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Magnetic susceptibility, heat capacity, and neutron diffraction studies of Fe[C(CN)3]2 reveal the existence of two magnetic phase transitions at T(sub N,I) = 2.45 K and T(sub N,II) = 1.85 K. It was found that between 1.85 and 2.45 K, the magnetic ordering is incommensurate with a temperature-dependent propagation vector (k(sub I,x)0 0), k(sub I, x) = 0.525-0.540.

Quasielastic neutron scattering is used to probe the solid-state ligand dynamics in the coordination polymer Mn [N (CN)(sub 2)](sub 2)(pyz) {pyz = pyrazine} which has double-interpenetrating 3D lattices. The pyrazine ligand is seen to liberate in a deep potential in the low temperature monoclinic phase.

Research demonstrates a weak ferromagnetism below 42.5 K critical temperature for a three-dimensional manganese(II) azido complex in contrast to previous reports of their non-existence.

Research has been conducted on the Co (sub)2 {[N(CN) (sub)2] (sub)4 bpym} . H (sub)2 O and M{[N(CN) (sub)2 bpym} . H (sub)2 O (M = Mn, Fe, Co; bpym = 2,2'-bipyrimidine). The synthesis and structural characteristics of the compound are described.

Incorporation of the triangular mu(super 3) )[(C(CN)(sub 3)](sub -) ligand into polymeric arrays has led to a new class of spin-frustrated molecule-based magnets of the type M(super II)[(C(CN)(sub 3)](sub 2) (M = V, Cr). The crystal structure of Cr(super II)[(C(CN)(sub 3)](sub 2) (M = V, Cr) was determined from neutron powder diffraction at low temperature and was seen that it adopts an interpenetrating rutile-like topology.

(meso-Tetrakis(3,5-di-tert-butyl-4-hydroxyphenyl)porphinato)manganese(III) tetracyanoethenide, (MnTP'P)(TCNE), is a soluble molecule-based magnet made of trans-mu(sub 2)-bound (TCNE).- subunits. With interchain distances, the Curie temperature becomes unusually high. The magnetic susceptibility obeys the Curie-Weiss relation between 115 and 250 K. The (MnTP'P)(TCNE) polymer has short intrachain and long interchain Mn...Mn separations.

The synthesis, and structural and magnetic characterization of three [Cu.sup.2+]-containing coordination polymers, [Cu(H[F.sub.2])[(pyrazine).sub.2]]Sb[F.sub.6], [[Cu.sub.2]F(HF)(H[F.sub.2])[(pyrazine).sub.4]][(Sb[F.sub.6]).sub.2], and [CuAg([H.sub.3][F.sub.4])[(pyrazine).sub.5]][(Sb[F.sub.6]).sub.2] are presented. The polymers are found to crystallize in either tetragonal or orthorhombic space groups, have structures consisting of 2D square layers of [[M[(pyz).sub.2]].sup.n+] that are linked in the third dimension by either H[F.sub.2.sup.-] or [H.sub.3][F.sub.4.sup.-] and the variations observed in magnetic behaviors are driven by differences in the H***F hydrogen-bonding motifs.

X-ray powder diffraction and magnetic susceptibility measurements have shown that Ag[(pyz).sub.2]([S.sub.2][O.sub.8]) has 2-dimensional square nets of [Ag.sup.2+] ions resulting from the corner-sharing of axially elongated Ag[N.sub.4][O.sub.2] octahedral and have displayed characteristic 2D antiferromagnetism. [[mu].sup.+]SR measurements have shown that Ag[(pyz)([S.sub.2][O.sub.8]) has undergone 3D magnetic ordering below 7.8(3) K.

Tetraalkylammonium cations, (NR4)(super +) are used as templates to form a new family of [M(dca)3](super -)salts. The results indicate that tetrapropylammonium(super +) cations offer the promise of a closely related series with finely tunable sizes, leading to a better understanding of the templating effects.

A new three dimensional anionic structure Mn(dca)(sub 3)(super -) [dca=dicyanamide, N(CN)2(super -) is crystallized by using SPh(sub3)(super +) (ph = phenyl) cation as molecular template. Result shows that this salt exhibits a spin canted antiferromagnet below T(sub N)=2.5 K with H(super SF)=0.6 T.

