Syntheses, structures and properties of two new neodymium complexes with N-P-acetamidobenzenesulfonyl-glycine acid

Two new neodymium complexes, [Nd₂(abglyH)₆(2,2′-bipy)₂(H₂O)₂] · 4H₂O 1 and {[Nd(abglyH)₃(H₂O)₂] · (4,4′-bipy) · 7H₂O}_n 2 (abglyH₂ = N-P-acetamidobenzenesulfonyl-glycine acid, 2,2′-bipy = 2,2′-bipyridine, 4,4′-bipy = 4,4′-bipyridine), have been synthesized and their structures have been measured by X-ray crystallography. In 1, nine-coordinated Nd(III) ions are bridged by two syn–syn bidentate and two tridentate bridging carboxylate groups from four different abglyH⁻ anions to form dinuclear motifs, which are further connected into a 3-D supramolecular framework via hydrogen bonds between the binuclear motifs and the uncoordinated water molecules. In 2, eight-coordinated Nd(III) ions are linked by six carboxylate groups adopting a syn–syn bidentate bridging fashion to form a 1-D inorganic–organic alternating linear chain. These polymeric chains generate microchannels extending along the a direction, and these cavities are occupied by discrete tetradecameric water clusters, which interact with their surroundings and finally furnish the 3-D supramolecular network via hydrogen bonds. At the same time, π–π stacking interactions between benzene rings from abglyH⁻ anions also play an important role in stabilizing the network.     

Three isostructural 3D supramolecules with <Emphasis Type="Italic">p</Emphasis>-thioacetatebenzoic acid ligand: syntheses,structure characterizations,and properties

Abstract  

p-Thioacetatebenzoic acid (H₂L) and a combination of N-donor ligand of 4,4′-bipyridine (4,4′-bipy) with metal(II) ions give rise to three 3D supramolecules of general formula [M(HL)₂(4,4′-bipy)₂(H₂O)₂] · H₂O, M = Co^II (1), Zn^II (2), Ni^II (3), which were characterized by crystallographic methods. The crystals are isostructural and belong to the triclinic P[`1] P\bar{1} space group. The structure can be considered to construct from 1D chains and further linked by hydrogen bonds into the final 3D supramolecular networks. The electrochemical behavior of complexes 1 and 3 were studied by cyclic voltammetry, indicating that the electron transfers in the electrode reaction are irreversible. Meanwhile, complex 2 exhibits significantly red-shifted emission in solid state at room temperature.     

Studies on the magnetic properties of two cobalt(II) complexes bearing 1,4-phenylenediacetate ligands

One reported compound [Co(PDA)(4,4′-bipy)]_n·nH₂O and one new compound [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O were prepared by the reactions of Co(NO₃)₂·6H₂O or Co(OH)₂ with 1,4-phenylenediacetic acid (H₂PDA) in the presence of the ancillary ligands 4,4′-bipyridine (4,4′-bipy) or imidazole (Im), and their magnetic properties were investigated. The presence of 4,4′-bipy in [Co(PDA)(4,4′-bipy)]_n·nH₂O results in a μ ₃-bridging mode of the PDA²⁻ ligand with one μ ₂-carboxylato group and one chelating carboxylato group and the construction of a 2D framework as reported in the literature. The introduction of Im ligand in [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O helps to construct a one dimensional chain with the two carboxylato groups of PDA²⁻ ligand in monodentate coordination modes. The magnetic studies reveal the presence of dominant antiferromagnetic interaction in [Co(PDA)(4,4′-bipy)]_n·nH₂O with a field-induced magnetic transition due to spin-flop. Magnetically, [Co(PDA)(Im)₂(H₂O)₂]_n·nH₂O presents a mononuclear structure. This work reveals that the introduction of ancillary ligands in the Co(II)-PDA system adjusts the linking modes of PDA²⁻ and therefore the resulting frameworks and their magnetic properties.     

