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A large single crystal of a compound from the family of coordination polymer [Co(NCS)2(L)2]n chains was synthesized and its magnetic properties are reported. [Co(NCS)2(4-(3-phenylpropyl)pyridine)2]n is ferromagnetic with Tc = 3.39 K. Single-ion ab initio calculations predict an almost Ising-type magnetic anisotropy and the direction of the magnetic easy-axis nearly along the Co–Npy bond of the apical pyridine-based co-ligand. Both predictions are confirmed by single-crystal magnetic measurements. The magnetic relaxation of the single crystal sample significantly differs from the powder sample data, and clearly shows the presence of two separate relaxation processes. The process dominant below 3.2 K demonstrates a single chain magnet (SCM) behaviour, with a crossover between single-wall and two-wall processes, in spite of the fact that the system is ferromagnetically ordered. The faster process that dominates just below Tc is attributed to spin waves. Micromagnetic Monte Carlo simulations of the investigated compound show that the dipolar field cancels for some chains located at the border between 3-dimensional domains. Such chains are responsible for the measured ac signal, and demonstrate the SCM behaviour. The quantitative analysis of the SCM relaxation time is supported by preparing and examining a corresponding diamagnetically diluted compound, [CoxCd1−x(NCS)2(4-(3-phenylpropyl)pyridine)2]n (x = 0.013), which behaves as a field-induced single-ion magnet. The relaxation pathways for single Co(II) spins are determined to be Raman, direct, and quantum tunneling processes, which were included in an improved approach to describe the magnetic relaxation in the Co(II)-based SCM compound.

Reaction of FeCl2, KSCN, and 4-acetylpyridine in dry ethanol leads to [Fe(NCS)2(4-acetylpyridine)2]n (1-Fe) that, in contrast to the previously reported chain isomer, consists of layers. Specific h...

Reaction of Co(NCS)2 and Ni(NCS)2 with 4-tert-butylpyridine in ethyl acetate leads to the formation of mixed crystals of a layered compound with the composition [CoxNi1-x(NCS)2(4-tert-butylpyridine]n. The mixed crystal formation was investigated by a combination of atomic absorption spectroscopy, X-ray powder diffraction and IR spectroscopy. Magnetic and specific heat measurements prove dominating ferromagnetic exchange interactions within the layers and a ferromagnetic transition. Depending on the synthetic method, inhomogeneous samples were obtained, for which predominantly the large difference in the solubility of the homometallic compounds might be responsible. Very long reaction time leads to much better samples for which a distinct critical temperature is observed that increases smoothly with increasing Ni content.

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 Co(NCS)2 with different coligands leads to the formation of three compounds with the general composition [Co(NCS)2(L)2]n (L = aniline (1), morpholine (2), and ethylenethiourea (3)). In ...

Reaction of Co(NCS)2 with 4-bromopyridine leads to the formation of discrete complexes with the composition Co(NCS)2(4-bromopyridine)4·(CH3CN)0.67 (1), Co(NCS)2(4-bromopyridine)2(H2O)2 (2), Co(NCS)2(4-bromopyridine)2(CH3OH)2 (3) and Co(NCS)2(4-bromopyridine)2(CH3CN)2 (4). Upon heating compounds 2 and 4 transform into a crystalline product with the composition Co(NCS)2(4-bromopyridine)2 (5-I) that also can easily be obtained from solution. In this compound, the Co cations are linked by single μ-1,3-bridging thiocyanate anions into layers. Thermal decomposition of 3 leads to a second isomer (5-II), which is thermodynamically metastable and can also be synthesized from solution under kinetic control. In contrast to 5-I, the Co cations are linked by pairs of anionic ligands into linear chains. The magnetic exchange is very weak in 5-I, but much stronger and ferromagnetic along the linear chains in 5-II. AF ordering in 5-II is reached at 3.05 K, and magnetic relaxation is observed at the metamagnetic transition with an Arrhenius barrier of 17.1(3) cm-1. Ab initio computational studies reveal a different type of magnetic anisotropy to be present in the two crystallographically - independent Co centers in 5-II.

The reaction of Ni(NCS)2 with 3-ethylpyridine in water leads to the formation of two known modifications of Ni(NCS)2(3-ethylpyridine)4 (1-I and 1-II) as well as of Ni(NCS)2(3-ethylpyridine)2(H2O)2 (2) that consist of discrete complexes. If the synthesis is performed in ethyl acetate, the new compound [Ni(NCS)2(3-ethylpyridine)2]n (3-lc) formed that comprises linear and corrugated Ni(NCS)2 chains in one crystal. By changing the solvent to dichloromethane, a solvate of compound 3 is obtained that consists exclusively of corrugated chains (3c-CH2Cl2). 3c-CH2Cl2 is unstable and transforms immediately into 3-lc. Upon heating the precursor complexes 1-I, 1-II and 2, the 3-ethylpyridine ligands are removed in two steps leading to a mixture of 3-lc and an additional isomer of 3 (3-l) in the first step that decomposes upon further heating into a compound with the composition [Ni(NCS)2(3-ethylpyridine)]n (4). Ex and in situ XRPD measurements reveal that a mixture of two modifications (4-I and 4-II) is always formed, preventing their structure determination by XRPD. Time dependent investigations in solution prove that 3-l is formed under kinetic control and transforms into 3-lc within several hours that is thermodynamically stable at room-temperature. Structure analysis of 3-l shows that in contrast to 3-lc and 3c-CH2Cl2 this isomer consists exclusively of linear Ni(NCS)2 chains. Magnetic measurements of the new chain compounds 3-l and 3-lc shows χT values that are typical for Ni(II) cations with S = 1. For 3-l the exchange constant was determined by fitting of the magnetic data leading to a value that is similar to that of [Ni(NSC)2(2,2′-bipyridine)2]n.

