Coordination ability of 1,10-phenanthroline-5,6-dione: syntheses and redox behavior of a Ru(II) complex with an o-quinoid moiety and of bridged Ru(II)-M(II) complexes (M = Pd, Pt)

The synthesis and electrochemical properties of a Ru(II) complex having a redox active ligand, 1,10-phenanthroline-5,6-dione, [Ru (trpy)(PD-N,Nʹ)Cl](PF6)([1](PF6)), and mixed-metal complexes [(PPh3)2Pd(O,Oʹ-PD-N,Nʹ)Ru(trpy)Cl](PF6)([2](PF6)) and [(PPh3)2Pt(O,OʹPD-N,Nʹ)Ru(trpy)Cl](PF6)([3](PF6))(trpy = 2,2ʹ:6ʹ,2"-terpyridine, PD = 1,10-phenanthroline-5,6-dione) are presented. The complex of [1] +, which was prepared by the reaction of Ru(trpy)(DMSO)Cl2 with PD in hot ethanol, underwent two reversible reductions in the PDbased redox reactions. The quinoid moiety of [1]+ was endowed with coordination ability to metals by one- and two-electron reduction of the complex. The mixed-metal complexes of [2]+ and [3]+ were synthesized by the reactions of [1]+ with M(PPh3)4(M = Pd, Pt), and both complexes have the [1]- and M(II) frameworks.