Superexchange Paths Research Articles

Synthesis and magnetic properties of Co–Ti–Bi codoped M-type barium ferrite

The effects of Co2+, Ti4+, and Bi3+ substitution on the microstructures and properties of low-temperature fired M-type barium hexaferrites have been studied in order to adapt the development of low-temperature cofired ferrites technology and produce gyromagnetic devices with a multilayer process. It is found that Bi3+ ions can enter into the 2a sublattice and consequently enhance the grain growth and densification due to the activation of the lattice, which in turn first lead to an increase and then a decrease of Ms. The substitution of Bi3+ ions is beneficial to forming the M phase and lowers the sintering temperature to about 900 °C, which is ideal for cofiring with silver paste. Scanning electron microscope and x-ray diffraction analysis have shown that the samples have excellent crystalline grains with a uniform size about 1–2 μm. Moreover, nonmagnetic Ti4+ ions prefer to enter the 4fVI octahedral sites, giving rise to the weakening of the strong 12k-4fVI superexchange path and thus the isotropic exchange energy approaches the other second-order terms on the magnetic Hamiltonian, such as the antisymmetric interaction or even the magnetocrystalline anisotropy. With increasing the substitution content, some Co2+ ions, which locate in octahedral 12k sites, give a strong planar contribution to the anisotropy. Therefore, Ms and Hc decrease with the Co–Ti-substitution.

Synthesis, Characterization, and Quantum-Chemical Studies of Ni(CN)2MX (M = Rb, Cs; X = Cl, Br)

A new series of coordination-network compounds containing Ni(CN)(2) and MX (M = Rb, Cs; X = Cl, Br) quasi two-dimensional sheets has been synthesized and structurally characterized. The tetragonal crystal structure (I4/mmm, no. 139) can be derived from the distorted perovskite type. Chemically, the Lewis-acidic Ni(CN)(2) moieties accept halide ligands, resulting both in slightly elongated [Ni(NC)(4)X(2)](4-) octahedra and strongly elongated [Ni(CN)(4)X(2)](4-) octahedra that are charge-balanced by M(+) cations. Quantum-chemical calculations of the effective Hamiltonian crystal field (EHCF) type indicate the simultaneous presence of high- and low-spin Ni(2+) in a 1:1 ratio, in agreement with GGA+U and UV studies reported here. Our magnetic susceptibility data also corroborate the theoretical findings. An analysis of the magnetic superexchange paths in the new series of compounds is performed as well as that of the tentative magnetic state of the series.

Crystal Growth and Structure and Magnetic Properties of the 5d Oxide Ca3LiOsO6: Extended Superexchange Magnetic Interaction in Oxide

Crystals of the newly synthesized compound Ca(3)LiOsO(6) were grown by a flux method using LiCl and KCl, followed by single-crystal X-ray diffraction (XRD), low-temperature powder XRD, and measurements of ac and dc magnetic susceptibility and specific heat. The data indicate that Ca(3)LiOsO(6) has a fully opened electronic gap with an antiferromagnetic ordered state, consistent with suggestions from the first-principles study. The observed magnetic transition temperature is 117 K, too high to be caused only by a direct spin-spin interaction. It appears that the original superexchange magnetic path Os-O-Os is absent; thus, the extended superexchange path (Os-O)-(O-Os) can be expected to be responsible for the 117 K magnetic order. If this is true, Ca(3)LiOsO(6) would be highly valuable to study the nature of extended superexchange magnetic interactions in solids.

Unprecedented Layered Inorganic−Organic Hybrid Compound Mn3Sb2S6(C6H18N4) Composed of Mn4Sb2S6 Double-Cubane Units Showing Magnetic Long-Range Order and Frustration