The cobalt(II) in [Co(NCS)2(4‐methoxypyridine)2]n are linked by pairs of thiocyanate anions into linear chains. In contrast to a previous structure determination, two crystallographically independent cobalt(II) centers have been found to be present. In the antiferromagnetic state, below the critical temperature (T c=3.94 K) and critical field (H c=290 Oe), slow relaxations of the ferromagnetic chains are observed. They originate mainly from defects in the magnetic structure, which has been elucidated by micromagnetic Monte Carlo simulations and ac measurements using pristine and defect samples. The energy barriers of the relaxations are Δτ1=44.9(5) K and Δτ2=26.0(7) K for long and short spin chains, respectively. The spin excitation energy, measured by using frequency‐domain EPR spectroscopy, is 19.1 cm−1 and shifts 0.1 cm−1 due to the magnetic ordering. Ab initio calculations revealed easy‐axis anisotropy for both CoII centers, and also an exchange anisotropy Jxx/Jzz of 0.21. The XXZ anisotropic Heisenberg model (solved by using the density renormalization matrix group technique) was used to reconcile the specific heat, susceptibility, and EPR data., Slowly relax… The magnetic properties of the linear chain compound [Co(NCS)2(4‐methoxypyridine)2]n have been investigated both experimentally and theoretically. Slow relaxations of the ferromagnetic chains were observed in the antiferromagnetic state and the specific heat, susceptibility, and EPR data obtained have been reconciled by using the XXZ anisotropic Heisenberg model (see figure).

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.

[Co(NCS)2(py)2]n (py = pyridine) is composed of ferromagnetic chains of Co(ii) cations connected by double NCS bridges. The chains are irregular because of two crystallographically inequivalent Co(ii) cations. The coordination polyhedron of the Co(ii) cations is a distorted octahedron built from two N and two S atoms of four equatorial NCS anions and two apical N atoms of the pyridine ligands. Magnetic and specific heat studies show that the compound undergoes a phase transition at 3.7 K to a ferromagnetic state. The determined magnetic interactions, intrachain (J/kB = 28 K) and interchain (zJ'/kB = 0.5 K), confirm the quasi 1D Ising magnetic character of [Co(NCS)2(py)2]n. Using AC magnetic susceptibility measurements the energy barriers for magnetization reversal of different relaxation processes were determined including those of the individual chains. By means of high field-high frequency ESR study the magnetic excitations were observed and explained in the frame of the Ising model in agreement with the results of the magnetic study. Ab initio calculations confirm the high magnetic anisotropy of the system and allow determination of the direction of the easy-axis. The broken symmetry DFT calculations support the ferromagnetic intrachain interactions. The energetic relations relevant for relaxations are discussed. It is concluded that the magnetic model of [Co(NCS)2(py)2]n is not a pure Ising but the transversal exchange plays a role.

Structure and solvatomagnetic properties of two 1D CN-bridged assemblies based on the [Mn(cyclam)]3+ complex (cyclam = 1,4,8,11-tetraazacyclotetradecane) have been characterised. The isostructural {[Mn(cyclam)][Cr(CN)6]·6H2O}n (1·6H2O) and {[Mn(cyclam)][Fe(CN)6]·6H2O}n (2·6H2O) chains crystallise in the space group C2/m. Dried in air at a slightly elevated temperature the hexahydrates undergo irreversible partial dehydration to stable dihydrates 1·2H2O and 2·2H2O, respectively. The structure model of 1·2H2O proposed from the PXRD data shows lower symmetry of the network described by the space group P21 and markedly different relative arrangement of the chains. The Mn-Cr chains are characterised by antiferromagnetic exchange through the CN-bridges (J = −2.8 K for 1·6H2O and −6.0 K for 1·2H2O), which was modelled using quantum Monte Carlo simulations. Together with weaker AF Mn-Cr interactions between the chains it leads to ferrimagnetic ordering. Ferromagnetic intra-chain interactions (J = 4.5 K for 2·6H2O and 7.1 K for 2·2H2O) and antiferromagnetic 3D ordering is observed for the Mn-Fe chains. The dehydration process in both compounds causes an increase in the strength of magnetic exchange, reflecting changes in the CN-bridge geometry.

The self-assembly of Dy(III) -3-hydroxypyridine (3-OHpy) complexes with hexacyanidocobaltate(III) anions in water produces cyanido-bridged {[Dy(III) (3-OHpy)2 (H2 O)4 ] [Co(III) (CN)6 ]}⋅H2 O (1) chains. They reveal a single-molecule magnet (SMM) behavior with a large zero direct current (dc) field energy barrier, ΔE=266(12) cm(-1) (≈385 K), originating from the single-ion property of eight-coordinated Dy(III) of an elongated dodecahedral geometry, which are embedded with diamagnetic [Co(III) (CN)6 ](3-) ions into zig-zag coordination chains. The SMM character is enhanced by the external dc magnetic field, which results in the ΔE of 320(23) cm(-1) (≈460 K) at Hdc =1 kOe, and the opening of a butterfly hysteresis loop below 6 K. Complex 1 exhibits white Dy(III) -based emission realized by energy transfer from Co(III) and 3-OHpy to Dy(III) . Low temperature emission spectra were correlated with SMM property giving the estimation of the zero field ΔE. 1 is a unique example of bifunctional magneto-luminescent material combining white emission and slow magnetic relaxation with a large energy barrier, both controlled by rich structural and electronic interplay between Dy(III) , 3-OHpy, and [Co(III) (CN)6 ](3-) .

A strategy to continuously tune the exchange constant J and the critical temperature Tc in the 1D coordination polymers [Co(NCS)x(NCSe)2−x(pyridine)2]n is reported. For such mixed crystals, prepared by annealing and from solution, an increase of J and Tc with increasing selenocyanate content is observed.

