Variable-temperature Magnetic Measurements Research Articles

Well isolated copper(II) pyrazine-bridged chains: synthesis and magneto-structural analysis of 2-halo-4-pyridone perchlorate complexes

Two new coordination polymers, [Cu(pz)(L)2(H2O)2](ClO4)2 (L = 2-Cl- (1) or 2-Br-4-pyridone (2); pz = pyrazine), have been synthesized and characterized by X-ray diffraction, EPR and variable temperature magnetic measurements. Both compounds crystallize as well isolated pyrazine-bridged chains with the heterocyclic ligands in the pyridone tautomer and coordinated via the oxygen atom. The Cu ions possess Jahn-Teller elongated octahedral geometries with the Jahn-Teller axis along the Cu-O axis. The water molecules in 2 are inequivalent with one molecule semi-coordinate (dCu… O = 3.225(6) Å) at an occupancy of 0.72. Both compounds exhibited axial powder EPR spectra, as expected. Variable temperature magnetic measurements are well fit by the uniform chain Heisenberg antiferromagnetic model with J = −10.74(4) K (1) or = −10.64(2) K (2). Comparison with the known 3-halo-4-pyridone compounds suggests an inverse relationship between the Cu-pz-Cu distance and the strength of the magnetic exchange.

Heptanuclear Mixed-Valence Co4IIICo3II Molecular Wheel─A Molecular Analogue of Layered Double Hydroxides with Single-Molecule Magnet Behavior and Electrocatalytic Activity for Hydrogen Evolution Reactions.

We present a bifunctional heptanuclear cobalt(II)/cobalt(III) molecular complex formulated as [Co7(μ3-OH)4(H2L1)2(HL2)2](NO3)6·6H2O (1) (where H5L1 is 2,2'-(((1E,1'E)-((2-hydroxy-5-methyl-1,3-phenylene)bis(methanylylidene))bis(azanylylidene))bis(propane-1,3-diol)) and H2L2 is 2-amino-1,3-propanediol). Compound 1 has been characterized by single-crystal X-ray diffraction analysis along with other spectral and magnetic measurements. Structural analysis indicates that 1 contains a mixed-valence Co7 cluster where a central Co(II) ion is connected to six different Co centers (four CoIII and two CoII ions) by four μ3-OH groups, giving rise to a planar heptanuclear cluster that resembles a molecular fragment of a layered double hydroxide (LDH). Two triply deprotonated (H2L1)3- ligands form the outer side of the cluster while two singly deprotonated (HL2)- ligands are located at the top and bottom of the central heptanuclear core. Variable temperature magnetic measurements indicate the presence of weak ferromagnetic CoII···CoII interactions (J = 3.53(6) cm-1) within the linear trinuclear CoII cluster. AC susceptibility measurements show that 1 is a field-induced single-molecule magnet (SMM) with τ0 = 8.2(7) × 10-7 s and Ueff = 11.3(4) K. The electrocatalytic hydrogen evolution reaction (HER) activity of 1 in homogeneous phase shows an overpotential of 455 mV, with a Faradaic efficiency of 81% and a TOF of 8.97 × 104 μmol H2 h-1 mol-1.

Cobalt and nickel homobinuclear metallomacrocycles based on the redox-active bis-semiquinonato ligands as potential functional absorbing materials

Recently obtained bis-o-quinone with resorcinol as a bridge was utilized for synthesis of cobalt and nickel homobinuclear complexes. Two bis-o-semiquinonato metal fragments are situated co-facially to each other forming metallomacrocycle. Metals in both fragments bond diethyl ether solvate molecules externally as well as internally in the cell. At 100 K one of two metal atoms in the macrocycle is five-coordinated whereas the other one is six-coordinated due to internal solvent molecule. Heating to room temperature results in disordering of internal solvent molecule in two positions: coordinated to different nickel atoms. Variable temperature magnetic measurements indicate both complexes to be bis-o-semiquinonato anion-radical adducts of high spin metals with magnetic interactions inside of bis-o-semiquinonato units. Sign and energy of interactions depend on the coordination number of metal. Exchange interactions between units are weak. UV–Vis absorption spectrum is determined by ligands centered bands. CV indicates reversible reduction processes involving redox active dioxolene ligands.

