Mixed-valent and radical states of complexes (bpy)2M(m-abpy)M'(bpy)2n+, M,M' = Ru or Os, abpy = 2,2'-azobispyridine: Electron transfer vs. hole transfer mechanism in azo ligand-bridged complexes. Inorganica Chimica Acta, (359)3:821--829, 2006. [PUMA: EPR azobispyridine bridge complex complex;electron complex;hole complex;mixed cyclic electrochem heterobinuclear;osmium homobinuclear osmium prepn redox ruthenium spectroelectrochem;radical transfer valence voltammetry]