Chemistry of some ruthenium phenolates: synthesis, characterization and redox properties

Reaction of phenols containing a second donor site linked to the ortho-position [viz 2,4,6-tribromophenol (HL1), 2-nitrophenol (HL2) and 2,4,6-trinitrophenol (HL3)] with [Ru(bpy)2Cl2] in the presence of a base has afforded complexes of the type [Ru(bpy)2(L)]+ (where L stands for the deprotonated ligands), which have been isolated as perchlorate salts in the solid state. The complexes are diamagnetic (low-spin d6, S=0) and in solution show several MLCT transitions in the visible region. Cyclic voltammetry of the [Ru(bpy)2(L)]+ complexes in acetonitrile solution (0.1 M TEAP) shows a RuII-RuIII oxidation within 0.63 to 0.93 V vs SCE and one reduction of the coordinated bpy within -1.42 to -1.68 V vs SCE. (author)