Trinuclear manganese and zinc clusters and a dinuclear manganese complex with multiple oxo-bridges: Syntheses, structures, and magnetic properties of the MnII compounds and luminescent property of the ZnII complex

Two trinuclear clusters [Mn3(L1)2] (1) and [Zn3(L1)2] (2) have been prepared from the reactions of Mn(CH3COO)2·4H2O and Zn(CH3COO)2·4H2O, respectively, with a hydroxy-rich Schiff-base ligand H3L1 (H3L1 = 2-{[bis(2-hydroxy-3-methoxybenzyl)(amino-ethyl)amino]methyl}phenol). One dinuclear compound [Mn2(HL2)Cl2] (3) was synthesized from the treatment of MnCl2·4H2O with another hydroxy-rich Schiff base ligand H3L2 (H3L2 = 2-{[bis(2-hydroxy-3-methoxybenzyl)(amino-ethyl)amino]ethyl}phenol). Complexes 1–3 were characterized by single-crystal X-ray diffraction analysis. The structural analyses indicated that complexes 1 and 2 are isostructural and contain linear MnII–MnII–MnII and ZnII–ZnII–ZnII cores. In compounds 1–3, the metal centers are doubly bridged by phenoxido groups of the ligands. Variable temperature magnetic measurements of 1 and 3 revealed the presence of antiferromagnetic intramolecular couplings, and the magnetic susceptibility data are consistent with S = 5/2 of the MnII ions. The luminescent property of compound 2 was investigated. The 3d10 zinc compound 2 exhibited strong luminescence with λmax = 491 nm (for λex = 418 nm).

A copper(II) chloride coordination compound with an adamantane-like core

A new tetracopper(II) coordination compound, [Cu4Cl6O(iQuin)4] (1, iQuin = isoquinoline), with an adamantane-like structure is reported. The compound crystallizes in the tetragonal space group P4/n with one crystallographically unique Cu(II) and oxide ions, and two chloride ions. Variable temperature magnetic measurements reveal dominant antiferromagnetic interactions, but the crystal structure suggests the likelihood of magnetic frustration in the compound. Modeling results indicate the presence of two competing interactions, and (ap = apical; eq = equatorial), as well as a Zeeman coupling of the Cu(II) ions with the external magnetic field. All data were fit using the Hamiltonian

Synthesis of copper(II) halide dimers with 2-amino-5-methylpyridine and serendipitous copper catalyzed synthesis of 3-bromo-2-ethyl-5-methyl-1H-pyrrolo[2,3-b]pyridine

Reaction of CuX2·nH2O (X = Cl, n = 2; X = Br, n = 0) with 2-amino-5-methylpyridine (5MAP) in acetonitrile yielded [(5MAP)2CuX2]2 (1, Cl; 2, Br). The compounds are isomorphous and crystallize in the monoclinic space group P21 /n as bihalide bridged dimers. Variable temperature magnetic measurements show very weak exchange in the two compounds (-2.1(1) K) which may correlate with previously proposed magnetostructural correlations for bihalide bridged Cu(II) dimers. In attempts to prepare 2 in 2-butanone as solvent, [(3-Br-2-Et-5-Mepyrpy)(CH3CO2)4Cu2] (3) was serendipitously isolated (3-Br-2-Et-5-Mepyrpy = 3-bromo-2-ethyl-5-methyl-7H-pyrrolido[2,3-b]pyridinium). The bicyclic ligand was synthesized in situ by condensation of 5MAP with the solvent; the acetate ions were generated by copper(II) catalyzed Baeyer-Villiger oxidation of the solvent. A mechanism for the synthesis is proposed. The resulting Cu-paddlewheel compound exhibits strong (-400 K) antiferromagnetic interactions.

A family of methoxide-bridged Cu(II) compounds with N-heterocyclic ligands: dimers and chains

Three new methoxide-bridged Cu(II) dimers are reported: tetrakis(2-methylpyrazine)di(μ-methoxy)diperchloratodicopper(II) (1), tetrakis(2-amino-5-iodopyridine)dibromide-di-μ-methoxydicopper(II) tetramethanol (2) and catena[(2-amino-5-methylpyridine)μ-bromido-μ-methoxycopper(II) (3). The compounds were characterized by single-crystal X-ray diffraction and variable temperature magnetic measurements. All three compounds crystallize in the triclinic space group P-1, and the dimers lie across a crystallographic inversion center. The dimers in 3 are further bridged into an alternating chain motif via semi-coordinated Cu(II)/Br interactions. All three compounds exhibit strong antiferromagnetic interactions with J/kB = −348(8) K for 1, and the exchange in 2 and 3 being too strong to estimate from the available data. The magnetic data for 1-3 are dominated by trace paramagnetic impurities at temperatures below 200 K. Correlation of the structures with the observed magnetic behavior is proposed.

