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Two different isomers of [Co(NCS)

Reaction of Ni(NCS)2 with 4-(Boc-amino)pyridine in acetonitrile leads to the formation of a new coordination polymer with the composition Ni(NCS)2(4-(Boc-amino)pyridine)2·MeCN (1-MeCN). In the crystal structure the Ni(II) cations are linked by the anionic ligands into chains that are further connected into layers by intermolecular N–H···O hydrogen bonding. These layers are stacked and channels are formed, in which acetonitrile molecules are located. Solvent removal leads to the ansolvate 1, which shows microporosity as proven by sorption measurements. Single crystal X-ray investigations reveal that the solvent removal leads to a change in symmetry from primitive to C-centered, which is reversible and which proceeds via a topotactic reaction leaving the network intact. The magnetic properties of 1-MeCN and 1 are governed by the ferromagnetic exchange between spins of Ni(II) forming chains. The susceptibility and specific heat for such a quantum Heisenberg chain of S = 1 spins with zero-field splitting are ...

Reaction of Co(NCS)2 with 2,6-dimethylpyrazine (2,6-DMPy) leads to the formation of a compound with the composition Co(NCS)2(2,6-DMPy)4 (Co-0D) that consists of discrete complexes, in which the Co cations are octahedrally coordinated. Upon heating, half of the 2,6-DMPy ligands are removed leading to the two-dimensional coordination polymer [Co(NCS)2(2,6-DMPy)2]n (Co-2D), shown by thermogravimetry and X-ray powder diffraction. On further heating, the intermediate Co-2D loses the next 2,6-DMPy ligand and transforms into [Co(NCS)2(2,6-DMPy)]n (Co-3D). The crystal structures of Co-2D and Co-3D were solved and refined using powder X-ray diffraction data. The crystal structure of Co-2D consists of octahedrally coordinated Co cations that are linked by pairs of anionic ligands into dimers, which are further connected by single thiocyanate anions into layers. In Co-3D, octahedrally and tetrahedrally coordinated Co cations are present, that are linked by μ-1,3-bridging single thiocyanate anions into a novel three-...

Reaction of Mn(NCS)2 and Cd(NCS)2 with 4-(Boc-amino)pyridine leads to the formation of compounds of composition M(NCS)2(4-(Boc-amino)pyridine)4 (M = Mn, 1-Mn; Cd, 1-Cd) and (M(NCS)2(4-(Boc-amino)pyridine)2 (M = Mn, 2-Mn; Cd, 2-Cd). 1-Cd and 1-Mn, respectively 2-Cd and 2-Mn are isotypic and their structures were determined by X-ray single crystal or powder diffraction. 1-Mn and 1-Cd consist of discrete complexes, whereas in 2-Mn and 2-Cd the cations are linked into chains by μ-1,3-bridging anionic ligands. On heating 1-Cd and 1-Mn, mass steps are observed that indicate formation of compounds of composition M(NCS)2(4-(Boc-amino)pyridine)2, but ex-situ XRPD investigations prove that amorphous intermediates are obtained. In contrast, temperature dependent XRPD measurements for 1-Cd indicate the formation of an unknown crystalline phase. Magnetic measurements on 2-Mn show dominating antiferromagnetic interactions along the chain and at TN = 22.0 K antiferromagnetic ordering is observed. 1-Cd and 2-Cd show bluish ligand-based luminescence with emission maxima at, respectively 22,301 cm−1 and 20,678 cm−1, while 1-Mn and 2-Mn present metal-based luminescence in the yellow spectral range with emission maxima at 18,382 cm−1.

Two different isomers of [Co(NCS)2(4-chloropyridine)2]n (3C and 3L) were synthesized from solution and by thermal decomposition of Co(NCS)2(4-chloropyridine)2(H2O)2 (2), which show a different meta...

