Iron(III) compounds with long alkyl chains, [Fe(Cn-pap)2]ClO4 (Cn-pap: alkoxy-2-(2-pyridylmethyleneamino)phenol, n = 8 (1), 10 (2), 12 (3), 14 (4), 16 (5)) have been synthesized. The compounds were characterized by single crystal X-ray structure analysis and temperature dependent magnetic susceptibility in order to research the relationship between magnetic properties and the presence of long alkyl chains in soft molecules of the present type. The compounds 1, 2, 3 and 4 are in the high-spin (HS) state over the temperature range of 5 to 400 K. On the other hand, compound 5 is low-spin (LS) showing that the difference in magnetic properties depends on the length of the alkyl chain in the respective compounds.