The quasi-one-dimensional [Co(NCS)2(pyridine)2]n coordination polymer built of ferromagnetic chains of Co(II) ions linked by (NCS)2 anions is known as an Ising ferromagnet that magnetically orders at TC = 3.9 K. We performed a neutron diffraction study and show that the magnetic structure is collinear ferromagnetic, static, and without any glassy component. The magnitude of the ordered magnetic moment of Co(II) is 3.65(15) μB, which points to a relatively large contribution of the orbital moment. The direction of the moment is close to the direction of the Co–N(pyridine) bond, which confirms literature ab initio calculations. We show that dipolar interactions are mainly responsible for the magnetic interchain coupling.

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.

An alternating bimetallic {(H3O)[Ni(III)(cyclam)][Fe(II)(CN)6]·5H2O}n chain undergoes reversible dehydration at 40 °C accompanied by electron transfer which leads to Ni(II)-Fe(III) in about 50% of metal centres. The hydrated dark blue form is a paramagnet while the dehydrated yellowish-green form shows ferromagnetic coupling between neighbouring Ni(II) and Fe(III).

A series of carbonato-bridged heteronuclear NiII2LnIII2 complexes 2[(μ4-CO3)2{NiLn(L)(MeOH)(CH3COO)}2]·9H2O·8MeOH (Ln = Tb (1), Dy (2), Ho (3), Er, (4)), [(μ4-CO3)2{NiLn(L)(MeOH)(CH3COO)}2]·2H2O·4MeOH (Ln = Tm (5)) and [(μ4-CO3)2{NiLn(L)(MeOH)(CH3COO)}2]·4MeOH (Ln = Yb (6), Lu(7)) with N,N′-bis(5-bromo-3-methoxysalicylidene)propylene-1,3-diamine (L) are reported. The complexes were obtained by a one-pot reaction with spontaneous fixation of atmospheric CO2 into the coordination species during crystallization process. In each complex the NiII2LnIII2 metal core has a similar topology. The hexadentate Schiff base ligands chelate the Ni(II) and Ln(III) ions forming two binuclear units, that are linked by two CO32− ions giving a carbonato bridged (μ4-CO3)2{NiIILnIII}2 structures. Ferromagnetic interactions between 3d–4f metal centers have been observed for compounds 1 and 2. In complexes 3–6 both the isotropic exchange as well as of thermal depopulation of mJ sublevels and magnetic anisotropy are observed. In compound 7, due to the nonmagnetic nature of the ground state of Lu(III) ions, only a weak antiferromagnetic interaction between Ni(II) ions occurs.

Three new coordination compounds with the composition Co(NCS)2(4-(3-phenylpropyl)pyridine)4 (1), Co(NCS)2(4-(3-phenylpropyl)pyridine)4(H2O)2 (2) and [Co(NCS)2(4-(3-phenylpropyl)pyridine)2]n (3) were prepared and investigated. The crystal structures of compounds 1 and 2 consist of discrete complexes, in which the Co(II) cations are coordinated by only terminal N-bonded thiocyanato anions. In the crystal structure of 3 the Co(II) cations are linked into chains by pairs of μ-1,3-bridging thiocyanato anions. DTA-TG measurements on compound 1 show decomposition without the formation of 3 as an intermediate. In contrast, on heating compound 2 two water molecules are removed in the first step leading to the formation of compound 3 in the second step. Magnetic measurements on 3 reveal ferromagnetic interactions between Co(II) ions along chains with J = 29.5(1) K, and also ferromagnetic interactions between chains with zJ′ = 0.38(1) K. The ferromagnetic transition is observed at 3.3 K, which is confirmed by specific heat measurements. The temperature dependent ac susceptibility shows slow relaxations above and below 3.3 K. The results for this quasi-one dimensional Ising ferromagnet, having also some features of a cluster spin-glass, are compared with those of related compounds.

Cyanido-bridged high-spin $\{Co^{II}[Co^{II}(MeOH)_{3}]_{8}[W^{V}(CN)_{8}]_{6}\} (Co_{9}W_{6})$ clusters revealing single-molecule magnet behavior were combined with 4,{4}'-bipyridine-N,N′-dioxide (4,{4}'-bpdo) linkers, giving unique H-bonded supramolecular $\{Co^{II}_{9}(MeOH)_{24}[W^{V}(CN)_{8}]_{6}\}\cdot 4,{4}'-bpdo \cdot MeOH \cdot 2H_{2}O$ (1) chains and one-dimensional coordination $\{Co^{II}[Co^{II}(4,{4}'-bpdo)_{1.5}(MeOH)]_{8}[W^{V}(CN)_{8}]_{6}\} \cdot 2H_{2}O$ (2) nanowires. The hydrogen-bonded chains of 1 are embedded within the three-dimensional supramolecular network stabilized by the series of noncovalent interactions between $Co_{9}W_{6}$ clusters, 4,{4}'-bpdo, and solvent molecules. The coordination nanowires 2, revealing an average core diameter of about 11 \AA , are arranged parallel with the significant separation in the crystal structure, leading to a microporous supramolecular network with broad channels (12 × 12 \AA) filled by methanol and water. Both 1 and 2 are stable only in a mother solution or an organic protectant, whereas they undergo the fast exchange of methanol ligands to water molecules during drying in the air. Synthesized materials preserve the magnetic characteristics of $Co_{9}W_{6}$ clusters with an effective ferromagnetic coupling, giving a ground-state spin of 15/2. For 2, the additional antiferromagnetic intercluster interactions are observed. Below 3 K, the frequency-dependent $\chi _{M}$ (T) signals of 1 and 2 indicate the onset of slow magnetic relaxation. For 1, the relaxation time follows the Arrhenius law with an energy gap of $\Delta / k_{B}= 10.3(5) K$ and $\tau _{0}= 4(1) \times 10^{-9} s$, which is consistent with single-molecule magnet behavior.

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.