Two New 2D and 1D Ni(II) Coordination Polymers Bridged by Vanadium-Substituted Keggin Polyoxotungstophosphates: Hydrothermal Synthesis and Crystal Structure

Two coordination polymers based on vanadium-substituted Keggin polyoxotungstophosphates as bridging ligands, {[Ni(4,4′-bipy)_1.5(OH)(H₂O)]₂[H₃PW₁₀V₂O₄₀]}·4H₂O (4,4′-bpy = 4,4′-bipyridine) 1 and {[Ni(dpa)₂][Ni(dpa)(H₂O)₃]₂[PW₉V₃O₄₀]}·4H₂O (dpa = 2,2′-dipyridylamine) 2, have been obtained by hydrothermal reactions and characterized by elemental analysis, IR, XRD, TGA and single-crystal X-ray Diffraction analysis. Compound 1 is a 2D layered structure built from 1D infinite zigzag {Ni₂(4,4′-bipy)₃(OH)₂(H₂O)₂}_n²⁺ chains bridged via [H₃PW₁₀V₂O₄₀]²⁻ anions. Compound 2 exhibits a one-dimensional chain-like structure constructed from [Ni(dpa)₂]²⁺ fragments bridged via bis-supported Keggin polyoxoanions [Ni(dpa)(H₂O)₃]₂[PW₉V₃O₄₀]²⁻. The two examples demonstrate that vanadium-substituted Keggin polyoxometalates have greater coordination capability.     

Coordination polymers with adamantanediacetate bridges: syntheses, structures, and magnetic properties

Abstract  Two new coordination polymers, [CoL(bpp)] _n (1) and [MnL(bipy)] _n ·0.25nH₂L·0.5nH₂O (2) (H₂L = 1,3-adamantanediacetic acid, bpp = 1,3-bis(4-pyridyl)propane, bipy = 4,4′-bipyridine), were synthesized and characterized by single crystal X-ray diffraction, IR spectroscopy, and thermal analysis. Complex 1 is an one-dimensional (1D) chain structure of Co(II) bridged by L²⁻ as well as bpp. Complex 2 consists of a two-dimensional (2D) (3,6)-connected topology layer structure. Variable temperature magnetic susceptibility measurements in the range of 2–300 K reveal the existence of weak antiferromagnetic interactions in two complexes with J = −1.74 cm⁻¹, g = 2.26 for 1 and J = −0.10 cm⁻¹, g = 1.67 for 2. Index abstract  Two mental-organic frameworks, namely [CoL(bpp)] _n (1) and [MnL(bipy)] _n ·0.25nH₂L·0.5nH₂O (2) (H₂L = 1,3-adamantanediacetic acid, bpp = 1,3-bis(4-pyridyl)propane, bipy = 4,4′-bipyridine), have been synthesized based on 1,3-adamantanediacetic acid and N-donor coligand with metal ions Co(II) and Mn(II). The magnetic measurement of the two polymers reveals typical antiferromagnetism exchange. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Hydrothermal synthesis,crystal structure and magnetic properties of a new one-dimensional polymer [{Cu(4,4′- bipy)(CH<Subscript>3</Subscript>COO)<Subscript>2</Subscript>}·3H<Subscript>2</Subscript>O]<Subscript>n</Subscript>

One new metal – organic coordination framework formulated as [{Cu(4,4′-bipy)(CH₃COO)₂}·3H₂O]_n (1) (where 4,4′-bipy=4,4′-bipyridine) has been hydrothermally synthesised and characterised by elemental analysis, IR and electronic spectroscopy, variable temperature magnetic moment measurement and single crystal X-ray diffraction study. Single crystal X-ray analysis reveals that 1 is one dimensional polymeric compound in which acetate ligand shows both mono- and bidentate bonding mode, and 4,4′-bipy acts as bridging ligand which supports the formation of infinite chains. The global feature of the χ _M T vs. T curve in 1 is characteristic of moderate antiferromagnetic interaction and the best fit parameters from 300 down to 2 K are found as J = −78.7 cm⁻¹.     

A New Rare-Earth Metal Coordination Polymer Constructed from <Emphasis Type="Italic">N</Emphasis>-hetero Aromatic Multicarboxylate Ligand

Abstract  

The hydrothermal reaction of Gd(NO₃)₃·6H₂O with 2,2′-bipyridyl-4,4′-dicarboxylic acid(H₂BPDC) ligand results in the formation of a new Gd(III) polymer: {[Gd₂(BPDC)₃(H₂O)₃]·H₂O} _n..(1). The central gadolinium ion is coordinated by eight oxygen atoms to give a dicapped triangular prism geometry. Based on the versatile coordination modes of BPDC²⁻ ligand, together with hydrogen bonds and π···π stacking interactions, a 3-D network is presented. DFT calculation was executed to probe the electronic structure of 1.     