Research has been conducted on coordination polymers containing Cu (super)2+ cations. The authors report magnetic and structural characterization of these polymers after their isolation.

Research has been conducted on green crystal of Cu(hfac) (sub)2 (tan), where hfac is hexafluoroacetylacetonate and tan is 1,4,5-triazanaphthalene. The structure of these compounds investigated at low temperature has demonstrated that it consists of kinked-chain arrangement.

Considerable attention is drawn towards the magnetic behavior of homo-(super 1-6) and heteroleptic (super 7) complexes with the dicyanamide ligand, [N(CN)(sub 2)](super -). The homoleptic complexes [Ph4P](sub 2){Co[N(CN)(sub 2)](sub 4)} and [Ph4P]{M[N(CN)(sub 2)](sub 3)} [M=Co, Mn] are structurally and magnetically characterized.

The study explains the formation of the tetrahedral cyanide complex in solution and the solid state. The social behavior of these complexes and the solids formed by their reactions are explained in the study.

The magnetic ordering with a relatively high Tc for the weak ferromagnets M(N(CN)2)2 was reported. Isostructural rutile-type frameworks were confirmed by powder X-ray diffraction and infrared spectroscopy with structurally characterized M(N(CN)2)2. Low magnetization values consistent with weak ferromagnetic behavior were observed for M = Cr and Mn. M = Cr showed an initial sharp rise in the magnetization to approximately 300 emuOe/mol at 3500 Oe and then became linear to 5 T reaching a substantially reduced value of 1000 emuOe/mol.

The buckled-layered structure of zinc dicyanamide ZnII(N(CN)2)2 was investigated. Zinc dicyanamide is the first structurally characterized tetrahedral metal dicyanamide complex and consists of an extended two-dimensional layered network in which each ZnII bonds to four (N(CN)2)- in a nearly ideal square Zn***Zn metal array and each (N(CN)2)- is micro-bonded to two ZnII centers. The synthesis and infrared spectrum of zinc dicyanamide were also described.

An analysis of the structure and magnetic properties of the (meso-tetraphenylporphinato)manganese(III) pentacyanopropenide compound was presented. The compound was characterized through the use of spectroscopic, crystallographic and magnetic approaches. Results showed that the lack of magnetic coupling and ordering for [MnIIITPP]+[C3(CN)5]- but presence of strong coupling and ordering for the [Mn(porphyrin)]+[TCNE]- family stresses the needs to have Mn(porphyrinate) bridged by spin-bearing ligands.

MnCl2(urea)2 is a new linear chain coordination polymer that exhibits slightly counter-rotated Mn2Cl2 rhomboids along the chain-axis. The material crystallizes in the noncentrosymmetric orthorhombic space group Iba2, with each Mn(II) ion equatorially surrounded by four Cl- that lead to bibridged ribbons. Urea ligands coordinate via O atoms in the axial positions. Hydrogen bonds of the Cl···H-N and O···H-N type link the chains into a quasi-3D network. Magnetic susceptibility data reveal a broad maximum at 9 K that is consistent with short-range magnetic order. Pulsed-field magnetization measurements conducted at 0.6 K show that a fully polarized magnetic state is achieved at Bsat = 19.6 T with another field-induced phase transition occurring at 2.8 T. Zero-field neutron diffraction studies made on a powdered sample of MnCl2(urea)2 reveal that long-range magnetic order occurs below TN = 3.2(1) K. Additional Bragg peaks due to antiferromagnetic (AFM) ordering can be indexed according to the Ib′a2′ magnetic space group and propagation vector τ = [0, 0, 0]. Rietveld profile analysis of these data revealed a Néel-type collinear ordering of Mn(II) ions with an ordered magnetic moment of 4.06(6) μB (5 μB is expected for isotropic S = 5/2) oriented along the b-axis, i.e., perpendicular to the chain-axis that runs along the c-direction. Owing to the potential for spatial exchange anisotropy and the pitfalls in modeling bulk magnetic data, we analyzed inelastic neutron scattering data to retrieve the exchange constants: Jc = 2.22 K (intrachain), Ja = −0.10 K (interchain), and D = −0.14 K with J > 0 assigned to AFM coupling. This J configuration is most unusual and contrasts the more commonly observed AFM interchain coupling of 1D chains. [ABSTRACT FROM AUTHOR]

Detailed research into the magnetic properties of Mn[N(CN)2]2(pyz) {pyz=pyrazine} is presented.