The title compound Mn(3)Sb(2)S(6)(C(6)H(18)N(4)) (C(6)H(18)N(4) = triethylenetetramine) was obtained under solvothermal conditions by reacting Mn, Sb, S, and the amine at 140 degrees C for 7 days. The compound crystallizes in the triclinic space group P1 with a = 6.645(1) A, b = 8.667(1) A, c = 9.660(1) A, alpha = 90.82(2) degrees , beta = 109.70(2) degrees , gamma = 110.68(2) degrees , Z = 1, and V = 484.4(1) A(3). The Mn(4)Sb(2)S(6) double-heterocubane unit is the main motif in the structure of the title compound, which results from the interconnection of two SbS(3) trigonal pyramids, two MnS(6) octahedra, and two MnS(4)N(2) octahedra. The two N atoms completing the environment of the latter Mn(2+) ions belong to the tetradentate amine; i.e., the amine acts in a bidentate manner. The Mn(4)Sb(2)S(6) groups are joined by corner sharing of the MnS(6) octahedra, yielding one-dimensional linear Mn(3)Sb(2)S(6) rods along [100]. The two other N atoms of the amine molecule act in a bidentate manner to Mn(2+) ions of neighboring rods, thus producing layers within the (010) plane. Within the rods, the arrangement of the Mn(2+) ions in triangles leads to a chain of Mn(2+) diamonds connected via opposite corners. For the magnetic properties, each edge connecting the Mn(2+) ions represents a superexchange path due to coupling of the Mn(2+) centers via S bridges. The resulting Mn(2+) triangles give rise to substantial competing interaction and magnetic frustration. Below about 100 K, a gradual buildup of short-range antiferromagnetic correlations is observed. At lower temperatures, long-range antiferromagnetic interactions occur with T(N) = 2.90 K, as indicated by a lambda-type anomaly in the heat capacity curve. The analysis of the magnetic and heat capacity data evidences that the magnetic properties are essentially determined by the one-dimensional character of the Mn(3)Sb(2)S(6) chain. In addition, significant magnetic frustration due to the arrangement of the Mn(2+) ions in a triangular configuration cannot be neglected.

Magnetic structure and analysis of the exchange interactions inBiMO(PO4) (M = Co, Ni)

The magnetic structures of the two bismuth oxy-phosphate compoundsBiMPO5 (M2+ = Ni2+,Co2+) have been determined by neutron powder diffraction using group theory analysis as apreliminary tool. Both compounds adopt a monoclinic crystal structure (S.G.P 21/n,a = 7.1642(2) Å,b = 11.2038(3) Å,c = 5.1740(2) Åand β = 107.296(2)° for Ni2+ and a = 7.2441(1) Å, b = 11.2828(1) Å, c = 5.2258(1) Åand β = 107.841(1)° for Co2+). The refinement of the magnetic structures belowTN = 17.5 and 15 K,respectively, for both compounds show that the magnetic structure is characterized by the propagationvector k = (−1/2, 0, 1/2), with components given with respect to the reciprocal lattice of the nuclear structure. Thismeans a magnetic unit cell that is a multiple of the nuclear cell. The magnetic structure isconstituted of ferromagnetic pairs of metal ions antiferromagnetically coupled withindouble chains. The relative strength of the intra and inter double chains exchangeinteractions has been examined by establishing a theoretical magnetic phase diagram. Mostof the interactions come from M–O–O–M super–super-exchange paths. At its ground state,BiNiPO5 shows a nearly collinear arrangement of magnetic moments withm1.5 K = 2.13(3) μB/Ni. Due to the strongmagnetic anisotropy of Co2+ (m1.5 K = 3.52(3) μB/Co), the collinear character is largely lost while the magnetic structure remainsanalysable on the basis of the greatest isotropic component of the local moments.

Vanadium(III) phosphonate cage complexes

The synthesis and structural and magnetic characterisation of three new vanadium(III) phosphonate cage complexes are reported. The exchange interactions vary from −30 to +30 cm −1 and appear to be dependent on the superexchange path between vanadium centers.

Disorder in LixFePO4: From glasses to nanocrystallites

LixFePO4 glasses have been prepared by fast-quenching method in the whole range of composition 0⩽ x ⩽1. The amorphous state of glassy materials is confirmed by X-ray diffraction. Information concerning the local environment of Li and Fe cations and the configuration of (PO4)3− oxo-anions is obtained by Fourier transform infrared (FTIR) spectroscopy. While the LiFePO4 crystalline materials undergo a transition from the paramagnetic to the antiferromagnetic ordering at 52K, no magnetic ordering is observed in the vitreous samples that realize random field systems, so that a spin glass-like freezing is observed at low temperature. The paramagnetic Curie temperature of LixFePO4 is independent of x and shifted to θ=−60K in the glassy state, due to a significant distortion of the FeO6 octahedra that alters the superexchange path inside the atomic FeO4 layers of the crystallized structure. On another hand, the PO4 tetrahedra are not significantly distorted in the glassy phase. The results are compared with highly disordered, but nanocrystallized LiFePO4 recently obtained at the early stage of synthesis by solid state reaction at 300°C. In this latter case, the lack of long-range antiferromagnetic ordering is due to substitutional disorder among the cationic sublattice.