Synthesis and crystal structures of 3D supramolecular compounds: [ M (4,4′-bipy)2(H2O)4] · (4,4′-bipy)2 · (3,5-daba)2 · 8H2O ( M =Zn,Mn)

Two new supramolecular compounds [M(4,4′-bipy)₂ (H₂O)₄] ·?(4,4′-bipy)₂ ·?(3,5-daba)₂ ·?8H₂O (M=Zn(1) or Mn(2), 4,4′-bipy =?4,4′-bipyridine, 3,5-daba =?3,5-diaminobenzoic acid anion) were synthesized and characterized by elemental analysis and X-ray crystal diffraction. In [M(4,4′-bipy)₂(H₂O)₄]²⁺, the M(II) is coordinated by two nitrogen atoms from two 4,4′-bipy molecules and four oxygen atoms from four waters to form an octahedral configuration. There exist uncoordinated 4,4′-bipy molecules, 3,5-diaminobenzolate counterions and water guests in the compounds. The 3D structures of the title supramolecular compounds are constructed by rich hydrogen bonds among [M(4,4′-bipy)₂(H₂O)₄]²⁺, uncoordinated 4,4′-bipy molecules, water molecules and 3,5-daba, containing a diverting hexa-member water ring.     

Self-assembly of reduced molybdophosphate-based supramolecular architectures and the study of their magnetic properties

Reduced molybdophosphate-based supramolecular compounds, such as (4,4′-H₂bipy)[Co(H₂O)₂]₂[Co(H₂PO₄)₂(HPO₄)₄(PO₄)₂(MoO₂)₁₂(OH)₆] · 17H₂O (1), [Co(2,2′-bipy)₂(H₂O)]₄[Co(H₂O)₂][Co(HPO₄)₆(PO₄)₂(MoO₂)₁₂(OH)₆] · 2H₂O (2), and [Co(2,2′-bipy)₂(H₂O)]₄[Co(H₂PO₄)(H₂O)₂]₂[Co(HPO₄)₆(PO₄)₂(MoO₂)₁₂(OH)₆] · 8H₂O (3) (4,4′-bipy=4,4′-bipyridine, 2,2′-bipy=2,2′-bipyridine), have been synthesized under hydrothermal conditions and characterized. Compound 1 exhibits a three-dimensional supramolecular twofold interpenetrating architecture built up of one-dimensional [P₄Mo₆]-based infinite covalent chains and free 4,4′-bipy molecules. Compound 2 also shows a three-dimensional supramolecular network constructed from one-dimensional covalent [P₄Mo₆]-based chains. Unlike compounds 1 and 2, compound 3 exhibits an interesting three-dimensional ‘honeycomb-like’ supramolecular network constructed by the stacking of [Co(2,2′-bipy)₂(H₂O)] units with one-dimensional channels, in which the [P₄Mo₆]-based polyoxometalate chains are located. The magnetic properties of compounds 2 and 3 are reported. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis,crystal structures,and magnetic properties of three isomorphous helical coordination polymers

Three isomorphous coordination polymers of general formula {[M(H₂bna)·(DMF)₂·(H₂O)₂]·DMF}_n (M = Co for 1, Mn for 2, Ni for 3, respectively, where H₄bna = 2,2′-dihydroxy-[1,1′]-binaphthalene-3,3′-dicarboxylate) were synthesized under solvothermal conditions and characterized by FTIR, single crystal X-ray diffraction, thermogravimetric analysis, and X-ray power diffraction analysis. All three polymers crystallize in the same monoclinic space group P2₁/n. The complexes are assembled into 1D helical chains, and each adjacent helical chain of the same chirality is further connected to form a chiral layer by hydrogen bond interactions. The layers are packed in alternating left-(M) and right-handed (P) chirality arrays. Magnetic studies reveal the presence of antiferromagnetic coupling interactions in complexes 1 and 2.     