Layered crystalline materials were designed using coordination chemistry and hydrogen bonds.

[Ni(HF2)(3-Clpy)4]BF4 (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN4F2 octahedra that form chains with bridging HF2- ligands. In spite of significant distortion of the HF2- bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with JFHF = 4.86 K. [ABSTRACT FROM AUTHOR]

[Ni(HF2)(pyz)2]X {pyz = pyrazine; X = PF6- (1), SbF6- (2)} were structurally characterized by synchrotron X-ray powder diffraction and found to possess axially compressed NiN4F2 octahedra. At 298 K, 1 is monoclinic (C2/c) with unit cell parameters, a = 9.9481(3), b = 9.9421(3), c = 12.5953(4) Å, and β = 81.610(3)° while 2 is tetragonal (P4/nmm) with a = b = 9.9359(3) and c = 6.4471(2) Å and is isomorphic with the Cu-analogue. Infinite one-dimensional (1D) Ni-FHF-Ni chains propagate along the c-axis which are linked via μ-pyz bridges in the ab-plane to afford three-dimensional polymeric frameworks with PF6- and SbF6- counterions occupying the interior sites. A major difference between 1 and 2 is that the Ni-F-H bonds are bent (157°) in 1 but are linear in 2. Ligand field calculations (LFT) based on an angular overlap model (AOM), with comparison to the electronic absorption spectra, indicate greater π-donation of the HF2- ligand in 1 owing to the bent Ni-F-H bonds. Magnetic susceptibility data for 1 and 2 exhibit broad maxima at 7.4 and 15 K, respectively, and λ-like peaks in dχT/dT at 6.2 and 12.2 K that are ascribed to transitions to long-range antiferromagnetic order (TN). Muon-spin relaxation and specific heat studies confirm these TN's. A comparative analysis of χ vs T to various 1D Heisenberg/Ising models suggests moderate antiferromagnetic interactions, with the primary interaction strength determined to be 3.05/3.42 K (1) and 5.65/6.37 K (2). However, high critical fields of 19 and 37.4 T obtained from low temperature pulsed-field magnetization data indicate that a single exchange constant (J1D) alone is insufficient to explain the data and that residual terms in the spin Hamiltonian, which could include interchain magnetic couplings (J), as mediated by Ni-pyz-Ni, and single-ion anisotropy (D), must be considered. While it is difficult to draw absolute conclusions regarding the magnitude (and sign) of J and D based solely on powder data, further support offered by related Ni(II)-pyz compounds and our LFT and density-functional theory (DFT) results lead us to a consistent quasi-1D magnetic description for 1 and 2. [ABSTRACT FROM AUTHOR]

