The Design, Synthesis and Study of Mixed-Metal Ru,Rh and Os,Rh Complexes with Biologically Relevant Reactivit

A series of mixed-metal bimetallic complexes [(TL)2M(dpp)RhCl 2(TL')]3+ (M = Ru and Os, terminal ligands (TL) = phen, Ph2phen, Me2phen and bpy, terminal ligands (TL') = phen, bpy and Me2bpy ), which couple one Ru or Os polyazine light absorber (LA) to a cis-RhIIICl2 center through a dpp bridging ligand (BL), were synthesized using a building block method. These are related to previously studied trimetallic systems [{(TL)2M(dpp) 2RhCl2]5+, but the bimetallics are synthetically more complex to prepare due to the tendency of RhIII halide starting materials to react with diimine ligands to form cis-[Rh(NN) 2Cl2]+ motifs. The bimetallic complexes, [(phen) 2Ru(dpp)RhCl2(bpy)]3+, [(phen)2Ru(dpp)RhCl 2(phen)]3+, [(Ph2phen)2Ru(dpp)RhCl 2(phen)]3+, [(Me2phen)2Ru(dpp)RhCl 2(phen)]3+, [(bpy)2Ru(dpp)RhCl2(bpy)] 3+, [(bpy)2Ru(dpp)RhCl2(Me2bpy)] 3+ and [(bpy)2Os(dpp)RhCl2(phen)]3+, were characterized and studied by electrochemistry, electronic absorption spectroscopy, ESI-mass spectrometry, steady-state and time-resolved emission spectroscopy. (Abstract shortened by UMI.).