The syntheses and characterization of Os(II) and Ru(II)/Os(II) bimetallic complexes with dipyrido(2,3-a:3′,2′-j)phenazine (dpop′) and the bridging ligand 2,3,5,6-tetra(2-pyridyl)-pyrazine (tppz)

摘要

The syntheses of mixed ligand mono metallic [Os(dpop′)(tppz)](PF _6) _2, homo-bimetallic [(dpop′)Os(tppz)Os(dpop′)](PF _6) _4 and mixed metal bimetallic [(dpop′)Ru(tppz) Os(dpop′)](PF _6) _4 (dpop′ = dipyrido(2,3-a: 3′,2′-j)phenazine; tppz = 2,3,5,6-tetra(2-pyridyl)-pyrazine) complexes is described. NMR spectroscopy was used to confirm pure products were separated from similar species. The ~1H NMR spectrum for the mixed metal Ru/Os bimetallic complex ion reflects additive components of the Ru/Ru and Os/Os bimetallic species. Proton resonances on Ru(II) bonded ligands are upfield from Os(II) bonded ligands. Cyclic voltammetry for the Os/Os and Ru/Os bimetallic complex ions show the reversible tppz ~(0/-1) reduction at less negative potential than the dpop′ ~(0/-1) reduction. Additionally, the [(dpop′)Os(tppz)Os(dpop′)] ~(4+) ion displays reductive coupling of the remote terminal dpop′ ligands that is not observed in the bimetallic Ru/Ru species, indicating larger metal-ligand mixing occurs for Os(II) than Ru(II) complexes. The UV-Vis electronic absorption spectra for all complex ions show intense Os(dπ) → dpop′(π) and Os(dπ) → tppz(π) MLCT transitions in the visible spectrum with IL transitions in the UV.