The syntheses and characterization of a series of binuclear iron(III) complexes of the chiral ligands N,N′-bis(2-pyridylmethyl)-(−) d 1,2-propanediamine, bispic(−)pn, C 15H 20N 4. N,N′-bis(2-pyridylmethyl)-(−) d -1,2-cyclohexanediamine, bispic(−)chxn, C 18H 24N 4, and N,N′-bis(2-pyridylmethyl)- N,N′-dimethyl-(−) dd -1,2-cyclohexanediamine, bispicMe 2(−)chxn, C 20H 28N 4, are described. The μ-oxoμ-carbonatodiiron(III,III) complex, [{Fe(bispicMe 2(−)chxn)} 2(μ-O)(μ-CO 3)](ClO 4) 2-4H 2O, [Fe 2C 41H 56N 8O 4](CIO 4) 2 · 4H 2O ( 1), crystallizes in the space group P2 12 12 1 of the orthorhombic system with four binuclear species in a cell of dimensions a = 14.066(3), b = 18.405 (4), c = 19.164(4) Å. The structure was refi ned to a final R-factor of 0.0941 based on 2045 observed independent reflections. The μ-oxo-μ-bicarbonatodiiron (III,III) complex, [{Fe(bispicMe 2(−)chxn)} 2(μ-O)(μ-HCO 3)][ClO 4) 3 · H 2O. [Fe 2C 41H 57N 8O 4](ClO 4) 3 · H 2O ( 2), crystallizes in the space group I4 122 of the tetragonal system with eight binuclear species in a cell of dimensions a = 20.527(3), c = 24.499(5) Å. The structure was refined to a final R-factor of 0.0527 based on 2604 observed independent reflections. The μ-oxu-μ acetatodiiron(III,III) complex, [{Fe(bispicMe 2(−)chxn)} 2(μ-O)(μ-OAc)](CIO 4) 3 · H 2O, [Fe 2C 42H 59N 8O 3] (ClO 4) 3 · H 2O ( 3), is isomorphous with 2 with eight binuclear species in a cell of dimensions a = 20.527(3), c = 24.377(5) Å. The structure was refined to a final R-factor of 0.0673 based on 1954 observed independent reflections. The complexes contain bent Fe-O Fe units with bridging Fe-O-Fe angles of 124.2(8), 130.7(4), and 130.6(6)° and associated Fe … Fe separations of 3.212(5), 3.283(2), and 3.287(5) A for 1, 2, and 3, respectively. The ligand binds the iron centers in cis- α fashion in all three complexes. The complexes exhibit electronic absorption bands similar to methemerythrin enzymes in the 400 to 550 nm region, but they do not exhibit negative circular dichroism spectral features like the enzymes. Cyclic voltammograms of the complexes reveal a reversible one-electron reduction, corresponding to the Fe IIIFe III→Fe IIFe III redox process, at −0.43, +0.08, and +0.12 V versus an Ag/AgCl reference electrode for 1, 2, and 3, respectively. Complexes 2 and 3 also exhibit an irreversible reduction peak at −0.86 and −0.83 V. respectively.