Reaction of two dioxime ligands, viz. dimethylglyoxime (H2dmg) and diphenylglyoxime (H2dpg), (abbreviated in general as H2L, where H stands for the oxime protons) with [Ru(PPh3)3Cl2] in 1¦1 mole ratio affords complexes of type [Ru(PPh3)2(H2L)Cl2]. Structure of the [Ru(PPh3)2(H2dpg)Cl2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N2P2Cl2 with the two PPh3 ligands in trans and the two chlorides in cis positions. Reaction of the dioxime ligands with [Ru(PPh3)3Cl2] in 2¦1 mole ratio in the presence of a base affords complexes of type [Ru(PPh3)2(HL)2]. Structure of the [Ru(PPh3)2(Hdmg)2] complex has been solved by X-ray crystallography. The coordination sphere around ruthenium is N4P2 with the two PPh3 ligands in trans positions. Reaction of the [Ru(PPh3)2(H2dpg)Cl2] complex with a group of bidentate acidic ligands, viz. picolinic acid (Hpic), quinolin-8-ol (Hq) and 1-nitroso-2-naphthol (Hnn), (abbreviated in general as HL′, where H stands for the acidic proton) in the presence of a base affords complexes of type [Ru(PPh3)2(H2dpg)(L′)]+ isolated as perchlorate salts. All the complexes are diamagnetic (low-spin d6, S=0) and in dichloromethane solution show several intense MLCT transitions in the visible region. Cyclic voltammetry on all the complexes shows a reversible ruthenium(II)-ruthenium(III) oxidation within 0.36-0.98 V versus SCE followed by a quasi-reversible ruthenium(III)-ruthenium(IV) oxidation within 0.94-1.60 V versus SCE
