Iron(II) pyridinecarboxamide complexes: Synthesis, crystal structures and magnetic properties

•Two mononuclear complexes of iron(II) pyridinecarboxamides have been synthesized.•In [Fe(pia)3]·(SO4)·3H2O ligands are in mer mode.•In (isnH)2[Fe(isn)2(SO4)2(H2O)2]·H2O ligands possess trans–octahedral geometry mode. Two new mononuclear complexes of iron(II) pyridinecarboxamides (picolinamide - pia, isonicotinamide - isn), [Fe(pia)3]·(SO4)·3H2O (1) and (isnH)2[Fe(isn)2(SO4)2(H2O)2]·H2O (2) have been synthesized by the reaction of iron(II) sulphate heptahydrate and pyridinecarboxamides in different solvents by standard method under reflux. Both compounds were characterized by single-crystal X-ray diffraction structure analysis, magnetic measurements and by FT-IR spectroscopy. In the complex cation of 1 Fe2+ ion is six coordinated by three nitrogen and three oxygen atoms from three bidentate picolinamide ligands in mer mode. In complex anion of 2 central Fe2+ ion is six coordinated by two isonicotinamide ligands, two sulphate ligands and two water molecules in trans mode. In both structures complex ions are connected with counterions and crystal water molecules with intermolecular hydrogen bonds. Magnetic properties of the compounds were measured between 2 K and 300 K giving the results: µeff = 4.5 BM for compound 1 and µeff = 4.7 BM for 2. Experimental values of the IR spectra are comparable with literature data and are in good agreement with results of the structural analysis.