Two new complexes, [Fe(3,5-Br-salEen)2]ClO4·EtOH (5) and [Fe(3,5-Br-salEen)2]BPh4·DMF (6) were synthesised and their magnetic properties investigated. The crystal packing diagram of complex 6 showed that the interaction between the metal centres is obstructed by the anion, affecting the SCO behaviour. SQUID magnetometry and Mössbauer spectroscopy showed that while 6 presents a gradual and incomplete SCO, 5 stabilises in the LS state up to 300 K. Comparison of the solid state magnetic profiles of newly reported complexes 5 and 6 with previously reported complexes 1–4 did not allow to draw conclusions on the influence of ligand substituent (σ-inductive electron withdrawing groups – bromine) on their magnetic behaviour. However, both spectroscopic and electrochemical studies of the complexes in solution have shown that there is a clear effect on their properties depending on the degree of substitution at the phenolate ring. Interestingly, both UV–vis measurements and Evans magnetic susceptibility determinations at concentrations separated by a factor of ≈100 (0.07 mM for UV–vis and 5 mM for Evans' method) confirmed the effect of the ligand substituents on their magnetic character. The results indicate that in solution complex 1 is essentially in the HS state, and both HS and LS forms are present for the other complexes. When compared to the unsubstituted complexes (1 and 2), a significant decrease on χmT is observed when two bromide substituents are present at the phenolate ring, showing a clear preference for the LS state, and indicating an increased separation between the t2g and eg* energy levels. The bromide substituent effect has also been observed on the electrochemical behaviour of the complexes. The reduction of the metallic centres proved to be easier for ligands with increasing number of electron withdrawing groups, as the E1/2 values of iron shift to more positive potentials.