High-spin and low-spin complexes of the iron(III) tetrakis(meso-cyclohexyl)porphyrin (TCHP)Fe-III) have been studied by means of 1-D and 2-D H-1 NMR. The complete assignment of porphyrin and R-imidazole H-1 resonances has been done on the basis of 2-D COSY and NOESY techniques as well as by selective deuteration of imidazole. The chemical shifts of pyrrole beta-Hs have been used as the probe of the electronic state of an iron(III) metal ion. It has been found that cyanide coordinates to the high-spin (TCHP)(FeCl)-Cl-III complex, leading to the formation of the low-spin [(TCHP)Fe-III(CN2)](-), with the rare (d(xz)d(yz))(4)(d(xy))(1) ground electronic state (the pyrrole beta-H resonance at 12.01 ppm at 293 K in CD3OD). A contribution of two electronic configurations, (d(xy))(2)(d(xz)d(yz))(3) and (d(xz)d(yz))(4)(d(xy))(1), to the ground state of the metal ion has been invoked for the low-spin [(TCHP)Fe-III(R-Im)(2)](+) complexes Characteristic H-1 NMR shifts for these complexes include the pyrrole resonance at 2.81 ppm accompanied by the markedly upfield shifted imidazole resonances at -19.67 ppm (2-H), -10.58 ppm (4-H), -4.05 ppm (5-H), and 0.97 ppm (1-H). An admixture of a (d(xz)d(yz))(4)(d(xy))(1) configuration into the ground electronic state increases in the order imidazole (ImH) < 1-methylimidazole (1-MeIm) < 1,2-dimethylimidazole (1,2-diMeIm), following an enlargement of the axial ligand steric hindrance. The rotation of the 1,2-diMeIm around Fe-N bond in the low-spin [(TCHP)Fe-III(1,2-diMeIm)(2)](+) complex is slow on the H-1 NMR time scale even at 293 K. Consequently four beta-H resonances and the diastereotopy of the cyclohexyl meso-substituents have been observed. The meso-cyclohexyl groups rotate freely at temperature above 243 K, whereas the frozen rotation below 233 K leads to the formation of additional rotational isomers as demonstrated by multiplicity of beta-H resonances for high-spin and low-spin complexes studied.