Two high-spin pentanuclear NiW clusters with diimine blocking ligands have been obtained: {[Ni(4,4'-MeObpy)2]3[W(CN)8]2}·12H2O (1) and {[Ni(phen)2(H2O)][Ni(phen)2]2[W(CN)8]2}·7H2O (2) (4,4'-MeObpy = 4,4'-dimethoxy-2,2'-bipyridine, phen = 1,10-phenanthroline). Despite the similarity of the building blocks and synthetic conditions the compounds show different topologies of the cluster core: 1 is a trigonal bipyramid while 2 is a decorated square. Both cluster structures are chiral with either ΔΔΔ or ΛΛΛ configuration around all three Ni centres. In 1 spontaneous resolution occurs and it crystallises in the P212121 space group forming a conglomerate containing both types of enantiomorphic crystals. 1Δ and 1Λ are the first pair of enantiomorphic structures of cyano-bridged clusters of trigonal bipyramidal topology obtained with achiral bidentate blocking ligands. 2 crystallises as a racemic compound in a centrosymmetric space group P1[combining macron] with both enantiomers present in the structure. 2 is an exceptional square-motif containing structure with an identical stereoconfiguration of all complex cations within one cluster. Ferromagnetic interactions are present in both clusters resulting in the ground spin state S = 4.

The microwave-mediated self-assembly of [W(V)(CN)(8)](3-) with Cu(II) in the presence of pyrazole ligand resulted in the formation of three novel assemblies: Cu(II)(2)(Hpyr)(5)(H(2)O)[W(V)(CN)(8)](NO(3))·H(2)O (1), {Cu(II)(5)(Hpyr)(18)[W(V)(CN)(8)](4)}·[Cu(II)(Hpyr)(4)(H(2)O)(2)]·9H(2)O (2), and Cu(II)(4)(Hpyr)(10)(H(2)O)[W(V)(CN)(8)](2)(HCOO)(2)·4.5H(2)O (3) (Hpyr =1H-pyrazole). Single-crystal X-ray structure of 1 consists of cyanido-bridged 1-D chains of vertex-sharing squares topology. The structure of 2 reveals 2-D hybrid inorganic layer topology with large coordination spaces occupied by {Cu(Hpyr)(2)(H(2)O)(4)}(2+) ions. Compound 3 contains two types of cyanido-bridged 1-D chains of vertex-sharing squares linked together by formate ions in two directions forming hybrid inorganic-organic 3-D framework (I(1)O(2)). The magnetic measurements for 1-3 reveal a weak ferromagnetic coupling through Cu(II)-NC-W(V) bridges.

Using a polyamine cation tetrenH55+ (tetren = tetraethylenepentaamine), we tailored the dynamic layered material (tetrenH5)1.6{CoII(H2O)2[MIV(CN)8]}4·xH2O (1, M = W, x = 12; 2, M = Mo, x = 11.2). 1 and 2 consist of strongly corrugated two-dimensional (2D) cyano-bridged monolayers {CoII(H2O)2[MIV(CN)8]}n2n– of square grid topology stacked in an alternate manner with cationic layers of tetrenH55+ and H2O molecules. The observed single-crystal-to-single-crystal (SCSC) transformation is due to the reversible dehydration of 1 and 2 to the respective monocrystalline materials (tetrenH5)1.6{CoII[MIV(CN)8]}4 (1deh and 2deh). Structural modifications consist of the change of coordination number (C.N.) of Co(II) from 6 to 4 and a degree of corrugation of the coordination skeleton resulting in changes of orthorhombic cell dimensions. The exposition of 1deh to vapors of H2O, MeOH, HCONH2, and MeCN gives 1reh, 1deh·5.6MeOH, 1deh·4HCONH2, and 1deh·2.4MeCN phases, respectively. 1reh reveals structural, physical, and phy...

Incorporation of urea molecules into the magnetic system MnII-[NbIV(CN)8] results in formation of two magnetic polymorphs {[MnII(H2O)(urea)2]2[NbIV(CN)8]}n chiral α and centric β crystallizing in space groups P41 and P1, respectively. Both polymorphs exhibit extremely similar structures and are soft ferrimagnets with critical temperatures of 43 and 42 K, respectively. The presence of coordinated urea in the noncentrosymmetric α produces NLO functionality, second harmonic generation (SHG), whereas centric β is just another molecular magnet. As a result of interaction of both functionalities below magnetic ordering temperature, the magnetization-induced SHG (MSHG) is observed for polymorph α. The observed MSHG/SHG signal ratio was the largest among molecule-based noncentrosymmetric magnets. The presence of urea molecules in both polymorphs gives also rise to their interesting topotactic reactivity. Both polymorphs can be easily transformed into a new entity {[MnII(H2O)]2[NbIV(CN)8]·2.5MeOH}n 2b with signif...

Pentadecanuclear cyano-bridged high spin {MnII9WV6(CN)48(solv)24} clusters serve as bifunctional molecular building blocks in the construction of a {MnII9[WV(CN)8]6(dpe)5(MeOH)10}·14MeOH (dpe = trans-1,2-di(4-pyridyl)ethylene) organic−inorganic hybrid network of I1O2 topology. The intercluster connections are formed by Mn−NC−W and Mn−dpe−Mn linkages. The Mn−NC−W linkages lead to one-dimensional (1D) cyanido-bridged nanowires {Mn9W6}n with a van der Vaals diameter changing periodically from ∼1 to ∼1.5 A, with Mn−dpe−Mn linkages controlling the effective distances between them. The magnetic measurements suggest the superparamagnetic behavior of {Mn9W6}n skeletons below 100 K due to the internal ferrimagnetic ordering through CN− bridges. Below 3.5 K, weak antiferromagnetic interactions between the {Mn9W6}n operate, with two inflection points H1 = 100 Oe and H2 = 480 Oe observed in the M(H) curve at 1.8 K.

