Synthesis and Characterization of a Novel Binuclear Cobalt(II) Complex with Discrete Water Clusters (H2O)8

A new octameric water cluster was observed in the complex Co₂(dptc)(bipy)₂(H₂O)₆ · 4H₂O ( 1 ) (H₄dptc = diphenyl‐3,3′,4,4′‐tetracarboxylic acid; bipy = 2,2′‐bipyridine), which was characterized by single‐crystal X‐ray diffraction, elemental analysis and IR spectroscopy. The centrosymmetric octamer consists of a water hexamer in the chair form and two water molecules and brings to light a novel mode of the cooperative association of water molecules. Those complex units are connected into a 2D infinite layer framework through hydrogen bonding. Consequently, the 2D layers are further aggregated by hydrogen bonding with octameric subunits and π ··· π stacking interactions to form a 3D supramolecular architecture.     

Cobalt(III) Complexes of D‐Galactosylamine

The β‐pyranose isomer of D ‐galactosylamine ( 1 ) formed complexes with three different cobalt(III) fragments. Crystals containing the dication [Co(tren)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 3 ) showed coordination through the anomeric amino group (N1) and the deprotonated hydroxy group (O2) of the ⁴C₁ β‐pyranose form, which is also the major isomer of free galactosylamine. The cationic complexes [Co(fac‐dien)(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 4 ) and [Co(phen)₂(β‐D ‐Galp1N2H_–1‐κ²N¹,O²)]²⁺ ( 5 ) were analysed by NMR spectroscopy and showed the same coordination mode as 3 . In terms of available ligand isomers it was shown that 1 exhibits an anomeric equilibrium in solution of both pyranose and both furanose forms as is typical for the parent glycose, galactose.     

Synthesis and Crystal Structures of Novel Copper(I) Clusters with Bridging Silyl Amide Ligands

Treatment of copper(I) chloride with R₂Si(NLiPh)₂ (R = Me, Ph) in thf led to the formation of the octanuclear cluster compounds [Cu₈{(R₂Si(NPh)₂}₄] [R = Me ( 1 ), Ph ( 2 ).] Compound 1 crystallizes in the tetragonal space group P4/n, with a = 1505.41(5) and c = 1911.32(7) pm. The X‐ray crystal structure determination revealed a cube shaped Cu₈ cluster core with μ₄ bridging Me₂Si(NPh)₂^2– ligands. The copper atoms display an almost linear coordination with Cu–N distances in the range of 191.1(3)–191.4(3) pm. The Cu–Cu distances are 265.7(1)–267.3(1) pm. Compound 2 forms monoclinic crystals, space group P2₁/n, with a = 1461.87(4), b = 2483.77(6), c = 2725.49(8) pm, β = 100.77(1)°. The cluster core of compound 2 consists formally of two mutually perpendicular arranged trigonal prisms, which share a common square face. Like in the case of compound 1 the square faces of the cluster core are capped by μ₄ bridging Ph₂Si(NPh)₂^2– ligands. The copper atoms adopt a nearly linear N–Cu–N coordination with Cu–N distances of 190.0(4)–195.1(4) pm. The Cu–Cu distances are 252.3(1)–305.6(1) pm.     

Infinite Coordination Polymers of One‐ and Two‐dimensional Cobalt Acetates

Two coordination polymers of cobalt acetate, [Co₅(O₂CMe)₁₀] ( 1 ) and [Co(O₂CMe)₂(H₂O)] · H₂O ( 2 ), were solvothermally synthesized and characterized by single‐crystal and powder X‐ray diffraction analyses, IR spectroscopy, and elemental analysis. Compound 1 crystallizes in orthorhombic space group Pbcn in two‐dimensional layers, which consist of 12‐membered cobalt rings. Compound 2 crystallizes in monoclinic space group C2/m and exhibits one‐dimensional chains, which are bridged by one water molecule and two acetate ligands in (2.11)‐ and (2.20)‐modes. Preliminary magnetic studies revealed that antiferromagnetic couplings exist in both compounds.     

Crystal Structure and Magnetic Properties of Copper(II) and Nickel(II) Binuclear Complexes with Bisacylhydrazones Based on 2,6‐Diformyl‐4‐methylphenol

The series of binuclear Cu(II) and Ni(II) complexes with an asymmetrical exchange fragment based on 2,6‐diformyl‐4‐methylphenol bishydrazone has been synthesized for the first time. The compositions and structures of both ligands and its complexes have been established with the data of IR, ¹H NMR, and extended X‐ray absorption fine structure (EXAFS) spectroscopical studies as well as magnetic measurements. The structure of [Ni₂L₃(μ‐Pz)] · 2CH₃OH (L = triply deprotonated form of bishydrazone, Pz = pyrazol) was confirmed by X‐ray crystallographic analysis. In this complex, the coordination environment of two nickel ions is quite different, one nickel atom is square‐planar and the other is distorted octahedral coordinated. The values of exchange parameter calculated in terms of HDVV theory have been compared with the features of an asymmetrical exchange fragment's electronic and geometrical structure.     