Impurity-induced singlet breaking inSrCu2(BO3)2

We have performed $\mu$SR studies on single crystals of SrCu$_2$(BO$_3$)$_2$, a quasi-two-dimensional spin system with a spin singlet ground state. We observe two different muon sites which we associate with muons located adjacent to the two inequivalent O sites. One site, presumed to be located in the Cu-O-Cu superexchange path, exhibits a large increase in the frequency shift with decreasing temperature which is unaffected by the singlet formation, indicating that the muon has locally broken the singlet bond. We have also performed $\mu$SR on single crystals of SrMg$_{0.05}$Cu$_{1.95}$(BO$_3$)$_2$, Sr$_{0.96}$La$_{0.04}$Cu$_2$(BO$_3$)$_2$, and Sr$_{0.95}$Na$_{0.05}$Cu$_2$(BO$_3$)$_2$. We have found that the frequency shifts of these doped samples are equivalent and contain three branches at low temperatures. Two of these branches map on to the branches observed in the pure sample reasonably well and so we attribute the third branch to effect of the dopants. Specifically, this third branch represents the case when the muon sits at a site in the superexchange path lacking a corresponding singlet, due to it already being broken as a result of doping. This then leads to the conclusion that singlets are broken in this system when it is doped both in and out of the CuBO$_3$ planes.

Magnetic ordering and electrical resistivity in Co 0.2Zn 0.8Fe 2O 4 spinel oxide

We report the magnetic, Mössbauer spectroscopy and resistivity measurements in order to understand the electronic behaviour of bulk Co 0.2Zn 0.8Fe 2O 4 spinel oxide. The effect of magnetic order on electrical behaviour is observed from the resistivity measurements in the absence and presence of magnetic field. The analysis of Mössbauer spectra suggests the absence of Fe 2+ ions in the system, which implies that complete hopping of charge carriers between localized Fe 3+/Co 2+ and Fe 2+/Co 3+ pair of ions in B sublattice is not the favourable mechanism in Co 0.2Zn 0.8Fe 2O 4. We suggest that electrical behaviour of the present sample may be consistent with a model of fractional charge transfer via Fe B 3+-O 2−-Co B 2+ superexchange path.

Magnetic instability and oxygen deficiency in Na-dopedTbMnO3

Oxygen vacancies in ${\mathrm{TbMnO}}_{3}$ were created by monovalent ${\mathrm{Na}}^{+}$ doping. The effects of the interruption of the superexchange paths on the spin orderings were investigated. Chemical doping resulted in a much higher ordering temperature, which is probably associated with enhanced $\mathrm{Tb}\text{\ensuremath{-}}\mathrm{Tb}$ coupling because of a reduction in $\mathrm{Tb}\text{\ensuremath{-}}\mathrm{Tb}$ interatomic distances. The oxygen vacancies turned the modulated Mn spin structure into a simple commensurate one, presumably due to interruptions of the in-plane $(\mathrm{Mn}\text{\ensuremath{-}}\mathrm{O})--(\mathrm{O}\text{\ensuremath{-}}\mathrm{Mn})$ superexchange paths, which reduced the significance of the next nearest-neighbor interactions of the Mn ions. The modulated spin structure of the Mn moments was found to reappear in systems with high Na doping, indicating that the anisotropic magnetic couplings had reemerged.

Lys-D48 Is Required for Charge Stabilization, Rapid Flavin Reduction, and Internal Electron Transfer in the Catalytic Cycle of Dihydroorotate Dehydrogenase B of Lactococcus lactis