The reaction of cerium(III) nitrate, sodium octacyanotungstate(V), and 2,2'-bipyrimidine (bpm) under various conditions leads to the formation of three new compounds: ionic [Ce(2)(bpm)(dmf)(6)(H(2)O)(8)][W(CN)(8)](2).3H(2)O (1; dmf = N,N-dimethylformamide), tetranuclear molecules [Ce(2)(bpm)(dmso)(8)(H(2)O)(4)][W(CN)(8)](2).4H(2)O (2; dmso = dimethyl sulfoxide), and a two-dimensional inorganic-organic hybrid coordination polymer {[Ce(2)(bpm)(dmf)(8)(H(2)O)(2)][W(CN)(8)](2)}(n).2nH(2)O (3), all of which contain the subunit [Ce(2)(mu-bpm)] within the structure. These systems were characterized by single-crystal X-ray diffractometry, FTIR spectroscopy, and thermogravimetric analysis. Magnetic susceptibility measurements for 1-3 were performed on polycrystalline samples of the compounds. Magnetic behavior was interpreted in terms of the ligand-field splitting parameters and the exchange interaction between lanthanide centers and a d-electron spin carrier. The results confirmed the ferromagnetic cyano-mediated {Ce-NC-W} interaction J(CeW) = 1.7 (2) and 1.4(3) cm(-1) (3) compared to the antiferromagnetic {Ce-bpm-Ce} interaction J(CeCe) = -1.1 cm(-1) (1 and 2).

Pentadecanuclear high spin cyano-bridged {M' II 9 M" v 6 (CN)48(solv)24) (M' = 3d metal ions; M" = Mo, W; solv = H 2 O, alcohol) clusters are considered as building blocks for three-dimensional open networks. Self-assembly of Mn II 9 W v 6 clusters (S = 39/2) with 4,4'-bipyridine leads to their organization into an organic-inorganic hybrid coordination network {Mn II 9 (4,4'-bpy) 4 [W v (CN) 8 ] 6 (EtOH) 12 (H 2 O) 4 } ·10EtOH 1 (System, triclinic; space group: P1, a = 17.1569(2) A, b = 17.3835(2) A, c = 19.2530(2) A, a = 103.5520(10)°, P = 115.3950(10)°, y = 98.3060(10)°, Z = 1). The clusters are connected through 4,4'-bpy spacers into a two-dimensional square-grid coordination framework extended in the ab crystallographic plane with the smallest intercluster separation along the a (Mn···W = 7.12 A) and b (Mn···W = 7.15 A) directions significantly lower than that along the c crystallographic direction (Mn···W = 8.64 A). Direct current magnetic measurements suggest strong dominance of intracluster antiferromagnetic Mn II -W v coupling over a very weak intercluster antiferromagnetic interaction.

Two 1D CN-bridged coordination polymers based on the cyclam (cyclam = 1,4,8,11-tetraazacyclotetradecane) complex of nickel in an unusual oxidation state III have been characterised in terms of structure and solvatomagnetic properties. The {[Ni(cyclam)][Cr(CN)6]·6H2O}n (1) and {[Ni(cyclam)][Fe(CN)6]·6H2O}n (2) chains are isostructural and crystallise in space group C2/m. They undergo reversible partial dehydration at 40 °C to {[Ni(cyclam)][Cr(CN)6]·3H2O}n (1d) and {[Ni(cyclam)][Fe(CN)6]·3H2O}n (2d), accompanied by marked changes in structure and magnetic properties. Strong ferromagnetic exchange interaction J along the chains, together with a much weaker inter-chain interaction, leads to magnetic ordering in the range from 2.4 to 5.8 K. Dehydration of 1 leads to a decrease in J from 32 to 18 K, while dehydration of 2 leads to an increase in J from 6.8 to 14.3 K (interaction Hamiltonian −2JSNiSM). The magnetic susceptibility for the CrIII–NiIII 3/2–1/2 spin alternating Heisenberg chain was analysed with the help of quantum Monte Carlo simulations, simultaneously including both intra- and inter-chain interactions for a bunch of chains. The compounds are the first bimetallic CN-bridged assemblies containing a magnetically coupled octahedral cationic building block of an LS d7 configuration.

The self-assembly reaction between trivalent lanthanide ions, 2,2':6',2' '-terpyridine (terpy) ligand, and octacyanotungstate(V) leads to the formation of two series of isomorphous cyano-bridged compounds: (i) one-dimensional (1-D) chains [Ln(terpy)(DMF)(4)][W(CN)(8)].6H(2)O.C(2)H(5)OH (Ln = Ce-Dy) and (ii) dinuclear molecules [Ln(terpy)(DMF)(2)(H(2)O)(2)][W(CN)(8)].3H(2)O (Ln = Ho, Er, Yb) and the ionic [Tm(III)(terpy)(DMF)(2)(H(2)O)(3)][WV(CN)(8)].4H(2)O.DMF (DMF = N,N-dimethylformamide) system. The crystal structures of 1-D chains consist of alternating {[W(CN)(8)]} and {[Ln(terpy)]} building blocks. The neighboring chains are weakly linked through the pi-pi stacking interactions of the aromatic rings, leading to two-dimensional supramolecular layers. The dinuclear species are weakly linked through the hydrogen bonds between H2O molecules and terminal cyano ligands resulting in a columnlike arrangement of dimers. Taking into account the ligand-field splitting and the exchange interaction, we have estimated the magnetic couplings between the Ln(III) and WV centers in a series of polycrystalline 1-D chains and in dimeric systems. The corresponding exchange constants have been shown to change the sign along the series of chains. The coupling is antiferromagnetic for 1 (J = -0.24 cm(-1)) and 2 (J = -0.07 cm(-1)), whereas 3 (J = +0.47 cm(-1)), 7 (J = +0.28 cm(-1)), and 8 (J = +0.23 cm(-1)) have ferromagnetic character. In the case of dimeric systems, the coupling constants seem to be independent of the lanthanide center. The splitting structures of the ground-state multiplets of the Ln(III) centers have been shown to explain the temperature dependences of the magnetic susceptibilities.

