Synthesis, crystal structure and properties of tetra­kis­(pyridine-3-carbo­nitrile)­dithio­cyanatoiron(II) and of diaqua­bis­(pyridine-3-carbo­nitrile)­di­thio­cyanatoiron(II) pyridine-3-carbo­nitrile monosolvate

The reaction of iron thio­cyanate with 3-cyano­pyridine (C(6)H(4)N(2)) leads to the formation of two compounds with the composition [Fe(NCS)(2)(C(6)H(4)N(2))(4)] (1) and [Fe(NCS)(2)(C(6)H(4)N(2))(2)(H(2)O)(2)]·2C(6)H(4)N(2) (2). The asymmetric unit of 1 consists of one iron cation, two thio­cyanate anions and four 3-cyano­pyridine ligands in general positions. The iron cation is octa­hedrally coordinated by two N-bonded thio­cyanate anions and four 3-cyano­pyridine ligands. The complexes are arranged in columns along the crystallographic c-axis direction and are linked by weak C—H⋯N inter­actions. In 2, the asymmetric unit consists of one iron cation on a center of inversion as well as one thio­cyanate anion, one 3-cyano­pyridine ligand, one water ligand and one 3-cyano­pyridine solvate mol­ecule in general positions. The iron cation is octa­hedrally coordinated by two N-bonded thio­cyanate anions, two cyano­pyridine ligands and two water ligands. O—H⋯N and C—H⋯S hydrogen bonding is observed between the water ligands and the solvent 3-cyano­pyridine mol­ecules. In the crystal structure, alternating layers of the iron complexes and the solvated 3-cyano­pyridine mol­ecules are observed. Powder X-ray (PXRD) investigations reveal that both compounds were obtained as pure phases and from IR spectroscopic measurements conclusions on the coordination mode of the thio­canate anions and the cyano­group were made. Thermogravimetric (TG) and differential thermoanalysis (DTA) of 1 indicate the formation of a compound with the composition {[Fe(NCS)(2)](3)(C(6)H(4)N(2))(4)}( n ) that is isotypic to the corresponding Cd compound already reported in the literature. TG/DTA of 2 show several mass losses. The first mass loss corresponds to the removal of the two water ligands leading to the formation of 1, which transforms into {[Fe(NCS)(2)](3)(C(6)H(4)N(2))(4)}( n ), upon further heating.