Organometallic sulfur complexes: Reactivity of the hydrogen sulfide anion with cobaloximes

The reaction of alkylcobaloxime [Co(dmgH)<inf>2</inf>(CH<inf>2</inf>CH<inf>3</inf>)(py)] (1) (dmgH = the anion of dimethyl-glyoxime) with KSH in water solution resulted in the selective displacement of the pyridine axial ligand affording the derivative K[Co(dmgH)<inf>2</inf>(CH<inf>2</inf>CH<inf>3</inf>)(SH)] (2). An ¹H-¹H EXSY experiment revealed that the substitution is reversible and occurs in a slow exchange regime. Attempts to grow crystals of the HS^- adduct led to isolation of a rare example of the unexpected trisulfido-bridged dinuclear complex K<inf>2</inf>[Co<inf>2</inf>(dmgH)<inf>2</inf>(CH<inf>2</inf>CH<inf>3</inf>)<inf>2</inf>(μ-S<inf>3</inf>)]. It was shown that the glyoximato ligands provided the metal centre with a coordination environment quite robust to prevent decomposition and constitute a suitable platform for developing the chemistry of organometallic complexes bearing hydrogensulfido or oligosulfido ligands.