Photomagnetic compounds are usually achieved by assembling preorganized individual molecules into rationally designed molecular architectures via the bottom-up approach. Here we show that a magnetic response to light can also be enforced in a nonphotomagnetic compound by applying mechanical stress. The nonphotomagnetic cyano-bridged Fe(II)-Nb(IV) coordination polymer {[Fe(II)(pyrazole)4]2[Nb(IV)(CN)8]·4H2O}n (FeNb) has been subjected to high-pressure structural, magnetic and photomagnetic studies at low temperature, which revealed a wide spectrum of pressure-related functionalities including the light-induced magnetization. The multifunctionality of FeNb is compared with a simple structural and magnetic pressure response of its analog {[Mn(II)(pyrazole)4]2[Nb(IV)(CN)8]·4H2O}n (MnNb). The FeNb coordination polymer is the first pressure-induced spin-crossover photomagnet.

International audience; Three isostructural 2D inorganic–organic hybrid MII–[MV(CN)8]3− materials with pyrazine (pyz) incorporated as a short organic linker between 3,2-chain motifs: [MII(pyz)(DMF)3]2[MII(DMF)4][MV(CN)8]2 (where MII/MV is Co/W in 1; Cu/W in 2; and Cu/Mo in 3), were constructed from the combinations formed in situ by MII–pyrazine (MII = Co, Cu) assemblies with cyanide building blocks [MV(CN)8]3− (MV = Mo, W). The unprecedented architecture of 1–3 reveals no crystallization solvent molecules and propagation of pyrazine bridges in a perpendicular direction, contrary to the previously reported compound [CuII(4,4′-bpy)(DMF)]2[CuII(4,4′-bpy)(DMF)2][WV(CN)8]2·2DMF·2H2O with 4,4′-bipyridine bridges. Magnetic studies of 1–3 reveal the presence of overall ferromagnetic interactions in the cyanido-bridged MII–WV pairs and weak antiferromagnetic interactions transferred through the MII–pyz–MII linkages.

A new crystalline pseudo-polymorphic form of the 2D microporous honeycomb-like magnetic network {[Ni(cyclam)]3[W(CN)8]2·solv}n was obtained from the reaction between methanol-soluble {Ni[Ni(MeOH)3]8[W(CN)8]6} clusters and the [Ni(cyclam)]2+ complex in an acetonitrile-rich solvent mixture. In comparison to the three earlier characterised pseudo-polymorphs, which all crystallised in the triclinic space group P[1 with combining macron], the new form shows higher symmetry of C2/m, greater porosity of ca. 40% solvent accessible volume, and the highest magnetic ordering temperature of 12 K. It undergoes an irreversible single-crystal-to-single-crystal transformation to the hexadecahydrate form that is stable in air at ambient temperature. A new synthetic pathway leading directly to methanol solvate of the same network, which was previously obtained by sorption of MeOH into the anhydrous form, is also reported.

The reaction of Co(NCS)2 with 4-(4-chlorobenzyl)pyridine (ClBP) leads to the formation of Co(NCS)2(4-(4-chlorobenzyl)pyridine)4 (1) and [Co(NCS)2(4-(4-chlorobenzyl)pyridine)2]n (2). In the crystal structure of 1 the Co(II) cations are octahedrally coordinated by two terminal bonded thiocyanato anions and four ClBP ligands, whereas in 2 the Co(II) cations are linked into chains by pairs of μ-1,3-bridging thiocyanato anions. Magnetic measurements of 2 show an antiferromagnetic phase transition with TN = 3.9 K. A metamagnetic transition is observed at the critical magnetic field of 260 Oe. Magnetic relaxations in the zero field are consistent with single chain magnetic behavior. These results are compared with those obtained for similar compounds reported recently.

Reaction of Co(NCS)2 with 1,2-bis(4-pyridyl)-ethane (bpa) leads to the formation of [Co(NCS)2(bpa)2]n, which, on heating, transforms into the new layered coordination polymer [Co(NCS)2(bpa)]n. This compound can also be prepared in solution, but because no reasonable single crystals are available, its crystal structure was determined from X-ray powder data from scratch. In the crystal structure of [Co(NCS)2(bpa)]n, the cobalt(II) cations are coordinated by two S-bonded and two N-bonded thiocyanato anions and two N atoms of the bpa co-ligands in a distorted octahedral geometry. The cobalt(II) cations are linked into chains by pairs of μ-1,3 bridging thiocyanato anions. These chains are further connected into layers by the 1,2-bis(4-pyridyl)-ethane ligand. The compound was magnetically characterized, and, for comparative purposes, the complementary magnetic study of a known and very similar compound, [Co(NCS)2(bpe)]n (bpe = 1,2-bis(4-pyridyl)-ethylene), was also undertaken. The compounds differ in their interchain interactions, which are antiferromagnetic but significantly greater for [Co(NCS)2(bpe)]n. Magnetic measurements indicate that [Co(NCS)2(bpa)]n is a canted antiferromagnet with Néel temperature TN = 3.1 K and that Co(NCS)2(bpe) is an antiferromagnet with TN = 4.0 K. Both compounds show a metamagnetic transition with a critical field HC ∼ 40 Oe and ∼ 400 Oe, respectively. Magnetic relaxations were studied by means of dc and ac methods and analyzed using the Argand diagrams. Except for the thermally activated single chain and domain wall relaxations observed for both compounds, temperature-independent slow relaxations were observed for [Co(NCS)2(bpa)]n.

Planar honeycomb-like coordination network {[Ni(cyclam)]3[W(CN)8]2}n (cyclam = 1,4,8,11-tetraazacyclotetradecane) was obtained in the self-assembly reaction of [Ni(cyclam)]2+ and [W(CN)]83-. Its structure is characterized by void channels along the a axis. The compound shows reversible water adsorption in the temperature range of 25-40 degrees C with the formation of {[Ni(cyclam)]3[W(CN)8]2}n.16nH2O, accompanied by single-crystal-to-single-crystal transformation. The structural transformation significantly changes the character of intraplane magnetic exchange interactions.

