The remarkable chemistry of mononuclear complexes featuring tridentate, meridionally chelating "pincer" ligands has stimulated the development of ligand frameworks containing multiple pincer sites. Here, the coordination chemistry of a novel pentadentate ligand (L-N3O2) that provides two closely spaced NNO pincer-type compartments fused together at a central diarylamido unit is described. The trianionic L-N3O2 chelate supports homobimetallic structures in which each M(II) ion (M = Co, Cu, Zn) is bound in a meridional fashion by the bridging diarylamido N atom and O,N-donors of the salicyaldimine arms. The metal centers are also coordinated by a mono- or bidentate auxiliary ligand (L-aux), resulting in complexes with the general form [M-2(L-N3O2)(L-aux)(2)](+) (where L-aux = 1-methyl-benzimidazole (1MeBI), 2,2'-bipyridine (bpy), 4,4'-dibromo-2,2'-bipyridine (bpy(Br2)), or (S)-2-(4-isopropyl-4,5-dihydrooxazolyl)pyridine (S-(iPr)OxPy)). The fused nature of the NNO pincer sites results in short metal-metal distances ranging from 2.70 angstrom for [Co-2(L-N3O2) (bpy)(2)](+) to 3.28 angstrom for [Zn-2(L-N3O2) (bpy)(2)](+), as revealed by X-ray crystallography. The complexes possess C-2 symmetry due to the twisting of the aryl rings of the mu-NAr2 core; spectroscopic studies indicate that chiral L-aux ligands, such as S-(iPr)OxPy, are capable of controlling the helical sense of the L-N3O2 scaffold. Since the four- or five-coordinate M(II) centers are linked solely by the amido moiety, each features an open coordination site in the intermetallic region, allowing for the possibility of metal-metal cooperativity in small-molecule activation. Indeed, the dicobalt(II) complex [Co-2(L-N3O2) (bpy(Br2))(2)](+) reacts with O-2 to yield a dicobalt(III) species with a mu-1,2-peroxo ligand. The bpy-containing complexes exhibit rich electrochemical properties due to multiple metal- and ligand-based redox events across a wide (3.0 V) potential window. Using electron paramagnetic resonance (EPR) spectroscopy and density functional theory (DFT), it was determined that one-electron oxidation of [Co-2(L-N3O2) (bpy)(2)](+) results in formation of a S = 1/2 species with a L-N3O2-based radical coupled to low-spin Co(II) centers.