Two new transition metal thiocyanate coordination polymers with the composition [Co(NCS)2(4-vinylpyridine)2]n (1) and [Co(NCS)2(4-benzoylpyridine)2]n (2) were synthesized and their crystal structures were determined. In both compounds the Co cations are octahedrally coordinated by two trans-coordinating 4-vinyl- or 4-benzoylpyridine co-ligands and four μ-1,3-bridging thiocyanato anions and linked into chains by the anionic ligands. While in 1 the N and the S atoms of the thiocyanate anions are also in trans-configuration, in 2 they are in cis-configuration. A detailed magnetic study showed that the intra-chain ferromagnetic coupling is slightly stronger for 2 than for 1, and that the chains in both compounds are weekly antiferromagnetically coupled. Both compounds show a long range magnetic ordering transition at Tc = 3.9 K for 1 and Tc = 3.7 K for 2, which is confirmed by specific heat measurements. They also show a metamagnetic transition at a critical field of 450 Oe (1) and 350 Oe (2), respectively. Below Tc1 and 2 exhibit magnetic relaxations resembling relaxations of single chains. The exchange constants obtained from magnetic and specific heat data are in good accordance with those obtained from constrained DFT calculations carried out on isolated model systems. The ab initio calculations allowed us to find the principal directions of anisotropy.

Reaction of manganese (II) thiocyanate with 2,5-dimethylpyrazine leads to the formation of three new coordination compounds of compositions Mn(NCS)2(2,5-dimethylpyrazine)2(H2O)2(1), Mn(NCS)2(H2O)2(MeOH)2-tris(2,5-dimethylpyrazine) solvate (2), and Mn(NCS)2(H2O)4-tetrakis(2,5-dimethylpyrazine) solvate (3) that were characterized by single crystal X-ray diffraction. In their crystal structures, the Mn(II) cations are sixfold coordinated by two terminally N-bonded thiocyanato anions and two water molecules as well as by two 2,5-dimethylpyrazine ligands (1), two ethanol (2), or two water molecules (3), within slightly distorted octahedra. In compounds2and3, additional 2,5-dimethylpyrazine ligands are located in the cavities of the structures as solvate molecules. X-ray powder diffraction has shown that compounds1and2cannot be prepared as pure phases and that batches of compound3contain only minor traces of a contamination. Differential thermoanalysis and thermogravimetry have revealed that upon heating of compound3, an intermediate of composition Mn(NCS)2(2,5-dimethylpyrazine) (4) is formed, which cannot be obtained from solution. To mimic the structure of4, single crystals of a Cd compound of the same composition (5) were prepared from the liquid phase, and single crystal X-ray analysis has shown that it is isotypic to4.

Reaction of Ni(NCS)

Invited for the cover of this issue is the group of Christian Nather at the University of Kiel, Germany. The cover image shows the structures of two isomeric coordination polymers that are located somewhere on an energy hypersurface. This is represented by the desert landscape; the thermodynamically stable structure is located in the valley, whereas the metastable one is located on the mountain.

Reaction of manganese(II) thiocyanate with the monodentate ligand 4-benzylpyridine (bp) leads to the formation of two compounds of composition Mn(NCS)2(4-benzylpyridine)4 (1-bp) and Mn(NCS)2(4-benzylpyridine)2 (2-bp). Compound 1-bp forms discrete complexes in which the Mn cations are coordinated by four 4-benzylpyridine ligands and two terminal N-bonding thiocyanato anions within slightly distorted octahedra. In compound 2-bp the metal cations are surrounded by two cis-coordinating 4-benzylpyridine ligands, two cis-coordinating S-bonded thiocyanato anions and two trans-coordinating N-bonded anionic ligands. The Mn cations are linked into zig–zag-like chains by pairs of μ-1,3-bridging anionic ligands. DTA–TG measurements on 1-bp prove that 2-bp is obtained as intermediate. Magnetic measurements on the chain compound 2-bp show dominating antiferromagnetic interactions between the Mn centers. On cooling a maximum is observed in the susceptibility curve indicative for an antiferromagnetic transition. The results of the magnetic measurements are compared with those obtained for other Mn thiocyanato chain compounds in which the thiocyanato anions are trans-coordinated.

