Tristan Neumann

Structures, Thermodynamic Relations, and Magnetism of Stable and Metastable Ni(NCS)2 Coordination Polymers

Reaction of Ni(NCS)2 with 4-aminopyridine in different solvents leads to the formation of compounds with the compositions Ni(NCS)2(4-aminopyridine)4 (1), Ni(NCS)2(4-aminopyridine)2(H2O)2 (2), [Ni(NCS)2(4-aminopyridine)3(MeCN)]·MeCN (3), and [Ni(NCS)2(4-aminopyridine)2] n (5-LT). Compounds 1, 2, and 3 form discrete complexes, with octahedral metal coordination. In 5-LT the Ni cations are linked by single thiocyanate anions into chains, which are further connected into layers by half of the 4-aminopyridine coligands. Upon heating, 1 transforms into an isomer of 5-LT with a 1D structure (5-HT), that on further heating forms a more condensed chain compound [Ni(NCS)2(4-aminopyridine)] n (6) that shows a very unusual chain topology. If 3 is heated, a further compound with the composition Ni(NCS)2(4-aminopyridine)3 (4) is formed, which presumably is a dimer and which on further heating transforms into 6 via 5-HT as intermediate. Further investigations reveal that 5-LT and 5-HT are related by enantiotropism, with 5-LT being the thermodynamic stable form at room-temperature. Magnetic and specific heat measurements reveal ferromagnetic exchange through thiocyanate bridges and magnetic ordering due to antiferromagnetic interchain interactions at 5.30(5) K and 8.2(2) K for 5-LT and 6, respectively. Consecutive metamagnetic transitions in the spin ladder compound 6 are due to dipolar interchain interactions. A convenient formula for susceptibility of the ferromagnetic Heisenberg chain of isotropic spins S = 1 is proposed, based on numerical DMRG calculations, and used to determine exchange constants.

Crystal structure of bis­(isonicotinamide-κN1)bis­(thio­cyanato-κN)zinc

The crystal structure consists of discrete tetrahedral complexes, that are linked by intermolecular N—H⋯O, C—H⋯O and N—H⋯O hydrogen bonding.

catena-Poly[[bis­(pyridine-κN)nickel(II)]-di-μ-thio­cyanato-κ2N:S;κ2S:N]

In the title compound, [Ni(NCS)2(C5H5N)2]n, the Ni2+ cation is coordinated by four thiocyanate anions (μ-1,3) and two pyridine ligands within a slightly distorted octahedral configuration. The Ni—N bond lengths to the pyridine rings are 2.1189 (17) and 2.1241 (17) Å, whereas those to the thiocyanate anions are 2.0299 (18) and 2.0359 Å. The Ni—S bond lengths are 2.5357 (6) and 2.5568 (6) Å. The Ni2+ cations are linked by N:S-bridging thiocyanate ligands into chains extending along [010]. The Ni⋯Ni distance within the chains is 5.5820 (5) Å. The asymmetric unit contains two Ni2+ cations of which one is located on a centre of inversion, whereas the second is located on a general position.

Crystal structures of tetra­kis­(pyridine-4-thio­amide-κN)bis­(thio­cyanato-κN)cobalt(II) monohydrate and bis­(pyridine-4-thio­amide-κN)bis­(thio­cyanato-κN)zinc(II)

The crystal structures of the title compounds consists of discrete octahedral (Co) or tetrahedral (Zn) complexes that are linked by intermolecular hydrogen-bonding interactions into three-dimensional networks.

Crystal structure of bis(pyridine-4-carbothioamide-κN1)bis(thiocyanato-κN)cobalt(II) methanol monosolvate

The crystal structure of the title compound consists of discrete octahedral complexes that are linked by intermolecular N—H⋯S hydrogen bonds into a three-dimensional network that contains channels in which the hydrogen-bonded methanol molecules are located.

Crystal structure of tetra-kis-(isonicotinamide-κN)bis-(thio-cyanato-κN)cobalt(II)-isonicotinamide-ethanol (1/2/1).

The crystal structure of the title compound consists of discrete octahedral cobalt(II) complexes that are linked by a variety of hydrogen-bonding interactions into a three-dimensional network.

Crystal structure of catena-poly[[[bis­(pyridine-4-carbo­thio­amide-κN1)cadmium]-di-μ-thio­cyanato-κ2N:S;κ2S:N] methanol disolvate]

The crystal structure of the title compound consists of CdII cations that are linked by thiocyanato anions into chains which are further connected into layers by intermolecular N—H⋯O and O—H⋯S hydrogen bonding via additional methanol molecules.

Poly[(μ-1,3-thio­cyanato-κN,S)(iso­nicotin­ato-κN,O)(ethanol-κO)cadmium(II)]

In the crystal structure of the title compound, [Cd(NCS)(C6H4NO2)(C2H5OH)]n, the Cd2+ cation is coordinated by one N and two O atoms of two symmetry-related isonicotinate anions, one ethanol molecule and two μ-1,3-bridging thiocyanate anions in a distorted octahedral N2O3S geometry. The metal cations are μ-1,3-bridged via thiocyanate anions into chains that are further connected into layers parallel to the ab plane by bridging isonicotinate anions. The layers are stacked along the c axis. The crystal structure is stabilized by O—H⋯O hydrogen bonds.

Cd(II) and Zn(II) thiocyanate coordination compounds with 3-ethylpyridine: synthesis, crystal structures and properties

Abstract Reaction of Cd(NCS)2 and Zn(NCS)2 with 3-ethylpyridine leads to the formation of compounds of compositions M(NCS)2(3-ethylpyridine)4 (M=Cd, 1-Cd; Zn, 1-Zn) and M(NCS)2(3-ethylpyridine)2 (M=Cd, 2-Cd; Zn, 2-Zn). 1-Cd and 1-Zn are isotypic and form discrete complexes in which the metal cations are octahedrally coordinated by two trans-coordinating N-bonded thiocyanate anions and four 3-ethylpyridine co-ligands. In 2-Cd the cations are also octahedrally coordinated but linked into chains by pairs of μ-1,3-bridging anionic ligands. 2-Zn is built up of discrete complexes, in which the Zn cation is tetrahedrally coordinated by two N-bonded thiocyanate anions and two 3-ethylpyridine co-ligands. Compounds 1-Cd, 2-Cd and 2-Zn can be prepared in a pure state, whereas 1-Zn is unstable and transforms on storage into 2-Zn. If 1-Cd and 1-Zn are heated, a transformation into 2-Cd, respectively 2-Zn is observed. Luminescence measurements reveal that 1-Cd, 2-Cd and 2-Zn emit light in the blue spectral range with maxima at, respectively, 21724, 21654 and 22055 cm−1, assigned to ligand-based luminescence.

Crystal structures of bis­[4-(di­methyl­amino)­pyridinium] tetra­kis­(thio­cyanato-κN)manganate(II) and tris­[4-(di­methyl­amino)­pyridinium] penta­kis(thio­cyanato-κN)manganate(II)

The crystal structures of the title salts consist of discrete anionic complexes, in which the MnII atom is either in a distorted tetrahedral or a trigonal–bipyramidal coordination environment by terminal N-bonding thiocyanate ligands. The complex anions are charge-balanced by two or three 4-(dimethylamino)pyridinium cations.