Dihydroorotate dehydrogenase B (DHODB) catalyzes the oxidation of dihydroorotate (DHO) to orotate and is found in the pyrimidine biosynthetic pathway. The Lactococcus lactis enzyme is a dimer of heterodimers containing FMN, FAD, and a 2Fe-2S center. Lys-D48 is found in the catalytic subunit and its side-chain adopts different positions, influenced by ligand binding. Based on crystal structures of DHODB in the presence and absence of orotate, we hypothesized that Lys-D48 has a role in facilitating electron transfer in DHODB, specifically in stabilizing negative charge in the reduced FMN isoalloxazine ring. We show that mutagenesis of Lys-D48 to an alanine, arginine, glutamine, or glutamate residue (mutants K38A, K48R, K48Q, and K48E) impairs catalytic turnover substantially (approximately 50-500-fold reduction in turnover number). Stopped-flow studies demonstrate that loss of catalytic activity is attributed to poor rates of FMN reduction by substrate. Mutation also impairs electron transfer from the 2Fe-2S center to FMN. Addition of methylamine leads to partial rescue of flavin reduction activity. Nicotinamide coenzyme oxidation and reduction at the distal FAD site is unaffected by the mutations. Formation of the spin-interacting state between the FMN semiquinone-reduced 2Fe-2S centers observed in wild-type enzyme is retained in the mutant proteins, consistent with there being little perturbation of the superexchange paths that contribute to the efficiency of electron transfer between these cofactors. Our data suggest a key charge-stabilizing role for Lys-D48 during reduction of FMN by dihydroorotate, or by electron transfer from the 2Fe-2S center, and establish a common mechanism of FMN reduction in the single FMN-containing A-type and the complex multicenter B-type DHOD enzymes.

Electronic structure and magnetism in sodium nickelate: Density-functional and model studies

The electronic structure and magnetism in $\mathrm{Na}\mathrm{Ni}{\mathrm{O}}_{2}$ are studied from density-functional calculations and by solving model Hamiltonians, suggested from the density-functional results, to understand the magnetic exchange. The density-functional calculations within the LSDA approximation yield a layered antiferromagnetic solution with ferro-orbital ordering of the $\mathrm{Ni}(d)$ orbitals arising from the Jahn-Teller distortion around the ${\mathrm{Ni}}^{3+}$ ion in agreement with the orbital ordering inferred from neutron diffraction. The weak ferromagnetic interaction within the layer $({J}_{F}\ensuremath{\approx}1\phantom{\rule{0.3em}{0ex}}\mathrm{meV})$ is caused by the 90\ifmmode^\circ\else\textdegree\fi{} Ni-O-Ni exchange following the Goodenough-Kanamori-Anderson rules, while the weaker antiferromagnetic interaction between the layers $({J}_{AF}\ensuremath{\approx}\ensuremath{-}0.1\phantom{\rule{0.3em}{0ex}}\mathrm{meV})$ is mediated via a long Ni-O-Na-O-Ni superexchange path. In order to shed light on the differences between $\mathrm{Na}\mathrm{Ni}{\mathrm{O}}_{2}$ and $\mathrm{Li}\mathrm{Ni}{\mathrm{O}}_{2}$, which show very different magnetic behaviors in spite of the similarity of their crystal structures, we examine the effect of the coupling of the alkali atom (Na) motion to the electronic degrees of freedom on the interlayer exchange ${J}_{AF}$. A model Hamiltonian is proposed and solved by exact diagonalization and by using the variational Lang-Firsov method. We find that reducing the mass by going from Na to Li does reduce the strength of the magnetic exchange, but only by a small amount, so that the difference in mass alone cannot describe the differences in magnetic behavior between the two compounds. It is suggested that other electronic effects such as differences in orbital ordering could be responsible for the difference in magnetism between $\mathrm{Na}\mathrm{Ni}{\mathrm{O}}_{2}$ and $\mathrm{Li}\mathrm{Ni}{\mathrm{O}}_{2}$.

Ferrodistorsive orbital ordering in the layered nickelate NaNiO2: A density-functional study

The electronic structure and magnetism in the sodium nickelate NaNiO2 in the low-temperature phase is studied from density-functional calculations using the linear muffin-tin orbitals method. An antiferromagnetic solution with a magnetic moment of 0.7μB per Ni ion is found. A ferrodistorsive orbital ordering is shown to occur due to the Jahn–Teller distortion around the Ni+3 ion in agreement with the orbital ordering inferred from neutron diffraction. While the intralayer exchange is ferromagnetic, the interlayer exchange is weakly antiferromagnetic, mediated by a long Ni–O–Na–O–Ni superexchange path.

Hydrostatic pressure effects on the magnetic susceptibility of ruthenium oxide Sr 3Ru 2O 7: evidence for pressure-enhanced antiferromagnetic instability

Hydrostatic pressure effects on the temperature- and magnetic field dependencies of the in-plane and out-of-plane magnetization of the bi-layered perovskite Sr 3Ru 2O 7 have been studied by SQUID magnetometer measurements under a hydrostatic helium-gas pressure. The anomalously enhanced low-temperature value of the paramagnetic susceptibility has been found to systematically decrease with increasing pressure. The effect is accompanied by an increase of the temperature T max of a pronounced peak of susceptibility. Thus, magnetization measurements under hydrostatic pressure reveal that the lattice contraction in the structure of Sr 3Ru 2O 7 promotes antiferromagnetism and not ferromagnetism. The effects can be explained by the enhancement of the inter-bi-layer antiferromagnetic spin coupling, driven by the shortening of the superexchange path, and suppression, due to the band-broadening effect, of competing itinerant ferromagnetic correlations.

