Visible Light-Activated CO Release and O Photosensitizer Formation with Ru(II),Mn(I) Complexes.

Two diimine-bridged Ru(II),Mn(I) complexes with a [(bpy)Ru(BL)Mn(CO)Br] architecture, where bpy = 2,2'-bipyridine and BL = 2,3-bis(2-pyridyl)pyrazine (dpp; Ru(dpp)Mn) or 2,2'-bipyrimidine (bpm; Ru(bpm)Mn), were designed to both dissociate multiple equivalents of CO and produce O when irradiated with visible light. Analysis of the complexes by Fourier transform infrared (FTIR) spectroscopy and cyclic voltammetry suggest a stronger π-accepting ability for bpm compared to that of dpp. Both complexes absorb light throughout the UV and visible regions with lowest energy absorption bands comprising overlapping Ru(dπ)→BL(π*) and Mn(dπ)→BL(π*) singlet metal-to-ligand charge transfer (MLCT) and Br(p)→dpp(π*) singlet halide-to-ligand charge transfer (XLCT) transitions.