Pyrazine-N,{N}' -dioxide (pzdo) was used as a linker in the design and synthesis of hybrid octacyanometalate-based networks. Four new compounds $Na_{6}[W^{V}(CN)_{8}]_{2}(pzdo)_{7} \cdot 5H_{2}O$ (1), $K_{3}[W^{V}(CN)_{8}](pzdo)_{2} \cdot 4H_{2}O$ (2), ${Mn{_{6}}^{II}(pzdo)_{4}(MeOH)_{10}[W^{V}(CN)_{8}]_{4}} \cdot 4MeOH$ (3), and ${Mn{_{2}}^{II}(pzdo)(H_{2}O)_{4}[W^{IV}(CN)_{8}]} \cdot 4H_{2}O$ (4) reveal specific $M-pzdo-[W(CN)_{8}]^{3-/4-} (M = Na^{I}, K^{I}, Mn^{II})$ structural arrangements where pzdo plays a significant role. Apart from typical supramolecular interactions including hydrogen bonding and van der Waals interactions, the ${[M(\mu-pzdo)M][W(CN)_{8}]_{x}}$ (x = 1 or 2) structural motifs in 1–4 are organized by specific supramolecular interactions of the pzdo molecule and the octacyanotungstate anions: face-to-face sandwich type interactions between the plane of the pzdo aromatic ring and $N_{4}$ square face of $[W(CN)_{8}]^{n-}$ anions, edge-to-face interactions between the plane of the pyrazine ring and a pair of neighboring $N_{CN}$ atoms of the $[W(CN)_8]$-moiety, and end-to-face interactions between the plane of the pyrazine ring and a single $N_{CN}$ atoms of the $[W(CN)_{8}]$-moiety. The related intermolecular arrangements show features typical for anion−π interactions, unprecedented in the octacyanometalate chemistry. The specific interactions of the octacyanotungstate and the pzdo molecule in 1 and 2 lead to significant modification of their electronic spectra. Magnetic studies revealed that 1, 2, and 4 are paramagnetic, although 3 orders antiferromagnetically at $T_{C}$ = 17.5 K.

Reaction of Co(NCS)2 with 4-ethylpyridine leads to the formation of three new compounds of composition Co(NCS)2(4-ethylpyridine)4 (1), [(Co(NCS)2]2(4-ethylpyridine)6 (2), and [Co(NCS)2(4-ethylpyridine)2]n (3). In all compounds the coordination of the Co(II) ions is distorted octahedral. 1 consists of discrete monomeric complexes and in 2 two Co(II) cations are linked by pairs of μ-1,3-bridging thiocyanato ligands into dimers. In the crystal structure of 3 the Co(II) cations are connected into chains by the same bridge as in 2. Magnetic studies show that 1 and 2 are paramagnets down to a temperature of 2 K, while compound 3, which is the main object of this study, is an antiferromagnet with the Néel temperature T(N) = 3.4 K. Its magnetic structure is built from ferromagnetic chains, which are weakly antiferromagnetically coupled. With increasing magnetic field a metamagnetic transition starts at ~175 Oe, as observed for a polycrystalline sample. Magnetic relaxations, which were observed in the antiferromagnetic state, are retained at the metamagnetic transition. With decreasing field 3 remains in a state, in which except of the faster magnetic relaxation process in single chains also a slower process coexists resulting in the appearance of a magnetic hysteresis loop.

Mn(III) tetra(meta-fluorophenyl)porphyrin-tetracyanoethenide coordination polymer (abbreviated meta-F) was synthesized and crystallographically and magnetically characterized. The compound crystallizes in the space group C2/c with four equivalent molecules in the unit cell arranged along two symmetry related nonparallel linear chain directions. Magnetic properties were studied by SQUID dc magnetization and ac susceptibility techniques and high field-high frequency electron spin resonance (HF-ESR). Glassy transition to a ferromagnetic-like state is observed at 10 K accompanied by slow magnetic relaxations. The glassiness is interpreted as due to 3D domain wall pinning. In a bias dc magnetic field the width of the relaxation time distribution decreases and the relaxations become similar to the relaxations of the single chain magnet Mn(III) tetra(ortho-fluorophenyl)porphyrin-tetracyanoethenide (abbreviated ortho-F), for which comparative HF-ESR studies were also conducted in this work. Magnetic properties of these two compounds are compared, and the nature of magnetic relaxations in meta-F is discussed.

Crystals of (H3O){[Cu(dien)]4[W(CN)8]} [W(CN)8]2·6.5H2O (dien: diethylenetriamine) are prepared by slow diffusion of aqueous solutions of [Cu(dien)(H2O)2]Cl2 and Cs3[W(CN)8] in an H-tube at room temperature (pH 5.5, 22% yield).

We present the magneto-structural correlations for two novel discrete cyano-bridged assemblies based on cationic complexes of manganese(II) with diimine ligands and octacyanotungstate(V) ions. The crystal structure of [Mn II (terpy)(dmf)-(H 2 O) 2 ][Mn II (terpy)(H 2 O)(dmf)(μ-NC)W V (CN) 7 ] 2· 6H 2 O (1) (terpy = 2,2';6',2"-terpyridine, dmf = dimethylformamide) contains dinuclear {Mn II W V } - cyano-bridged anions, while the crystal structure of [Mn II (phen) 3 ] 2 [MnII(phen) 2 (μ-NC) 2 -W V (CN) 6 ] 2 (ClO 4 ) 2 ·9H 2 O (2) (phen = 1,10-phenanthroline) is built of tetranuclear {Mn II 2 W V 2} 2- square anions. Intramolecular Mn-W magnetic interactions through the cyano bridges are represented by magnetic coupling constants J = -39 cm -1 for the {Mn II W V }- unit in 1 and J 1 = -25.7 and J 2 = -16.7 cm -1 for the {Mn II 2 W V 2 } 2- unit in 2. J and J 1 represent relatively strong W-CN-Mn interactions and are ascribed to the bridges in b positions of TPRS-8 (trigonal prism square-face bicapped) of [W(CN) 8 ] 3- polyhedra, favoring the strongest electronic interactions between the d z2 -d x2-y2 orbital of W and the π* orbitals of CN - , whereas J 2 is related to the m vertex of [W(CN) 8 ] 3- . The magnetic properties of 1 and 2 are compared with reference compounds and discussed in the context of the type of coordination polyhedra of [W(CN) 8 ] 3- as well as the metric parameters of cyano-bridged W-CN-Mn linkages. We found the type of coordination polyhedra and bridging mode of [W(CN) 8 ] 3- to be the most important factors influencing the magnitude of the Mn-W magnetic interaction.