Synthesis,structures and magnetic properties of three metal-organic frameworks containing manganese(II)

Two new Mn(II) coordination polymers formed with molecular formula [Mn(H₂O)₂(HBTC)·(H₂O)] 1 and [Mn(H₂O)₂(4,4′bipy)(HBTC)₂]·(H4,4′bipy)₂ 2, where BTC = 1,2,4-benzenetricarboxylate and 4,4′bipy = 4,4′bipydine, have been synthesized via hydrothermal approach and characterized by single crystal X-ray diffraction techniques. 1 is composed of Mn–H₂O–Mn 1D chains and further the chains are linked by HBTC ligands to form a 2D network in the ab plane; 2 is constructed by Mn–4,4′bipy–Mn 1D chains along the b direction with Mn²⁺ ions coordinated to H₂BTC and water as terminal ligands to form a 2D network. We also prepared a third compound with the molecular formula of [Mn(H₂O)(HBTC)·(H₂O)] which has been recently structurally reported elsewhere. The magnetic properties of the three compounds have been studied in detail under variable temperatures.     

基于2-丙基-4，5-咪唑二甲酸的锰（Ⅱ）和铜（Ⅰ）配合物的合成、晶体结构及性质研究

采用水热法合成了2个化合物{[Cu₂（Hpimdc）（4,4’-bpy）]·H₂O}_n（1）和[Mn₃（C₈H₇N₂O₄）₂·6H₂O]_n（2）（H₃pimdc=2-丙基-4,5-咪唑二甲酸,4,4’-bpy=4,4’-联吡啶）,并对2个化合物进行了红外、元素分析、晶体结构和热稳定性分析。晶体结构分析发现化合物1之中的H₃pimdc和4,4’-bpy交替与铜(Ⅰ)配位形成一维链线性铜(Ⅰ)配合物。沿a轴和（100）面去观察,2个一维链分子通过游离水连接而形成1个“U”型拓扑结构。而化合物2通过2-丙基-4,5-咪唑二甲酸链与锰(Ⅱ)连接为三维的网状结构。沿b轴方向,三维结构中存在交替的左/右手螺旋状二维结构。     

A new ZnII two-dimensional coordination polymer, {[Zn(μ-4,4′-bipy)(1,4-ndc)(H2O)2] · (H2O)} n (4,4′-bipy= 4,4′-bipyridine and 1,4-ndc=1,4-naphthalenedicarboxylate)

A 2D Zn^II(μ-4,4′-bipy) coordination polymer with 1,4-naphthalenedicarboxylate, {[Zn(μ-4,4′-bipy)(1,4-ndc)(H₂O)₂] · (H₂O)} _n , has been synthesized, characterized and studied by X-ray crystallography. The structural studies show the Zn atoms have six-coordinate geometry with a distorted octahedral environment. The 2D structure is grown by hydrogen bonds into a hybrid three-dimensional network.     

Novel Hybrids Constructed from Keggin-Polyoxometalate and Mixed Copper Complex

Abstract  Two new Keggin-polyoxometalate hybrids, {[Cu₂(4,4′-bpy)₂][PW₁₀^VIW₂^VO₄₀]}[Cu₂(obpy)₂]₄ · 2 H₂O (1) and {[Cu₄(2,2′-bpy)₄(4,4′-bpy)₃][SiW₁₂O₄₀]} · 2H₂O (2) (4,4′-/2,2′-bpy = 4,4′-/2,2′-bipyridyl, Hobpy = 6-hydroxy-2,2′-bipyridyl), were hydrothermally synthesized and structurally characterized. Gillard type hydration of 2,2′-bipy is observed during the synthesis of 1, resulting in a new obpy ligand in situ. X-ray structural analyses show that 1 consists of 1D hybrid chain {[Cu₂(4,4′-bpy)₂][PW₁₀^VIW₂^VO₄₀]}_∞ and [Cu₂(obpy)₂] dimer, whereas 2 possesses 1D hybrid structure based on Keggin-type [SiW₁₂O₄₀]⁴⁻ anions and tetra-nuclear copper complexes [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺. Both compounds present interesting supramolecular architectures based on π–π stacking and hydrogen bonds. Graphical Abstract  Compounds {[Cu₂(4,4′-bpy)₂][PW₁₂O₄₀]}[Cu₂(obpy)₂]₄ · 2H₂O (1) and [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃][SiW₁₂O₄₀] · 2H₂O (2) were hydrothermally synthesized. 1 features that the [Cu₂(obpy)₂] dimers based on in situ generated obpy ligands are stumped between the layers where 1D hybrid chain {[Cu₂(4,4′-bpy)₂][PW₁₂O₄₀]}_∞ locates, while 2 exhibits 1D chain-like structure based on anions [SiW₁₂O₄₀]⁴⁻ and tetra-copper complexes [Cu₄(2,2′-bpy)₄(4,4′-bpy)₃]⁴⁺.      