Reaction of cobalt thiocyanate with 4-acetylpyridine leads to the formation of [Co(NCS)2(4-acetylpyridine)2]n (3/I). In its crystal structure the Co cations are connected by pairs of μ-1,3-bridging thiocyanato ligands into dimers that are further connected into layers by single anionic ligands. DTA-TG measurements of Co(NCS)2(4-acetyl-pyridine)4 (1) led to the formation of 3/I. In contrast, when the hydrate Co(NCS)2(4-acetyl-pyridine)2(H2O)2 (2) is decomposed, a mixture of 3/I and a thermodynamically metastable form 3/II is obtained. Further investigations reveal that thermal annealing of 2 leads to the formation of 3/II, that contains only traces of the stable form 3/I. DSC and temperature dependent X-ray powder diffraction (XRPD) measurements prove that 3/II transforms into 3/I on heating. The crystal structure of 3/II was determined ab initio from XRPD data. In its crystal structure the Co cations are linked by pairs of bridging thiocyanato anions into a 1D coordination polymer, and thus, 3/II is an isomer of 3/I. Magnetic measurements disclose that the stable form 3/I only shows paramagnetism without any magnetic anomaly down to 2 K. In contrast, the metastable form 3/II shows ferromagnetic behavior. The phase transition into ordered state at Tc = 3.8 K was confirmed by specific heat measurements. Alternating current susceptibility measurements show frequency dependent maxima in χ' and χ″, which is indicative for a slow relaxation of the magnetization.

The crystal structure of the title compound consists of discrete octa­hedral complexes that are linked by inter­molecular O—H⋯S, C—H⋯Cl, C—H⋯S and C—H⋯Cl hydrogen bonding., The asymmetric unit of the title compound, [Ni(NCS)2(C5H4ClN)2(H2O)2], consists of one nickel(II) cation that is located on a center of inversion and one thio­cyanate anion, one water mol­ecule and one 2-chloro­pyridine ligand all occupying general positions. The NiII cation is octa­hedrally coordinated by two terminal N-bound thio­cyanato ligands, two aqua ligands and two N-bound 2-chloro­pyridine ligands into discrete complexes. Individual complexes are linked by inter­molecular O—H⋯S and O—H⋯Cl hydrogen-bonding inter­actions into a layered network extending parallel to the bc plane. Weak inter­actions of types C—H⋯S and C—H⋯Cl consolidate the crystal packing.

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(N...

The crystal structure of the title compound consists of discrete octa­hedral complexes that are linked by inter­molecular O—H⋯O hydrogen bonding into layers., The crystal structure of the title compound, [Co(NCS)2(C12H9NO)2(CH3OH)2], consists of cobalt(II) cations that are octa­hedrally coordinated by two N-terminal bonding thio­cyanato anions, two methanol mol­ecules and two 4-benzoyl­pyridine ligands into discrete complexes that are located on centres of inversion. These complexes are further linked by O—H⋯O hydrogen bonding between the hy­droxy H atom of the methanol ligand and the carbonyl O atom of the 4-benzoyl­pyridine ligand of a neighboring complex into layers parallel to (101). No pronounced inter­molecular inter­actions are observed between these layers.

The crystal structure of the title compound consists of discrete octa­hedral complexes, that are linked by inter­molecular C—H⋯O and C—H⋯S hydrogen bonding into layers., The crystal structure of the title compound, [Co(NCS)2(C2H3N)2(C12H9NO)2], consists of cobalt(II) cations that are octa­hedrally coordinated by the N atoms of two terminal thio­cyanate anions, two aceto­nitrile mol­ecules and two 4-benzoyl­pyridine ligands. The discrete complexes are located on centres of inversion. They are connected by weak inter­molecular C—H⋯O and C—H⋯S hydrogen-bonding inter­actions between one of the pyridine H atoms and the carbonyl O atom, and between one of the methyl H atoms of the aceto­nitrile mol­ecule and the thio­cyanate S atoms into layers parallel to (101). No pronounced inter­molecular inter­actions are observed between these layers.

Two new transition metal thiocyanate coordination polymers with the composition [Co(NCS)

