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

The reaction of alkylcobaloxime [Co(dmgH)(2)(CH2CH3)(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)(2)(CH2CH3)(SH)] (2). An H-1-H-1 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-2[Co-2(dmgH)(2)(CH2CH3)(2)(mu-S-3)]. 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.