Iron complexes of the Fe-III(N-N)(DBSQ)(DBCat) series, where N-N = bpy, tmeda, and DBSQ and DBCat are semiquinonate and catecholate ligands derived from 3,5- and 3,6-di-teut-butyl-1,2-benzoquinone, have been investigated to assess the potential for isomerism to Fe-II(N-N)(DBSQ)(2) species in the manner of related complexes of Mn and Co. Crystallographic characterization is provided for Fe(bpy)(3,6-DBSQ)(3,6-DBCat) [monoclinic, C2/c, a = 10.809(1) Angstrom, b = 30.149(6) Angstrom, c = 12.275(2) Angstrom, beta = 114.52(1)degrees, and Z = 4], Fe(tmeda)(3,6-DBSQ)-(3,6-DBCat) [monoclinic, P2(1)/c, a = 14.531(3) Angstrom, b = 13.328(3) Angstrom, c = 19.781(3) Angstrom, beta = 106.63(2)degrees, and Z = 4], and Fe(tmeda)(3,5-DBSQ)(3,5-DBCat). 2C(3)H(5)OH [monoclinic, P2(1)/n, a = 11.884(2) Angstrom, b = 14.856(2) Angstrom, c = 25.115(5) Angstrom, beta = 93.15(2)degrees, and Z = 4]. All three complex molecules are monomeric and octahedral. Intermolecular stacking for Fe(bpy)(3,6-DBSQ)(3,6-DBCat) appears responsible for an anomalous drop in magnetic moment at low temperature; the complexes containing tmeda ligands have S = 2 magnetic moments that result from strong Fe(III)-semiquinone radical antiferromagnetic exchange. Electronic spectra of all three complexes show strong solvatochromic effects, little temperature dependence, and no bands in the infrared that appear characteristically for related Co(III) and Mn(III) complexes that exhibit redox isomerism. The absence of isomerism for the iron complexes is explained in terms of thermodynamic changes that contribute to equilibria of the Co(N-N)(DBQ)(2) and Mn(N-N)(DBQ)(2) series.