Coordination chemistry and magnetic properties of copper(II) halide complexes of quinoline

Complexes Cu(quin)2X2 [quin = quinoline, X = Cl (1), Br (2)] have been prepared and characterized via single-crystal X-ray diffraction and variable temperature magnetization measurements. The compounds are isomorphous in the monoclinic space group C2/c and crystallize as square planar complexes linked into chains via short X…X contacts. Magnetic susceptibility data were collected over the temperature range 1.8–300 K and were fitted to the one-dimensional Heisenberg antiferromagnetic model yielding J/kB = −33.7(5) K (1) and −145(4) K (2) with the larger exchange in the bromide complex a result of greater overlap due to the larger van der Waals contribution. Low temperature data indicate the presence of some short chains in the sample which provide for a paramagnetic contribution (odd length chains) or diamagnetic contribution (even length chains) at the lowest temperatures.

Transition metal halide complexes of 4′-aminoacetophenone: Syntheses, structures, and magnetic behavior

A family of eight compounds of the general formula [(C8H9NO)2MX2] or [(C8H9NO)2(H2O)2MX2], (M = Ni, Co, Cu, Zn; X = Cl, Br) has been prepared and the compounds characterized by combustion analysis, IR, single-crystal X-ray diffraction and variable temperature magnetization measurements. [[(C8H9NO)2(H2O)nMX2], (1, n = 0, M = Cu, X = Cl; 2, n = 0, M = Cu, X = Br; 3, n = 2, M = Ni, X = Cl; 4, n = 2, M = Ni, X = Br; 5, n = 2, M = Co, X = Cl; 6, n = 2, M = Co, X = Br; 7, n = 0, M = Zn, X = Cl; 8, n = 0, M = Zn, X = Br.) The eight compounds crystallize in three distinct space groups and have coordination number of either four (compounds 1, 2, 7, and 8) or six (compounds 3–6). Compounds 1 and 2 are slightly distorted square planar, compounds 3–6 are slightly distorted octahedral, and compounds 7 and 8 are slightly distorted tetrahedral. All eight compounds form chains either through bihalide interactions (1 and 2) or systems of hydrogen bonds (3–8). Chains are linked into layers through short halide…halide (1, 2, 7) and both traditional and non-traditional hydrogen bonds. The complexes have also been studied via variable temperature magnetic susceptibility measurements. Data for Cu(II) complexes 1 and 2 the 1D-Heisenberg uniform chain model with J/kB of −13.4(6) K and −14.3(4) K, respectively, with antiferromagnetic interchain interactions (θ = −4.1(5) K, −2.5(5) K, respectively) following the H=-J∑si∙sj Hamiltonian. The Ni(II) and Co(II) compounds showed temperature dependent moments which were well-modeled as arising due to single-ion anisotropy.

Exploration of Variable Temperature Magnetism and Electrical Properties of a Pyridyl-isonicotinoyl Hydrazone Bridged Three-Dimensional Mn-Metal–Organic Framework with a Thiophene Dicarboxylato Link

In emerging trends in our technology-dependent society, the applicability of multifunctional coordination polymers (CPs) and metal–organic frameworks is highly stimulating. In search of such chemical compounds, a Mn(II), d5, based metal–organic framework (MOF), {[Mn2(tdc)2(pcih)2(EtOH)]n} (1), has been designed with the coordination of multidentate ligands tdc2– (2,5-thiophene dicarboxylato) and pcih (pyridine-4-carboxaldehyde isonicotinoylhydrazone). The structure determination by single crystal X-ray diffraction has revealed the formation of three-dimensional (3D) supramolecular architecture via the combined nearly perpendicular bridging of pcih and tdc2– ligands. A variable temperature magnetic measurement of 1 shows weak antiferromagnetism (χMT, 9.41 cm3 K mol–1 at 300 K) with two as good as “isolated” Mn(II) centers (S = 5/2 with g ≈ 2.07). Magnetic exchange is considered through 9/10 carboxylato bridged atoms inclusively spanning two Mn(II) centers at a distance of 4.114 Å. Interestingly, the 3D assembly of 1 exhibits electrical conductivity in the semiconducting region (band gap, 3.72 eV; barrier height, 0.65 eV; series resistance, 0.03 Ω). A Schottky barrier diode feature is recorded at a threshold potential of 0.19 V and follows a non-ohmic relation (I α V2), and the conductivity is 3.42 × 10–5 S m–1. A galvanostatic charge–discharge (GCD) experiment measures the moderate specific capacitance of 1 F/g at a 2 mV/s scan rate.

