Synthesis and characterization of Pt(II) and Pt(II)/Ru(II) complexes with the bidentate bridging ligand dipyrido(2,3-a:3′,2′-h)phenazine (dpop)

Three new complexes [Pt(dpop)(Cl)2], [(Cl)2Pt(dpop)Pt(Cl)2] and [(bpy)2Ru(dpop)Pt(Cl)2](PF6)2 (dpop = dipyrido(2,3-a:3′,2′-h)phenazine) were prepared and studied. The electronic absorption spectra of the complexes display Pt dπ → dpop π* and Ru dπ → dpop π* MLCT transitions at longer wavelengths than for previously reported similar complexes. Results of cyclic voltammograms show reversible dpop centered reductions while for the mixed metal [(bpy)2Ru(dpop)Pt(Cl)2]2+ an irreversible Pt(II) oxidative wave precedes the Ru(II) oxidation/reduction couple. Spectroelectrochemical results show that all oxidative and reductive processes are completely reversible. The [(Cl)2Pt(dpop)Pt(Cl)2] complex cleaves in solution with pseudo-first order kinetics resulting in loss of the Pt dπ → dpop π* MLCT transition at 545 nm.