Three Cu2+-containing coordination polymers were synthesized and characterized by experimental (X-ray diffraction, magnetic susceptibility, pulsed-field magnetization, heat capacity, and muon-spin relaxation) and electronic structure studies (quantum Monte Carlo simulations and density functional theory calculations). [Cu(HF2)(pyz)2]SbF6 (pyz = pyrazine) (1a), [Cu2F(HF)(HF2)(pyz)4](SbF6)2 (1b), and [CuAg(H3F4)(pyz)5](SbF6)2 (2) crystallize in either tetragonal or orthorhombic space groups; their stwctures consist of 2D square layers of [M(pyz)2]n+ that are linked in the third dimension by either HF2- (1a and 1b) or H3F4- (2). The resulting 3D frameworks contain charge-balancing SbF6- anions in every void. Compound lb is a defective polymorph of 1a, with the difference being that 50% of the HF2- links are broken in the former, which leads to a cooperative Jahn-Teller distortion and dx²-y² orbital ordering. Magnetic data for 1a and 1b reveal broad maxima in χ at 12.5 and 2.6 K and long-range magnetic order below 4.3 and 1.7 K, respectively, while 2 displays negligible spin interactions owing to long and disrupted superexchange pathways. The isothermal magnetization, M(B), for 1a and 1b measured at 0.5 K reveals contrasting behaviors: la exhibits a concave shape as B increases to a saturation field, Bc, of 37.6 T, whereas 1b presents an unusual two-step saturation in which M(B) is convex until it reaches a step near 10.8 T and then becomes concave until saturation is reached at 15.8 T. The step occurs at two-thirds of Msat, suggesting the presence of a ferrimagnetic structure. Compound 2 shows unusual hysteresis in M(B) at low temperature, although χ vs T does not reveal the presence of a magnetic phase transition. Quantum Monte Carlo simulations based on an anisotropic cubic lattice were applied to the magnetic data of la to afford g= 2.14, J= -13.4 K(Cu-pyz-Cu), and J⊥ = -0.20 K(Cu-F⋯:H⋯:F-Cu), while χ vs T for 1b could be well reproduced by a spin-1/2 Heisenberg uniform chain model for g = 2.127(1), J1 = -3.81(1), and zJ2 = -0.48(1) K, where J1 and J2 are the intra- and interchain exchange couplings, respectively, which considers the number of magnetic nearest-neighbors (z). The M(B) data for 1b could not be satisfactorily explained by the chain model, suggesting a more complex magnetic structure in the ordered state and the need for additional terms in the spin Hamiltonian. The observed variation in magnetic behaviors is driven by differences in the H⋯F hydrogen-bonding motifs. [ABSTRACT FROM AUTHOR]

The structural, electronic, and magnetic properties of the new linear chain coordination polymer CuF2(H2O)2(pyz) (pyz = pyrazine) were determined by single crystal X-ray diffraction at various temperatures, SQUID magnetometry, pulsed-field magnetization, ESR, muon-spin relaxation (μSR), and electronic structure calculations. Each Cu2+ ion of CuF2(H2O)2(pyz) is located at a distorted CuF2O2N2 octahedron with axial elongation along the Cu−N bonds. These octahedra are tethered together by strong F···H−O hydrogen bonds to yield two-dimensional (2D) square nets in the bc-plane that are linked along the a-direction by pyrazine linkages. Measurements of the g-factor by ESR along with first principles density functional theory electronic structure calculations show that the magnetic orbital of the Cu2+ ion lies in the CuF2O2 plane thus forming a 2D antiferromagnetic square lattice. A broad maximum observed in χ(T) at 10 K indicates a modest spin exchange interaction through the Cu−F···H−O−Cu supersuperexchange paths, and a theoretical fit of χ(T) to a 2D square model gives J2D/kB = −5.58(1) K (in the convention where J rather than 2J is used for spin exchange). At lower temperatures, χ(T) shows a sharp peak at ∼2.6 K, which signals a transition to a long-range magnetic ordering as confirmed by coherent precession of implanted muons. Isothermal M(B) measurements made at 0.5 K on an aligned single crystal reveal magnetic saturation, Msat, at 28.8 T (B∥a) while a higher field of 33.1 T is required to saturate the spins when B is applied perpendicular to the a-axis thus showing clear anisotropy in these orientations. The presence of strong hydrogen bonds in CuF2(H2O)2(pyz) causes the chains to adopt a tilted packing arrangement, thus leading to a novel ground-state likely characterized by spin-canting within the 2D layers and a markedly increased critical temperature relative to the well-known Cu(NO3)2(pyz) polymer chain compound. In CuF2(H2O)2(pyz) the distorted CuF2(H2O)2(pyz)2 octahedral complexes are tethered together by strong F···H−O hydrogen bonds to form two-dimensional square lattices, which are linked in the third direction by pyrazine linkages. The magnetic orbital of each Cu2+ ion lies in the CuF2O2 plane so that the supersuperexchange interactions take place through the Cu−F · · · HO−Cu hydrogen bonded paths, and the magnetic properties of CuF2(H2O)2(pyz) are described by a 2D antiferromagnetic square lattice. [ABSTRACT FROM AUTHOR]