A Series of Rare-Earth Mesoionic Carbene Complexes.

We report the synthesis and characterisation of a series of rare-earth mesoionic carbene complexes, [RE{N(SiMe3 )2 }3 {CN(Me)C(Me)N(Me)CH}] (3RE, RE=Sc, Ce, Pr, Sm, Gd, Tb, Dy, Ho, Er, Tm, Yb, and Lu), greatly expanding the limited library of f-block mesoionic carbene complexes. These complexes were prepared by treatment of the parent RE-triamides with an N-heterocyclic olefin (NHO), where an NHO backbone proton undergoes a formal 1,4-proton migration to the NHO-methylene group. For all RE(III) metals, as expected, quantum chemical calculations suggest only a σ-component to the metal-carbene bonding, in contrast to a previously reported uranium(III) congener where the 5f3 metal engages in a weak π-back-bond to the MIC. All complexes were characterised by static variable-temperature magnetic measurements, and dynamic magnetic measurements reveal that 3Dy and 3Er are field-induced single-molecule magnets (SMMs), with Ueff energy barriers of 35 and 128 K, respectively. Complex 3Dy is, as expected, a poorly performing SMM, but conversely 3Er performs unexpectedly well.

Morphological Studies of Composite Spin Crossover@SiO2 Nanoparticles.

Spin crossover (SCO) iron (II) 1,2,4-triazole-based coordination compounds in the form of composite SCO@SiO2 nanoparticles were prepared using a reverse microemulsion technique. The thickness of the silica shell and the morphology of the as obtained core@shell nanoparticles were studied by modifying the polar phase/surfactant ratio (ω), as well as the quantity and the insertion phase (organic, aqueous and micellar phases) of the tetraethylorthosilicate (TEOS) precursor, the quantity of ammonia and the reaction temperature. The morphology of the nanoparticles was monitored by transmission electron microscopy (TEM/HRTEM) while their composition probed by combined elemental analyses, thermogravimetry and EDX analyses. We report that not only the particle size can be controlled but also the size of the silica shell, allowing for interesting perspectives in post-synthetic modification of the shell. The evolution of the spin crossover properties associated with the change in morphology was investigated by variable temperature optical and magnetic measurements.

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Complex Featuring Two Double Dative Bonds Between Carbon(0) and Uranium

Non-covalent interactions governing the supramolecular assembly of copper(II) complexes with hydrazone-type ligand: Experimental and quantum chemical study

A series of two new mono- and one binuclear µ-nitrato bridged copper(II) complexes [Cu(L)(HL)]ClO4 (1), [Cu(HL)(NO3)(H2O)]2NO3∙H2O (2) and [Cu2(L2)(µ-NO3)2] (3), with an unsymmetrical NNO donor Schiff base (HL) have been synthesized and characterized by elemental analysis, FTIR, CV, UV–vis and EPR spectroscopy. Their molecular structures were also determined by single crystal X-ray crystallography. In the binuclear complex 3, the Cu⋯ Cu distance is 3.494 Å. In 1, 2 and 3, the Cu(II) centers have distorted square pyramidal geometry (τ5 = 0.05–0.17). Evidence of weak π⋯π stacking intermolecular interactions along with other non-covalent interactions (hydrogen bonding) was observed by analyzing the respective crystal structures of the complexes. Thus, these hydrogen bonds, π⋯π stacking interactions and other weak intermolecular interactions establish in the form of supramolecular architectures a crystalline “network” environment. The non-covalent interactions were also investigated by employing Hirshfeld Analysis. The room temperature magnetic moments of the mononuclear complexes are less than the spin only values which are indicative of small interactions. Also, significant magnetic interactions were not exhibited by binuclear copper(II) complex 3 in the variable temperature magnetic measurements. The X-band EPR spectra of all three complexes exhibit copper(II) hyperfine structures as well as zero-field splitting which are appropriate for the triplet states of dimers. In complexes 1 and 2, the presence of pseudo dipolar interactions is proposed. Quantum chemical calculations (DFT) were carried out on complexes 1–3 to explore the electronic and spectral properties of these newly synthesized complexes. These complexes show significant antiproliferative and SOD activity. The SOD activity measured in terms of kMcCF is in the range 4.94–12.31 (mol L)−1s−1)× 104.