Temperature-dependent synthesis, crystal structures, characterizations, and DFT calculations of two new copper(II) complexes with p-fluorobenzoic acid and 2,2′-bipyridine ligands

Two new copper(II) complexes, [Cu(p-FBA)₂(2,2′-bpy)]·(H₂O) (1) and [Cu(p-FBA)(2,2′-bpy)₂]·(p-FBA)₂ (2) {p-FBA = p-fluorobenzoic acid, 2,2′-bpy = 2,2′-bipyridine} have been obtained from an identical starting mixture using temperature as the only independent variable and characterized by X-ray single crystal diffraction as well as with infrared spectroscopy, elemental analysis, and thermogravimetric analysis. The results reveal that 1 has 1D infinite chain structure formed by O–H···O hydrogen bonds, while 2 features a 0D structure. Additionally, there exist C–H···O hydrogen bonds and π–π stacking interactions in 1, forming 2D supramolecular structure. Furthermore, density functional theory (DFT) calculations of the structures, stabilities, orbital energies, composition characteristics of some frontier molecular orbitals and Mulliken charge distributions of the [Cu(p-FBA)₂(2,2′-bpy)] of 1 and [Cu(p-FBA)(2,2′-bpy)₂]⁺ cation of 2 were performed by means of Gaussian 03W package and taking B3LYP/lanl2dz basis set.     

基于2-丙基-4,5-咪唑二甲酸的锰(Ⅱ)和铜(Ⅰ)配合物的合成、晶体结构及性质研究(英文)

采用水热法合成了2个化合物{[Cu2(Hpimdc)(4,4′-bpy)]·H2O}n(1)和[Mn3(pimdc)2·6H2O]n(2)(H3pimdc=2-丙基-4,5-咪唑二甲酸,4,4′-bpy=4,4′-联吡啶),并对2个化合物进行了红外、元素分析、晶体结构和热稳定性分析。晶体结构分析发现化合物1之中的H3pimdc和4,4′-bpy交替与铜(Ⅰ)配位形成一维链线性铜(Ⅰ)配合物。沿a轴和(100)面去观察,2个一维链分子通过游离水连接而形成1个"U"型拓扑结构。而化合物2通过2-丙基-4,5-咪唑二甲酸链与锰(Ⅱ)连接为三维的网状结构。沿b轴方向,三维结构中存在交替的左/右手螺旋状二维结构。     

Synthesis,structure, and character of two rare earth carboxylic acid complexes

Two rare earth carboxylic acid complexes, [Sm(MeBA)₃(2,2′-bipy)]₂·2(2,2′-bipy) (MeBA = 3-methylbenzoic acid; 2,2′-bipy = 2,2′-bipyridine) (1) and [Pr(MeBA)₃(H₂O)₂]_n?n(4,4′-bipy) (4,4′-bipy = 4,4′-bipyridine) (2), have been synthesized under hydrothermal conditions and structurally determined by single-crystal X-ray diffraction. Compound 1 is a dimer and further assembles into an infinite chain, two-dimensional net and three-dimensional supramolecular structure via weak π–π and C–H···π interactions. Some 2,2′-bipy coordinates with Sm and some exist by non-covalent C–H···π interactions. Compound 2 is a 1D infinite chain structure, with adjacent 1D chains connected into a 2D layer structure by O–H···N hydrogen bonds. The two complexes were characterized by elemental analyses, IR, photoluminescence, and TGA. In order to illustrate subtle structural characteristics of intermolecular interactions and magnetic sensitivity of the complex, 2D-IR correlation spectra (2D-IR COS) under magnetic perturbation for 1 were performed.     