A series of heterobimetallic, cyano-bridged 3D inorganic-organic hybrid networks with MnII-L-MnII and MnII-NC-NbIV linkages are reported. Reaction of [Mn(H2O)6]2+ with [Nb(CN)8]4- in the presence of organic linker L (pyrazine (pyz), pyrazine-N,N'-dioxide (pzdo), and 2,2'-bipyrimidine (bpym)) in H2O affords {MnII2(pz)2(H2O)4[NbIV(CN)8]}.pz.3H2O (1), {MnII2(pzdo)(H2O)4[NbIV(CN)8]}.5H2O (2), and {MnII2(bpym)(H2O)2[NbIV(CN)8]} (3), respectively. 1-3 were examined by X-ray crystallography and vibrational and magnetochemical studies. 1 is characterized by the coexistence of 3D inorganic cyano-bridged and 1D organic [Mn-(micro-pyz)]n2n+ sublattices along with the presence of monocoordinated and crystallization molecules of pyrazine. Assemblies 2 and 3 exhibit dimeric {MnII2-(micro-L)}4+ coordination motifs. The magnetic behavior of heterobimetallic 1-3 complexes is dominated by antiferromagnetic coupling between MnII and NbIV centers mediated by cyano bridges, resulting in long-range ferrimagnetic ordering with a high TC of 27 (1), 37 (2), and 50 K (3). The magneto-structural correlation leads to the conclusion that the magnitude of TC is related to the type of coordination polyhedra of [Nb(CN)8] moieties (SAPR (1), intermediate between SAPR and DD (2), and DD (3)), the relative number of cyano bridges per Mn2Nb unit, and coexistence of inorganic and organic connectivity. FC/ZFC responses appear to be sensitive to the degree of organic connectivity. The discussion of magneto-structural correlation is based on the spin-density properties of adequate heterobimetallic systems containing octacyanometalates.

The synthesis, X-ray structure and magnetic properties of a new octacyanotungstate(V) based zero-dimensional [MnIII(3-OMesalophen)(H2O)2]2[MnIII(3-OMesalophen)(H2O)] [WV(CN)8] · 2H2O (1) system are reported. Compound 1 crystallizes in the triclinic system, has space group P 1 ¯ and unit cell dimensions a = 13.494(2) A, b = 17.080(4) A, c = 18.739(5) A with Z = 2. The structure of 1 consists of the dimeric Mn–NC–W cyano-bridged {[Mn(3-OMesalophen)(H2O)][W(CN)8]}2− anions and bis-μ-aqua-bridged dimers of [Mn(3-OMesalophen)(H2O)2]+ cations linked by H-bonds and π–π stacking into Mn 6 III W 2 V distinguishable structural and magnetic units. The magnetic behavior of 1 correspond to a dominant antiferromagnetic coupling within the cyano-bridged {MnIIIWV}2− dimer (J1 = −20 cm−1) and weaker AF coupling between hydrogen bonded moieties (J2 = −0.46 cm−1) with zero-field splitting D parameter of Mn(III) centre in axially distorted surroundings of −4.0 cm−1.

Reaction of the preorganized strands of ([Cu(II)(mu-4,4'-bpy)](2+))n (4,4'-bpy = 4,4'-bipyridine) with [W(V)(CN)(8)](3)(-) leads to a novel cyano-bridged Cu(II)(3)W(V)(2) complex [Cu(mu-4,4'-bpy)(DMF)(2)][Cu(mu-4,4'-bpy)(DMF)](2)[W(V)(CN)(8)](2).2DMF. 2H(2)O 1. The structure of 1 consists of the expected 2-dimensional grid-type network which is built of infinite ([Cu(II)(mu-4,4'-bpy)](2+))n chains cross-linked by octacyanotungstate units. The Cu(II)-NC-W(V)-CN-Cu(II) linkage exhibits the topology of a 3,2-chain. The skeleton of the layer is additionally stabilized by a hydrogen bond network formed by terminal cyano ligands of the [W(CN)(8)](3-) moiety and water molecules. The distance between the adjacent Cu(3)(II)W(2)(V) chains within the layer is 11.12 A along the a axis. The layers are connected by H-bonds of NCN-NDMF-NCN linkages into 3-D supramolecular architecture. The magnetic properties correspond to a dominant ferromagnetic coupling within the Cu(II)(3)W(V)(2) pentamer units (J = +35(4) cm(-1)) and much weaker effective AF interunit coupling which include both intra- and inter-3,2-chain interactions between pentamers (J' = -0.05(1) cm(-1)).

Molecular chains of antiferrimagnetically coupled MnIII-ion (S = 2) and TCNE (tetracyanoethylene) radical moments (s = ?) show different behaviour depending on group R substituted to TPP (tetraphenylporphyrin) and on the substitution site. The compound with R = F in Ortho position is a Single-Chain Magnet (SCM) with blocking temperature Tb = 6.6K, while that with R = F in Meta position shows both blocking (Tb = 5.4 K) and magnetic ordering transition (Tc = 10 K). For bulky groups R = OCnH2n+1, the magnetically ordered phase is observed (Tc ? 22 K), which does not however prevent slow relaxation at T