Spectroscopic, electrochemical and spectroelectrochemical investigations of mixed-metal osmium(II)/ruthenium(II) bimetallic complexes incorporating polypyridyl bridging ligands

Synthesized mixed-metal compounds of the general form ((bpy)2Os(BL)Ru(bpy)2)4+, where BL indicates the bridging ligands and dpp, dpb, and dpq indicate tpy, are studied for their spectroscopic electrochemical and spectroelectrochemical properties. A study of the electronic absorption spectra indicates a lowest energy transition Pi-Pi to the red on variation of the BL from dppt to dpq to apb. Spectroelectrochemistry confirms the assignment of the lowest energy transition levels with the first and second bimetallic complex reductions being attributed to the sequential bridging ligand reductions.