Synthesis, crystal structure and thermal properties of poly[[µ-1,2-bis-(pyridin-4-yl)ethene-κ2N:N'-µ-bromido-copper(I)] 1,2-bis-(pyridin-4-yl)ethene 0.25-solvate].

The reaction of copper(I) bromide with 1,2-bis-(pyridin-4-yl)ethene in aceto-nitrile leads to the formation of the title compound, {[CuBr(C12H10N2)]·0.25C12H10N2}n or CuBr(4-bpe)·0.25(4-bpe) [4-bpe = 1,2-bis-(pyridin-4-yl)ethene]. The asymmetric unit consists of one copper(I) cation and one bromide anion in general positions as well as two crystallographically independent half 4-bpe ligands and a quarter of a disordered 4-bpe solvate mol-ecule that are completed by centers of inversion. The copper(I) cations are tetra-hededrally coordinated as CuBr2N2 and linked by pairs of µ-1,1-bridging bromide anions into centrosymmetric dinuclear units that are further connected into layers by the 4-bpe coligands. Between the layers, inter-layer C-H⋯Br hydrogen bonding is observed. The layers are arranged in such a way that cavities are formed in which the disordered 4-bpe solvate mol-ecules are located. Powder X-ray (PXRD) investigations reveal that a pure sample has been obtained. Thermogravimetric (TG) and differential thermoanalysis (DTA) measurements show two mass losses that are accompanied by endothermic events in the DTA curve. The first mass loss correspond to the removal of 0.75 4-bpe mol-ecules, leading to the formation of (CuBr)2(4-bpe), already reported in the literature as proven by PXRD.

Synthesis, crystal structure and properties of tetra-kis-(pyridine-3-carbo-nitrile)-dithio-cyanatoiron(II) and of diaqua-bis-(pyridine-3-carbo-nitrile)-di-thio-cyanatoiron(II) pyridine-3-carbo-nitrile monosolvate.

The reaction of iron thio-cyanate with 3-cyano-pyridine (C6H4N2) leads to the formation of two compounds with the composition [Fe(NCS)2(C6H4N2)4] (1) and [Fe(NCS)2(C6H4N2)2(H2O)2]·2C6H4N2 (2). The asymmetric unit of 1 consists of one iron cation, two thio-cyanate anions and four 3-cyano-pyridine ligands in general positions. The iron cation is octa-hedrally coordinated by two N-bonded thio-cyanate anions and four 3-cyano-pyridine ligands. The complexes are arranged in columns along the crystallographic c-axis direction and are linked by weak C-H⋯N inter-actions. In 2, the asymmetric unit consists of one iron cation on a center of inversion as well as one thio-cyanate anion, one 3-cyano-pyridine ligand, one water ligand and one 3-cyano-pyridine solvate mol-ecule in general positions. The iron cation is octa-hedrally coordinated by two N-bonded thio-cyanate anions, two cyano-pyridine ligands and two water ligands. O-H⋯N and C-H⋯S hydrogen bonding is observed between the water ligands and the solvent 3-cyano-pyridine mol-ecules. In the crystal structure, alternating layers of the iron complexes and the solvated 3-cyano-pyridine mol-ecules 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 thio-canate anions and the cyano-group were made. Thermogravimetric (TG) and differential thermoanalysis (DTA) of 1 indicate the formation of a compound with the composition {[Fe(NCS)2]3(C6H4N2)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(C6H4N2)4}n, upon further heating.

Synthesis, crystal structure and properties of chlorido-tetra-kis-(pyridine-3-carbo-nitrile)-thio-cyanato-iron(II).

Reaction of FeCl2·4H2O with KSCN and 3-cyano-pyridine (pyridine-3-carbo-nitrile) in ethanol accidentally leads to the formation of single crystals of Fe(NCS)(Cl)(3-cyano-pyridine)4 or [FeCl(NCS)(C6H4N2)4]. The asymmetric unit of this compound consists of one FeII cation, one chloride and one thio-cyanate anion that are located on a fourfold rotation axis as well as of one 3-cyano-pyridine coligand in a general position. The FeII cations are sixfold coordinated by one chloride anion and one terminally N-bonding thio-cyanate anion in trans-positions and four 3-cyano-pyridine coligands that coordinate via the pyridine N atom to the FeII cations. The complexes are arranged in columns with the chloride anions, with the thio-cyanate anions always oriented in the same direction, which shows the non-centrosymmetry of this structure. No pronounced inter-molecular inter-actions are observed between the complexes. Initially, FeCl2 and KSCN were reacted in a 1:2 ratio, which lead to a sample that contains the title compound as the major phase together with a small amount of an unknown crystalline phase, as proven by powder X-ray diffraction (PXRD). If FeCl2 and KSCN is reacted in a 1:1 ratio, the title compound is obtained as a nearly pure phase. IR investigations reveal that the CN stretching vibration for the thio-cyanate anion is observed at 2074 cm-1, and that of the cyano group at 2238 cm-1, which also proves that the anionic ligands are only terminally bonded and that the cyano group is not involved in the metal coordination. Measurements with thermogravimetry and differential thermoanalysis reveal that the title compound decomposes at 169°C when heated at a rate of 4°C min-1 and that the 3-cyano-pyridine ligands are emitted in two separate poorly resolved steps. After the first step, an inter-mediate compound with the composition Fe(NCS)(Cl)(3-cyano-pyridine)2 of unknown structure is formed, for which the CN stretching vibration of the thio-cyanate anion is observed at 2025 cm-1, whereas the CN stretching vibration of the cyano group remain constant. This strongly indicates that the FeII cations are linked by µ-1,3-bridg-ing thio-cyanate anions into chains or layers.