When stoichiometric amounts of Cu(hfac)[sub 2]·H[sub 2]O and 1,4,5-triazanaphthalene (tan) were combined in methanol, green crystals of Cu(hfac)[sub 2](tan) were formed. Its structure was determined at low temperature (P2[sub 1]/c; a = 8.3308(4) Å, b = 14.8945(7) Å, c = 18.3046(10) Å β = 99.298(2)°, V= 2241.5(3) ų) and found to consist of a novel kinked-chain arrangement where N atoms on opposite sides of the tan ligand bridge Cu(hfac)[sub 2] moieties together. Long axial Cu-N bonds lead to rather weak (J/k[sub B] = -0.06(5) K) antiferromagnetic interactions according to a Bonner-Fisher fit of the magnetic susceptibility data. The magnetic behavior demonstrated by Cu(hfac)[sub 2](tan) contrasts markedly with that of Cu(NO[sub 3])[sub 2](tan), as reported by Hatfield and co-workers, and is attributed to the differing orientations of the Cu d[sub x²-y²] magnetic orbital. [ABSTRACT FROM AUTHOR]

We have used quasielastic neutron scattering to probe the solid-state ligand dynamics in the coordination polymer Mn[N(CN)[SUB2]][SUB2](pyz) {pyz = pyrazine} which has double-interpenetrating 3D lattices. A reversible structural phase transition occurs at 410 K as shown by neutron spectroscopy and differential scanning calorimetry. The origin of this transition is linked to rotational dynamics associated with the bridging pyz ligands. At 425 K, the pyrazine ring motion can be solely regarded as a 180° reorientational jump about the axis defined by the Mn-N coordinative bonds, occurring with a correlation time of ~70 ps. This model can be extended to the 200-410 K temperature region using high-resolution backscattering spectroscopy to measure an identical motion on the time scale of nanoseconds with an activation energy of 24 ± 2 kJ mol[SUP-1]. In contrast, no quasielastic scattering is seen for the 2D layered variant β-Cu[N(CN)[SUB2]][SUB2]-(pyz), owing to its more compact layer packing motif. Importantly, this work represents the very first study of solid-state rotational dynamics in an interpenetrating lattice structure. [ABSTRACT FROM AUTHOR]

Investigates tetracyanomanganate(II) and its salts of divalent first-row transition metal ions. Monitoring of the photolysis; Observed rate of photoinduced decomposition.

Examines the long-range magnetic properties of Magnesium [N(CN)[sub 2]] [sub 2](pyz) {pyz = pyrazine}. Use of direct current magnetization, alternating current susceptibility, specific heat and neutron diffraction measurements; Properties of the crystallographic and antiferromagnetic structures; Evidence of spin-flop to paramagnetic transition in magnesium ion.

Examines the magnetic properties of a three-dimensional manganese(II) azido complex. Relevance of the crystal structure with magnetic behavior; Conditions influencing weak ferromagnetism of the complex; Application of low-field magnetization in the study.

Investigates the crystal and magnetic structure of the coordination solid Cr(II)[C(CN3)] by Rietveld refinement of the neutron diffraction data. Susceptibility measurements reveal strong antiferromagnetic interactions for both V- and Cr[C(CN3)] with theta=-67 and -46K; Bragg reflections as a result to antiferromagnetic ordering with the moments on the Cr(II) atoms.

Square-planar S = 1/2 AgII ions in polymeric Ag(nic)2 are linked by bridging nic monoanions to yield 2D corrugated sheets. Long-range magnetic order occurs below TN = 11.8(2) K due to interlayer couplings that are estimated to be about 30 times weaker than the intralayer exchange interaction. [ABSTRACT FROM AUTHOR]

Through use of the SPh3+ (Ph = phenyl, C6H5) cation as a molecular template, a new three-dimensional Mn(dca)3- [dca = dicyanamide, N(CN)2-] anionic structure has been crystallized. At room temperature, (SPh3)Mn(dca)3 (1) crystallizes in the monoclinic space group P21/c, with a -- 11.7079(5) Å, b = 12.8554(5) Å, c = 16.8605(6) Å, β -- 100.666(2)°, and V= 2493.8(3) ų. Magnetic susceptibility measurements indicate that this salt exhibits a spin canted long range antiferromagnetically ordered ground state below 2.5 K. [ABSTRACT FROM AUTHOR]

