Magnetic susceptibility and M\"{o}ssbauer studies of [FeX$_{3}$](ClO$_{4}$)$_{2}$$\cdot$H$_{2}$O with X = bpz, bpy, phen or tpy

Magnetic studies have been made on several tris-chelated iron complex compounds [FeX$_{3}$](ClO$_{4})_{2}\cdot $H$_{2}$O with aromatic nitrogen heterocycle ligands X = bpz (2,2'-bipyrazine), bpy (2,2'-bipyridine), phen (1,10-phenanthroline) or tpy (2,2':6,2''-terpyridine). SQUID data (2-300 K and 0.01-1 T) yielded small effective magnetic moments, which are characteristic of low-spin Fe(II), in agreement with the isomer shift and quadrupole splitting values from M\"{o}ssbauer measurements (4-300 K, 0-5 T). Meanwhile, apart from the expected diamagnetism, a positive term of temperature-independent paramagnetic susceptibility prevails in most cases.