Electronic structure ofPbFe1/2Ta1/2O3:Crystallographic ordering and magnetic properties

We report electronic structure calculations for the multiferroic ferromagnetoelectric perovskite ${\mathrm{PbFe}}_{1/2}{\mathrm{Ta}}_{1/2}{\mathrm{O}}_{3},$ within density functional theory in the local spin density approximation (LSDA) and within the LSD+U approach. Our results, corresponding to several possible crystallographic and magnetic orderings, show the link between short range cation coordination and magnetic properties. In particular, the existence of two different N\'eel ordering temperatures, experimentally evidenced, is explained in terms of different superexchange paths introduced by crystallographic orderings certainly present, locally, in the real samples. The introduction of ferroelectric displacements, which are found to be in good agreement with experiment, do not bring about large changes in the electronic structure of this system.

Magneto-Structural Correlation in Di-μ-oxo Bridged Dicopper Complexes—Predictability of Isotropic Exchange-Coupling Constant from Structure

The relation between isotropic exchange-coupling constant and their structural parameters was examined using 117 compounds containing di-μ-oxo dicopper (CuO2Cu) moiety. The Cu–O bond distances should be in the range of covalent bonding region, preferably 1.93 Å and should be less than 2.25 Å for the superexchange path. The scatter plot between the Cu–O–Cu angle (φ) versus Cu ... Cu distance (r) suggests that large number of molecules have a Cu–O bond length of 1.93 Å, and their Cu ... Cu distances are determined by φ. The atoms attached to bridging oxygen and ligands of copper can influence the exchange-coupling constant to a larger extent when compared to other distortions like deviation from planarity and ideal bond lengths and angles. It is suggested that the superexchange pathway is ineffective at Cu–O distances greater than 2.25 Å resulting into |2J| < 50 cm–1 and no magneto-structural correlation for these systems could be given. The magneto-structural correlations are given by 2J [cm–1] = –99.1 φ [°] + 9587 = –4600 r [Å] + 13 226. A study including only four-coordinate copper atoms indicate that 2J = (2/rCu-O)(–74.8 φ + 7126 + B) where rCu-O is the Cu–O bond length and B is a correction term applied based on distortions and atoms attached to bridging oxygen and copper atoms. The above least-squares fit lines indicate continuity between antiferromagnetic and ferromagnetic regions crossing the 2J = 0 value at around 97°.

Atomic and magnetic structures, disorder effects, and unconventional superexchange interactions inA2MnGaO5+δ(A=Sr,Ca)oxides of layered brownmillerite-type structure

Crystal and magnetic structures of complex manganese oxides Sr2GaMnO5+delta (deltasimilar or equal to0.01,0.52) and Ca2GaMnO5+delta (deltasimilar or equal to0.05) were studied by neutron powder diffraction (ND) and muSR technique in the temperature range 2-300 K. The crystal structures contain single MnO2 layers separated by three nonmagnetic cation-oxygen layers. The principal difference between the deltasimilar or equal to0 and deltasimilar or equal to0.5 compounds is the Mn valence: Mn3+ or Mn4+, and the structure of the (GaO1+delta) buffer layer, which is formed by tetrahedra or partially filled octahedra, respectively. The magnetic moments of the manganese ions are coupled antiferromagnetically in the MnO2 plane, but antiferromagnetically (G type) or ferromagnetically (C type) between the planes for the reduced and oxidized compositions, respectively. The transition from the G- to C-type magnetic structure by oxygen doping is explained by strong diagonal 180degrees superexchange antiferromagnetic interaction between Mn4+-ions in the adjacent layers through additional oxygen atoms in the GaO buffer layer. The magnetic moments in Sr-based samples are appreciably reduced in comparison with the spin-only values of the corresponding Mn ion. By using complementary information on local magnetic field distribution from muSR we show that the reduced magnetic moments seen by ND are caused by the presence of locally flipped Mn spins and a short-ranged (40 Angstrom) antiferromagnetic phase. The magnetic disorder can be caused by the disorder observed in the oxygen positions of the GaO1+delta layer, because the coupling between the MnO2 layers is mediated by the geometry of the superexchange path through these oxygen atoms.

