RuCpCl(dippe)] towards pyridine-2-thiol and pyrimidine-2-thiol has also been examined.