Fe(III) porphyrin complexes are known to show interesting spectroelectrochemical characteristics. To get further insight into the electrochemical properties, the spectroelectrochemistry measurements were carried out on the ligand H2TMPP and 1 in dichloromethane solvent using TBAPF6 as the supporting electrolyte at 300 K. All the potentials have been referenced with respect to ferrocene/ferrocenium. The spectral changes during the redox processes can be seen in K, the measured T value is 3.68 cm 3 mol -1 K using 1000 Oe applied dc field, which is lower than the spinonly T value of 4.375 cm 3 mol -1 K (S = 5/2, g = 2.0) that is expected for one Fe(III) centre in high-spin state. This lower T value suggesting that there may be a mixing of two different spin states, sextet 6 A1 and quartet 4 A2. On lowering the temperature, the T value decreases to a value of 2.83 cm 3 mol -1 K at 10 K and then abruptly decreases to 2.12 cm 3 mol -1 K at the lowest temperature (2 K) which is may be due to the combined effect of the zero-field splitting and the weak intermolecular antiferromagnetic interactions in the system. Upon increasing the temperature, the T value increases abruptly to 3.43 cm 3 mol -1 K at 50 K and then increases slightly to 3.68 cm 3 mol -1 K using 10000 Oe applied DC field, which remains constant up to 300 K (Figure ). was applied. This model describes the mixing of two different spin states, sextet 6 A1 and quartet 4 A2, separated by an energy gap  = ( 4 A2) -( 6 A1), through the spin-orbit coupling quantified by the  parameter. Generally, the 10x10 matrix must be solved to properly describe these spin-admixed states. Thus, a homemade model was made suitable to fit magnetic data. In such a way, we obtained  = 2605 cm - 1 and g = 1.82 for a fixed value of  = 432 cm -1 , which was taken from the respective CASSCF calculations (vide infra) (Figure ). These parameters imply that the 6 A1 state is split into three Kramers doublets with relative energies 0, 39.1, and 119.9 cm -1 , hence the value of ZFS parameter D can be estimated to be D ≈ + 20 cm -1 . The excited quartet Kramers states are located approximately at 3948 and 3987 cm -1 (Figure ).