Hydrothermal synthesis, structure and variable temperature magnetic performance of polyferric sulfate with µ 3-O2- and µ 3-OH--centered Trinuclear Ferric(III)

A novel inorganic coordination polymers crystal is grown from ferric sulfate solution under hydrothermal condition in the presence of adipic acid. The single crystal structure analysis shows that 0.5[Fe6(μ3-O2-)2(μ3-OH-)2(SO4)6].2H2O 1 is composed of µ 3-O2- and µ 3-OH--centered Trinuclear Ferric(III) secondary building units (SUBs) to form two dimensional network, and the lattice parameters are a = 18.223(13) Å, b = 7.670(5) Å, 9.932(7) Å, α = β= γ = 90°, orthorhombic crystal system, Cmc21 space group, V = 1388.3(17) Å3. Squid-VSM magnetic measurement system is used for characterizing the variable temperature magnetic properties measurement of reaction products, and the result indicates that the magnetic susceptibility is obvious reduced with the increasing of test temperature. Noticeably, the higher magnetic susceptibility is acquired at about 0 K. Consequently, the products can be used as a good candidate for magnetic memory materials.

A Three‐Dimensional Pentanuclear Co(II) Coordination Polymer: Structural Topology, Hirshfeld Surface Analysis and Magnetic Properties

AbstractA 3D pentanuclear coordination polymer of Co(II); {[Co5(L2‐)4(HL‐)2(bpmp)2 (H2O)2].(H2O)5}n (CP1) was synthesized by the self‐assembly of semi‐flexible 5‐benzylamino‐isophthalic acid (H2L) and N‐donor auxiliary ligand 1,4‐bis(4‐pyridinylmethyl)piperazine (bpmp) using Co(NO3)2 ⋅ 6H2O under hydrothermal condition. The CP1 has been structurally characterized by elemental analysis, TGA, Powder‐XRD and IR spectroscopy which was further corroborated by single crystal X‐ray studies. Structurally, it is a 3D pentanuclear cobalt cluster secondary building units (SBUs) which are formed by carboxylates oxygen of H2L and nitrogen of bpmp. The topological analysis revealed that CP1 possesses a 2‐nodal 5,6‐connected three‐dimensional (3D) coordination framework with pcu net. Variable temperature magnetic measurements demonstrate that CP1 shows antiferromagnetic behavior.

(M,Ru)O2 (M = Mg, Zn, Cu, Ni, Co) Rutiles and Their Use as Oxygen Evolution Electrocatalysts in Membrane Electrode Assemblies under Acidic Conditions

The rutiles (M,Ru)O2 (M = Mg, Zn, Co, Ni, Cu) are formed directly under hydrothermal conditions at 240 °C from potassium perruthenate and either peroxides of zinc or magnesium, or poorly crystalline oxides of cobalt, nickel or copper. The polycrystalline powders consist of lath-shaped crystallites, tens of nanometres in maximum dimension. Powder neutron diffraction shows that the materials have expanded a axis and contracted c axis compared to the parent RuO2, but there is no evidence of lowering of symmetry to other AO2-type structures, supported by Raman spectroscopy. Rietveld refinement shows no evidence for oxide non-stoichiometry and provides a formula (MxRu1-x)O2 with 0.14 < x < 0.2, depending on the substituent metal. This is supported by energy-dispersive X-ray analysis on the transmission electron microscope, while Ru K-edge XANES spectroscopy shows that upon inclusion of the substituent the average Ru oxidation state is increased to balance charge. Variable temperature magnetic measurements provide evidence for atomic homogeneity of the mixed metal materials, with suppression of the high temperature antiferromagnetism of RuO2 and increased magnetic moment. The new rutiles all show enhanced electrocatalysis compared to reference RuO2 materials for oxygen evolution in 1 M H2SO4 electrolyte at 60 °C, with higher specific and mass activity (per Ru) than a low surface area crystalline RuO2, and with less Ru dissolution over 1000 cycles compared to an RuO2 with a similar surface area. Magnesium substitution provides the optimum balance between stability and activity, despite leaching of the Mg2+ into solution, and this was proved in membrane electrode assemblies.

