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)

Abstract

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,N′)Cl](PF₆) ([1](PF₆)), and mixed-metal complexes [(PPh₃)₂Pd(O,O′-PD-N,N′)Ru(trpy)Cl](PF₆) ([2](PF₆)) and [(PPh₃)₂Pt(O,O′-PD-N,N′)Ru(trpy)Cl](PF₆) ([3](PF₆)) (trpy = 2,2′:6′,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 PD-based 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.