Reaction of cobalt(II) and nickel(II) thiocyanate with ethylisonicotinate leads to the formation of [M(NCS)2(ethylisonicotinate)2]n with M = Co (2-Co) and M = Ni (2-Ni), which can also be obtained by thermal decomposition of M(NCS)2(ethylisonicotinate)4 (M = Co (1-Co), Ni (1-Ni)). The crystal structure of 2-Ni was determined by single crystal X-ray diffraction. The Ni(II) cations are octahedrally coordinated by two N and two S bonding thiocyanate anions and two ethylisonicotinate ligands and are linked by pairs of anionic ligands into dimers, that are connected into layers by single thiocyanate bridges. The crystal structure of 2-Co was refined by Rietveld analysis and is isostructural to 2-Ni. For both compounds ferromagnetic ordering is observed at 8.7 K (2-Ni) and at 1.72 K (2-Co), which was also confirmed by specific heat measurements. Similar measurements on [Co(NCS)2(4-acetylpyridine)2]n that exhibits the same layer topology also prove magnetic ordering at 1.33 K. Constrained DFT calculations (CDFT) support the ferromagnetic interactions within the layers. The calculated exchange constants in 2-Ni were used to simulate the susceptibility by quantum Monte Carlo method. The single-ion magnetic anisotropy of the metal ions has been investigated by CASSCF/CASPT2 calculations indicating significant differences between 2-Ni and 2-Co.

Reaction of Co(NCS)2 with 4-(hydroxymethyl)pyridine (hmpy) leads to the formation of six new coordination compounds with the composition [Co(NCS)2(hmpy))4] (1), [Co(NCS)2(hmpy)4] × H2O (1-H2O), [Co(NCS)2(hmpy)2(EtOH)2] (2), [Co(NCS)2(hmpy)2(H2O)2] (3), [Co(NCS)2(hmpy)2]n∙4 H2O (4) and [Co(NCS)2(hmpy)2]n (5). They were characterized by single crystal and powder X-ray diffraction experiments, thermal and elemental analysis, IR and magnetic measurements. Compound 1 and 1-H2O form discrete complexes, in which the Co(II) cations are octahedrally coordinated by two terminal thiocyanato anions and four 4-(hydroxymethyl)pyridine ligands. Discrete complexes were also observed for compounds 2 and 3 where two of the hmpy ligands were substituted by solvent, either water (3) or ethanol (2). In contrast, in compounds 4 and 5, the Co(II) cations are linked into chains by bridging 4-(hydroxymethyl)pyridine ligands. The phase purity was checked with X-ray powder diffraction. Thermogravimetric measurements showed that compound 3 transforms into 5 upon heating, whereas the back transformation occurs upon resolvation. Magnetic measurements did not show any magnetic exchange via the hmpy ligand for compound 5.

In the crystal structure of the title compound, [Co(NCS)2(C6H8N2)2(H2O)2]·3C6H8N2, the CoIIcation is coordinated by two terminallyN-bound thiocyanate anions, two water molecules and two 2,6-dimethylpyrazine ligands, forming a discrete complex with a slightly distorted octahedral N4O2coordination environment. The asymmetric unit contains one CoIIcation and three halves of 2,5-dimethylpyrazine solvate molecules, all entities being completed by inversion symmetry, as well as one thiocyanate anion, an aqua ligand and a 2,6-dimethylpyrazine ligand, all in general positions. In the crystal, discrete complexes are arranged in a way that cavities are formed where the noncoordinating 2,5-dimethylpyrazine molecules are located. The coordination of the latter to the metal is prevented due to the bulky methyl groups in vicinal positions to the N atoms, leading to a preferential coordination through the 2,6-dimethylpyrazine ligands. The complex molecules are linked by O—H...N hydrogen bonds between the water H atoms and the N atoms of 2,5-dimethylpyrazine solvent molecules, leading to a layered structure extending parallel to (100).

In the crystal structure of the title compound, [Ni(NCS)2(H2O)4]·4C6H8N2, the NiIIcations are coordinated by four water ligands and twotrans-coordinated terminallyN-bonded thiocyanate anions in a slightly distorted octahedral geometry. The asymmetric unit consists of a Ni2+cation located on a centre of inversion, two water molecules and one thiocyanate ligand, as well as two uncoordinated 2,5-dimethylpyrazine ligands in general positions. In the crystal, discrete complex molecules are linked into a three-dimensional network by O—H...N hydrogen bonding between the water H atoms and the 2,5-dimethylpyrazine N atoms.