Effect of metal-ligand bond lengths on superexchange interactions in Jahn-Teller d(4) ion systems: spin dimer analysis of the magnetic structure of marokite CaMn(2)O(4).

In marokite CaMn(2)O(4), all six Mn-O bonds of each MnO(6) octahedron are different because of the Jahn-Teller distortion so that every Mn(3+) (d(4)) ion has six different superexchange interactions with its neighboring Mn(3+) ions. The spin exchange interactions of CaMn(2)O(4) were examined on the basis of spin dimer analysis to find what geometrical parameters of the Mn-O-Mn superexchange paths control the signs and strengths of their spin exchange interactions. Our work correctly describes the magnetic structure of CaMn(2)O(4) observed from neutron powder diffraction measurements and shows that the antiferromagnetic interactions of the Mn-O-Mn paths depend primarily on the asymmetry and the Mn-O bond length of the Mn-O-Mn bridge, but not on the 90 degree angle Mn-O-Mn bond angle.

Effect of Pr–O hybridization on the anomalous magnetic properties of Pr1+xBa2−xCu3O7−y system

The Pr L3-edge x-ray absorption near edge structure spectra and antiferromagnetic TN(Pr) data for the parent system PrBa2Cu3O7−y (0⩽y<1) and the oxygenated system Pr1+xBa2−xCu3O7−y (0⩽x⩽1; −0.27⩽y⩽0.05) are reported. The formal Pr valence in the PrO8 cage decreases from 3.18 for PrBa2Cu3O6.95 [TN(Pr)=18.5 K], to 3.12 for Pr1.2Ba1.8Cu3O6.98 (15.5 K), 3.03 for Pr1.6Ba1.4Cu3O7.16 (8 K), and 3.00 for Pr2BaCu3O7.27 [TN(Pr) not observed]. The Pr valence depends both on the number of holes available in the PrO8 cage and the Pr 4f-O 2pπ hybridization strength. On the other hand, anomalous TN(Pr) is a direct result of exchange interaction though Pr–O–Pr hybridization. However, the relative contribution from PrIV–PrIV superexchange via strong Pr–O orbital hybridization and PrIII–PrIII/PrIII–PrIV superexchange paths is unclear.

Synthesis, characterization and X-ray structures of the new dinucleating ligand 2,8-dimethyl-1,4,5,6,7,10,11,12-octahydroimidazo[4,5-h] imidazo[4,5-c][1,6]diazecine-5,11-diethanoic acid and its Cu(II) complex; an alternating chain of Cu(II) ions, coupled both intramolecularly and intermolecularly

The design and synthesis of a new, rigid dinucleating ligand 2,8-dimethyl-1,4,5,6,7,10,11,12-octahydroimidazo[4,5-h] imidazo[4,5-c][1,6]diazecine-5,11-diethanoic acid (H2glymeim) is reported together with its molecular and crystal structure. The rigid ligand structure is confirmed by the structure and magnetic properties of its bis Cu(II) complex, [Cu2(C16H22N6O6)(H2O)4](ClO4)2(H2O)2, (Cu2glymeim). Crystals of free glymeim are composed of units of C16H22N6O4 and eight water molecules linked by a two dimensional network of hydrogen bonds. Six of them contribute to a one-dimensional network that links the organic molecules. The 1,6-diazecine ring shows a chair conformation, with expected angles and bond distance values. A stretched conformation of the glycine residue is observed in the free ligand. When this residue is coordinated, it produces significant stress over the diazecine ring caused by the closure of the glycine residue around the metal ion. The copper complex has a dinuclear structure with a square pyramidal environment around both metal ions. The apical position in the two pyramids point to opposite directions in the molecule and they are related by an inversion center. The pyramidal bases of both copper atoms are in the same plane. The intramolecular metal–metal distance in the complex is 7.445(3) Å. However, the shortest distance is of intermolecular nature, with a value of 5.378(2) Å. The crystal structure of the complex consists of a chain of dinuclear units, with an alternating chain arrangement. Low temperature magnetic susceptibility and EPR are in agreement with an antiferromagnetic dinuclear behavior in solution and like a linear chain uniformly spaced, with J=−8.54 cm−1 and α=1. The magnetic behavior of this compound can be explained as the result of an intramolecular magnetic exchange (long distance), and a superexchange path through the hydrogen bond network between adjacent dinuclear molecules.