Syntheses,structures, and properties of four coordination compounds constructed from asymmetric semi-rigid V-shaped multicarboxylate ligand

Four new compounds, [Mn(HL)(phen)₂(H₂O)] (1), [Ni(HL)(phen)₂(H₂O)] (2), [Zn(HL)(4,4′-bipy)_1.5(H₂O)] _n ?·?2nH₂O (3) and [Zn₂(HL)₂(H₂O)₆] (4), have been synthesized from an asymmetric semi-rigid V-shaped multicarboxylate 4-(4-carboxy-phenoxy)-phthalic acid (H₃L) with 1,10-phenanthroline (phen), or 4,4′-bipyridine (4,4′-bipy) as auxiliary ligands. Single-crystal X-ray diffraction analysis reveals that 1, 2 and 4 have 0-D structures with 3-D supramolecular frameworks formed by intermolecular hydrogen bonds. Compound 3 shows a 1-D infinite ribbon bridged by 4,4′-bipy, which further forms a 3-D supramolecular architecture by π–π stacking interactions and hydrogen bonds. Thermal stabilities of 1–4 and luminescence properties of 3 and 4 have also been investigated.     

Two Novel Organic–Inorganic Hybrid Compounds Constructed from Anderson-type Clusters and Transition-Metal Complexes

Abstract  Two organic–inorganic hybrid compounds based on the Anderson-type clusters [TeMo₆O₂₄]⁶⁻, [(H₂O)₂Co(TeMo₆O₂₄)][(C₁₀N₂H₁₀)₂] · 9.5H₂O (1), [(C₁₀N₂H₉)Ni(H₂O)₃]₂[TeMo₆O₂₄] · 8.5H₂O (2), have been synthesized by hydrothermal reactions and characterized by elemental analyses, IR spectra, thermal stability analyses, and single-crystal X-ray diffraction. Compound 1 displays a 1D chain structure constructed from alternating [TeMo₆O₂₄]⁶⁻clusters and Co²⁺ along the a axis with two pendant ligands 4,4′-bpy (4,4′-bipyridine). Compound 2 is composed of [TeMo₆O₂₄]⁶⁻ clusters coordinated by [Ni(bpy)(H₂O)₃]²⁺ moieties, and a supramolecular architecture is further formed through extensive hydrogen bonds interactions. Graphical Abstract  Two organic–inorganic hybrid compounds based on the Anderson-type clusters [TeMo₆O₂₄]⁶⁻and the unit [M(4,4′-bpy)] have been synthesized under the hydrothermal conditions. Compound 1 displays a 1D chain structure constructed covalently from alternating polyoxoanions [TeMo₆O₂₄]⁶⁻ and Co²⁺ along the a axis with two pendant ligands 4,4′-bipyridine. Compound 2 is composed of [TeMo₆O₂₄]⁶⁻ polyoxoanion coordinated by [Ni(bpy)(H₂O)₃]²⁺ moieties and shows a 1D chain structure through the hydrogen bonds interactions. Electronic supplementary material  The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Synthesis, characterization and properties of β-octamolybdate-supported transition metal complexes with mixed ligands: [Cu(2,2′-bipy)(C6H5NO2)(H2O)]2[Mo8O26]·5H2O

A novel organic–inorganic hybrid compound [Cu(2,2′-bipy)(C₆H₅NO₂)(H₂O)]₂[Mo₈O₂₆]·5H₂O (1), (2,2′-bipy = 2,2′-bipyridine; C₆H₅NO₂ = pyridine-4-carboxylic acid) has been prepared and characterized by elemental analyses, IR spectrum, thermal stability analysis, and single-crystal X-ray diffraction. Compound 1 is a discrete cluster, constructed from β-[Mo₈O₂₆]⁴⁻ subunits covalently bonded to two [Cu(2,2′- bipy)(C₆H₅NO₂)(H₂O)]₂⁴⁺ coordination cations via terminal oxo groups that connect one molybdenum site. A 3D supramolecular network is further formed by extensive hydrogen bonding interactions and π–π interactions of the 2,2′-bipy and pyridine-4-carboxylic acid ligands. EPR and magnetic susceptibility studies have been used to elucidate the electronic properties of the Cu²⁺ centres, and the results are in good agreement with the structural features of the compound.