The article discusses a study that examined the antiferromagnetism in Ag(pyz)2(S2O8)(pyz = pyrazine)4. Results have shown that the compound consists of two-dimensional (2D) square nets of Ag2+ ions, which resulted from the corner-sharing of axially elongated AgN4O2 octahedra. It indicate that the bridging S2O82- ligands mediates weak interlayer spin exchange interactions.

Explores the spontaneous magnetization in weak ferromagnets in the form of M[N(CN)2]2, where M is chromium or manganese. Magnetic ordering of weak ferromagnets; Incomplete cancellation of spins in single-ion anisotropy and antisymmetric exchange; Crystal field effects; Stabilization of weak ferromagnets.

The Heisenberg antiferromagnetic chain is a canonical model for understanding many-body gaps that emerge in quantum magnets, and as a result, there has been significant work on this class of materials for much of the past century. Chiral chains, on the other hand, have received markedly less attention. [Cu(pym)(H 2 O) 4 ]SiF 6 ·H 2 O (pym = pyrimidine) is an S = 1/2 chiral antiferromagnet with an unconventional spin gap and no long-range ordering at zero field, features that distinguish it from more conventional spin chains that host simple phase diagrams and no magnetoelectric coupling. Here, we report pulsed magnetic field electrical polarization measurements, strong magnetoelectric coupling, and extraordinary magnetic field - temperature phase diagrams for this system. In addition to three low field transitions, we find a series of phase transitions between 40 and 70 T that depend on the magnetic field direction. The observation of electric polarization in a material with a nonpolar crystal structure implies symmetry-breaking magnetic ordering that creates a polar axis - a mechanism that we discuss in terms of significant interactions between the chiral chains as well as Dzyaloshinskii-Moriya effects. Further, we find second-order magnetoelectric coupling, allowing us to deduce the magnetic point group of the highest polarization phase. These findings are in contrast to expectations for an unordered one-dimensional spin chain and reveal a significantly greater complexity of behavior in applied field.

We present the magnetic properties of a new family of S = 1 molecule-based magnets, NiF 2 (3,5-lut) 4 ·2H 2 O and NiX 2 (3,5-lut) 4 , where X = HF 2 , Cl, Br, or I (lut = lutidine C 7 H 9 N). Upon creation of isolated Ni-X···X-Ni and Ni-F-H-F···F-H-F-Ni chains separated by bulky and nonbridging lutidine ligands, the effect that halogen substitution has on the magnetic properties of transition-metal-ion complexes can be investigated directly and in isolation from competing processes such as Jahn-Teller distortions. We find that substitution of the larger halide ions turns on increasingly strong antiferromagnetic interactions between adjacent Ni 2+ ions via a novel through-space two-halide exchange. In this process, the X···X bond lengths in the Br and I materials are more than double the van der Waals radius of X yet can still mediate significant magnetic interactions. We also find that a simple model based on elongation/compression of the Ni 2+ octahedra cannot explain the observed single-ion anisotropy in mixed-ligand compounds. We offer an alternative that takes into account the difference in the electronegativity of axial and equatorial ligands.

Magnetoelastic coupling in the quantum magnet [Ni(HF 2 )(pyrazine) 2 ]SbF 6 has been investigated via vibrational spectroscopy using temperature, magnetic field, and pressure as tuning parameters. While pyrazine is known to be a malleable magnetic superexchange ligand, we find that HF 2 - is surprisingly sensitive to external stimuli and is actively involved in both the magnetic quantum phase transition and the series of pressure-induced structural distortions. The amplified spin-lattice interactions involving the bifluoride ligand can be understood in terms of the relative importance of the intra- and interplanar magnetic energy scales.