In the crystal structure of the mononuclear title compound, [Mn(NCS)2(C10H8N2)2]·C10H8N2, the MnIIcation is coordinated in an all-cisconfiguration by two N-bound thiocyanate anions and two 2,2′-bipyridine ligands within a slightly distorted octahedral environment. The asymmetric unit consists of one MnIIcation, two thiocyanate anions and two 2,2′-bipyridine ligands, as well as two non-coordinating 2,2′-bipyridine ligands that are each located on centres of inversion. In the crystal structure, the discrete [Mn(NCS)2(C10H8N2)2] complex molecules are arranged in such a way that cavities are formed, in which the solvent 2,2′-bipyridine molecules are located. Apart from van der Waals forces, there are no remarkable intermolecular interactions present in the crystal structure.

In the crystal structure of the polymeric title compound, [Mn(NCS)2(C10H8N2)]n, the MnIIcations are coordinated by one chelating 2,2′-bipyridine ligand and four thiocyanate anions (twoN- and twoS-coordinating), forming a distorted [MnN4S2] octahedron. The asymmetric unit consists of one manganese cation located on a twofold rotation axis and half of a 2,2′-bipyridine ligand, the other half being generated by the same twofold rotation axis, as well as one thiocyanate anion in a general position. The MnIIcations are linked by two pairs of μ1,3-bridging thiocyanate ligands into chains along thecaxis; because the N atoms of the 2,2′-bipyridine ligands, as well as the N and the S atoms of the thiocyanate anions, are eachcis-coordinating, these chains show a zigzag arrangement.

In the crystal structure of the title compound, [Co(NCS)2(C6H8N2)2(H2O)2]·C6H8N2, the CoIIcation is coordinated by the N atoms of two terminal thiocyanate anions, the O atoms of two water molecules and two N atoms of two 2,6-dimethylpyrazine ligands. The coordination sphere of the resulting discrete complex is that of a slightly distorted octahedron. The asymmetric unit comprises a CoIIcation and half of a 2,5-dimethylpyrazine ligand, both of which are located on centres of inversion, and a water ligand, a 2,6-dimethylpyrazine ligand and one thiocyanate anion in general positions. In the crystal, the discrete complexes are arranged in such a way that cavities are formed in which the 2,5-dimethylpyrazine solvent molecules are located. The coordination of the 2,5-dimethylpyrazine molecules to the metal is apparently hindered due to the bulky methyl groups in vicinal positions to the N atoms, leading to a preferential coordination of the 2,6-dimethylpyrazine ligands. The discrete complexes are linked by O—H...N hydrogen bonds between one water H atom and the non-coordinating N atom of the 2,6-dimethylpyrazine ligands. The remaining water H atom is hydrogen bonded to one N atom of the 2,5-dimethylpyrazine solvent molecule. This arrangement leads to the formation of a two-dimensional network extending parallel to (010).

In the crystal structure of the title complex, [Mn(NCS)2(C6H8N2)(H2O)3]·2C6H8N2, the MnIIcation is coordinated by two terminallyN-bonded thiocyanate anions, three water molecules and one 2,6-dimethylpyrazine ligand within a slightly distorted N3O3octahedral geometry; the entire complex molecule is generated by the application of a twofold rotation axis. The asymmetric unit also contains an uncoordinating 2,5-dimethylpyrazine ligand in a general position. Obviously, the coordination to the 2,6-dimethylpyrazine ligand is preferred because coordination to the 2,5-dimethylpyrazine is hindered due to the bulky methyl group proximate to the N atom. The discrete complexes are linked by water-O—H...N(2,6-dimethylpyzazine/2,5-dimethylpyzazine) hydrogen bonding, forming a three-dimensional network. In the crystal, molecules are arranged in a way that cavities are formed in which unspecified, disordered solvent molecules reside. These were modelled employing the SQUEEZE routine inPLATON[Spek (2015).Acta Cryst. C71, 9–18]. The composition of the unit cell does not take into account the presence of the unspecified solvent.

In the crystal structure of the title compound, [Mn(C5H7O2)2(C12H8N2)], the Mn2+cation is coordinated by one bidentate 1,10-phenanthroline ligand and two acetylacetonate anions within a slightly distorted N2O4octahedron. The asymmetric unit consists of one Mn2+cation situated on a twofold rotation axis, one half of a 1,10-phenanthroline ligand and one acetylacetonate anion. In comparison with the previous determination based on visually estimated intensities recorded on precession photographs, the current redetermination with image-plate data reveals bond lengths and angles with much higher precision.