Zusammenfassung
Coordination of substitutionally inert [Ru(bpy)2]2+ fragments (bpy = 2,2'-bipyridine) to the a-iminoketone chelate ligands pyrazine-2-dimethylcarboxamide (L) and 4,7-phenanthroline-5,6-dione (HL') yields [Ru(bpy)2(L-N,O)]2+, [Ru(bpy)2(L'-O,O')]+, and ((L'-N,O;N',O')[Ru(bpy)2]24+ which exhibit a rich electrochem. The distinctly different electronic structures of the complexes are evident from the ESR behavior of paramagnetic intermediates: N,O-coordinated complexes have the unpaired electron residing in the ligand p system upon redn., albeit with g \textless2 for the complex of L but with g \textgreater2 for the binuclear complex of HL'. The paramagnetic O,O'-coordinated mononuclear complex with (L') has its redox potentials shifted pos. relative to that of the binuclear system. These results are particularly noteworthy because L and HL' can be regarded as model compds. for the flavin and methoxatin dehydrogenase cofactors. [on SciFinder(R)]
Nutzer