Cobalt halide complexes of 2-, 3- and 4-methoxyaniline: Syntheses, structures and magnetic behavior

A family of six cobalt(II) compounds of the general formula (nMeO-C6H4NH2)2CoX2, (X = Cl, Br; nMeO-C6H4NH2 = 2-MeO-, 3-MeO-, or 4-MeO-aniline) has been prepared and the compounds characterized by combustion analysis, IR, single-crystal X-ray diffraction and variable temperature magnetization measurements [(n-MeOC6H4NH2)2CoX2, (1, n = 2, X = Cl; 2, n = 2, X = Br; 3, n = 3, X = Cl; 4, n = 3, X = Br; 5, n = 4, X = Cl; 6, n = 4, X = Br]. Although the six compounds crystallize in a variety of space groups, they are all isocoordinate. The compounds are slightly distorted tetrahedra. In all compounds, hydrogen bonds and short intermolecular X…Co contacts link the molecules into chains. For 3–6, short halide…halide contacts, in some cases short enough to be considered halogen bonds, further link the chains into layer structures. The complexes have also been studied via variable temperature magnetic susceptibility measurements. All six compounds exhibit antiferromagnetic exchange and show maxima in χ in the range 2–5 K. They have been fit to a variety of models incorporating single-ion anisotropy (SIA), and/or Heisenberg or Ising 1D- and 2D-systems. The results indicate that both antiferromagnetic superexchange and SIA are likely present in all compounds to some degree, but their relative contributions vary greatly. The potential superexchange pathways are discussed in terms of the observed magnetic properties and structures.

Ga2.52V2·48O7·33(OH)0.67, a synthetic member of the nolanite/akdalaite-type family of oxyhydroxides containing trivalent vanadium

The oxyhydroxide Ga2.52V2·48O7·33(OH)0.67 is prepared by reaction between Ga metal and Na3VO4 in a 1:1 monoethanolamine:water mixture at 240 ​°C. Powder neutron diffraction shows the material to be isostructural with the minerals nolanite and akdalaite, with cations occupying tetrahedral and octahedral interstitial sites in a hexagonal close-packed array of oxide/hydroxide (P63mc, a ​= ​5.7906(2) Å, c ​= ​9.2550(5) Å). Rietveld refinement against the data shows that Ga preferentially occupies tetrahedral sites, as well as some octahedral sites, and hence all V is octahedrally coordinated. The oxidation state of vanadium is confirmed as close to V3+ using V K-edge X-ray absorption near-edge structure spectroscopy, consistent with the refined chemical composition. The material is metastable, dehydrating around 300 ​°C and then decomposing above 500 ​°C, as shown by thermogravimetric analysis and thermodiffraction. The oxide Ga2.52V2.48O8 produced after dehydration at 300 ​°C is shown to contain a larger proportion of V4+ than the parent oxyhydroxide, to ensure charge balance, but the essential hexagonal structure is maintained. Variable temperature magnetisation measurements show that although both materials appear to obey the Curie-Weiss law at high temperatures, at low temperatures the inverse susceptibility curves are non-linear. There is, however, no evidence for strong magnetic exchange and the extracted effective moments are consistent with the presence of more V3+ in the oxyhydroxide compared to the oxide.

Metal-directed supramolecular architectures based on the bifunctional ligand 2,5-bis(1H-1,2,4-triazol-1-yl)terephthalic acid.

By the solvothermal reactions of 2,5-bis(1H-1,2,4-triazol-1-yl)terephthalic acid (H2L) with transition-metal ions, two novel polymeric complexes, namely, poly[diaqua[μ4-2,5-bis(1H-1,2,4-triazol-1-yl)terephthalato]cobalt(II)], [Co(C12H6N6O4)(H2O)2]n, (1), and poly[[diaqua[μ4-2,5-bis(1H-1,2,4-triazol-1-yl)terephthalato]nickel(II)] dihydrate], {[Ni(C12H6N6O4)(H2O)2]·2H2O}n, (2), were isolated. Both polymers have been characterized by FT-IR spectroscopy, elemental analysis and single-crystal X-ray diffraction analysis. The complexes have similar two-dimensional layered structures and coordination modes. Furthermore, the two-dimensional layered structures bear distinct intermolecular hydrogen-bonding interactions and π-π stacking interactions to form two different three-dimensional supramolecular networks based on 44-subnets. The structural variation depends on the nature of the metal cations. The results of variable-temperature magnetization measurements (χMT-T and χM-1-T) show that complexes (1) and (2) display antiferromagnetic behaviour.