The crystal structures of NiX2(pyz)2 (X = Cl (1), Br (2), I (3), and NCS (4)) were determined by synchrotron X-ray powder diffraction. All four compounds consist of two-dimensional (2D) square arrays self-assembled from octahedral NiN4X2 units that are bridged by pyz ligands. The 2D layered motifs displayed by 1-4 are relevant to bifluoride-bridged [Ni(HF2)(pyz)2]EF6 (E = P, Sb), which also possess the same 2D layers. In contrast, terminal X ligands occupy axial positions in 1-4 and cause a staggered packing of adjacent layers. Long-range antiferromagnetic (AFM) order occurs below 1.5 (Cl), 1.9 (Br and NCS), and 2.5 K (I) as determined by heat capacity and muon-spin relaxation. The single-ion anisotropy and g factor of 2, 3, and 4 were measured by electron-spin resonance with no evidence for zero-field splitting (ZFS) being observed. The magnetism of 1-4 spans the spectrum from quasi-two-dimensional (2D) to three-dimensional (3D) antiferromagnetism. Nearly identical results and thermodynamic features were obtained for 2 and 4 as shown by pulsed-field magnetization, magnetic susceptibility, as well as their Néel temperatures. Magnetization curves for 2 and 4 calculated by quantum Monte Carlo simulation also show excellent agreement with the pulsed-field data. Compound 3 is characterized as a 3D AFM with the interlayer interaction (J⊥) being slightly stronger than the intralayer interaction along Ni-pyz-Ni segments (J(pyz)) within the two-dimensional [Ni(pyz)2](2+) square planes. Regardless of X, J(pyz) is similar for the four compounds and is roughly 1 K.

We combined synchrotron-based infrared spectroscopy, Raman scattering, and diamond anvil cell techniques with complementary lattice dynamics calculations to reveal local lattice distortions in Mn[N(CN)2]2 under compression. Strikingly, we found a series of transitions involving octahedral counter-rotations, changes in the local Mn environment, and deformations of the superexchange pathway. In addition to reinforcing magnetic property trends, these pressure-induced local lattice distortions may provide an avenue for the development of new functionalities.

MnCl2(urea)2 is a new linear chain coordination polymer that exhibits slightly counter-rotated Mn2Cl2 rhomboids along the chain-axis. The material crystallizes in the noncentrosymmetric orthorhombic space group Iba2, with each Mn(II) ion equatorially surrounded by four Cl(-) that lead to bibridged ribbons. Urea ligands coordinate via O atoms in the axial positions. Hydrogen bonds of the Cl···H-N and O···H-N type link the chains into a quasi-3D network. Magnetic susceptibility data reveal a broad maximum at 9 K that is consistent with short-range magnetic order. Pulsed-field magnetization measurements conducted at 0.6 K show that a fully polarized magnetic state is achieved at Bsat = 19.6 T with another field-induced phase transition occurring at 2.8 T. Zero-field neutron diffraction studies made on a powdered sample of MnCl2(urea)2 reveal that long-range magnetic order occurs below TN = 3.2(1) K. Additional Bragg peaks due to antiferromagnetic (AFM) ordering can be indexed according to the Ib'a2' magnetic space group and propagation vector τ = [0, 0, 0]. Rietveld profile analysis of these data revealed a Néel-type collinear ordering of Mn(II) ions with an ordered magnetic moment of 4.06(6) μB (5 μB is expected for isotropic S = (5)/2) oriented along the b-axis, i.e., perpendicular to the chain-axis that runs along the c-direction. Owing to the potential for spatial exchange anisotropy and the pitfalls in modeling bulk magnetic data, we analyzed inelastic neutron scattering data to retrieve the exchange constants: Jc = 2.22 K (intrachain), Ja = -0.10 K (interchain), and D = -0.14 K with J > 0 assigned to AFM coupling. This J configuration is most unusual and contrasts the more commonly observed AFM interchain coupling of 1D chains.

[Ni(HF(2))(3-Clpy)(4)]BF(4) (py = pyridine) is a simple one-dimensional (1D) coordination polymer composed of compressed NiN(4)F(2) octahedra that form chains with bridging HF(2)(-) ligands. In spite of significant distortion of the HF(2)(-) bridge, a quasi-1D antiferromagnetic (AFM) behavior was observed with J(FHF) = 4.86 K.