One‐dimensional Salen‐type Chain‐like Lanthanide(III) Coordination Polymers: Syntheses,Crystal Structures,and Fluorescence Properties

Four salen‐type lanthanide(III) coordination polymers [LnH₂L(NO₃)₃(MeOH)_x]_n [Ln = La ( 1 ), Ce ( 2 ), Sm ( 3 ), Gd ( 4 )] were prepared by reaction of Ln(NO₃)₃ · 6H₂O with H₂L [H₂L = N,N′‐bis(salicylidene)‐1,2‐cyclohexanediamine]. Single‐crystal X‐ray diffraction analysis revealed that H₂L effectively functions as a bridging ligand forming a series of 1D chain‐like polymers. The solid‐state fluorescence spectra of polymers 1 and 2 emit single ligand‐centered green fluorescence, whereas 3 exhibits typical red fluorescence of Sm^III ions. The lowest triplet level of ligand H₂L was calculated on the basis of the phosphorescence spectrum of Gd^III complex 4 . The energy transfer mechanisms in the lanthanide polymers were described and discussed.     

A New Family of Trinuclear Nickel(II) Complexes as Single‐Molecule Magnets

Three new trinuclear nickel (II) complexes with the general composition [Ni₃L₃(OH)(X)](ClO₄) have been prepared in which X=Cl^? ( 1 ), OCN^? ( 2 ), or N₃^? ( 3 ) and HL is the tridentate N,N,O donor Schiff base ligand 2‐[(3‐dimethylaminopropylimino)methyl]phenol. Single‐crystal structural analyses revealed that all three complexes have a similar Ni₃ core motif with three different types of bridging, namely phenoxido (μ₂ and μ₃), hydroxido (μ₃), and μ₂‐Cl ( 1 ), μ_1,1‐NCO ( 2 ), or μ_1,1‐N₃ ( 3 ). The nickel(II) ions adopt a compressed octahedron geometry. Single‐crystal magnetization measurements on complex 1 revealed that the pseudo‐three‐fold axis of Ni₃ corresponds to a magnetic easy axis, being consistent with the magnetic anisotropy expected from the coordination structure of each nickel ion. Temperature‐dependent magnetic measurements indicated ferromagnetic coupling leading to an S=3 ground state with 2J/k=17, 17, and 28 K for 1 , 2 , and 3 , respectively, with the nickel atoms in an approximate equilateral triangle. The high‐frequency EPR spectra in combination with spin Hamiltonian simulations that include zero‐field splitting parameters D_Ni/k=?5, ?4, and ?4 K for 1 , 2 , and 3 , respectively, reproduced the EPR spectra well after a anisotropic exchange term was introduced. Anisotropic exchange was identified as D_i,j/k=?0.9, ?0.8, and ?0.8 K for 1 , 2 , and 3 , respectively, whereas no evidence of single‐ion rhombic anisotropy was observed spectroscopically. Slow relaxation of the magnetization at low temperatures is evident from the frequency‐dependence of the out‐of‐phase ac susceptibilities. Pulsed‐field magnetization recorded at 0.5 K shows clear steps in the hysteresis loop at 0.5–1 T, which has been assigned to quantum tunneling, and is characteristic of single‐molecule magnets.     

Copper(I) Clusters with Trifunctional Silyl Amide Ligands. Synthesis and Crystal Structures of [Li(THF)4]2[Cu10{RSi(NPh)3}4] (R = Me,Ph, Vin)

Treatment of CuCl with the lithiated silyl amides RSi(NLiPh)₃ (R = Me, Ph, Vin) in THF as solvent led to the formation of the novel Cu^I cluster compounds [Li(THF)₄]₂[Cu₁₀{RSi(NPh)₃}₄]. For each of the three compounds the X‐ray crystal structure analysis revealed similar Si₄N₁₂Cu₁₀ cores which are based on cubane like Cu₈ cores bearing two additional peripheral copper atoms. The copper atoms are coordinated nearly linearly by the μ₅‐bridging silyl amide ligands with Cu–N distances in the range of 187.1(3) to 194.5(4) pm and N–Cu–N angles of 171.6(1) to 178.7(1)°. For each of the compounds the structural parameters are very similar which indicates that the structures are barely influenced by the different steric requirements of the organic groups bound to silicon.     

Novel Copper(I) Clusters with 2‐(Diphenylphosphanyl)anilide Ligands. Synthesis and Crystal Structures of [Cu6X2(NHR)4] (X = Cl,Br, I; R = C6H4‐2‐PPh2)

Treatment of copper(I) halides CuX (X = Cl, Br, I) with lithium 2‐(diphenylphosphanyl)anilide [Li(HL)] in THF led to the formation of hexanuclear copper(I) complexes [Cu₆X₂(HL)₄] [X = Cl ( 1 ), Br ( 2 ), I ( 3 )]. In compounds 1 – 3 , the copper atoms are in a distorted octahedral arrangement and the amide ligands adopt a μ₃‐κP,κ²N bridging mode. Additionally there are two μ₂‐bridging halide ligands. Each of the [Cu₆X₂(HL)₄] clusters comprises two copper atoms, which are surrounded by two amide nitrogen atoms in an almost linear coordination [Cu–N: 186.2(3)–188.0(3) pm] and four copper atoms, which are connected to an amide N atom, a P atom, and a halogen atom in a distorted trigonal planar fashion [Cu–N: 199.6(3)–202.3(3) pm)].     

Three Novel 1‐H‐Benzimidazole‐5‐Carboxylate‐Based Nickel(II)/Cobalt(II) Coordination Polymers: Synthesis,Crystal Structures,Luminescent, and Magnetic Properties

Three 1H‐benzimidazole‐5‐carboxylate (Hbic^–)‐based coordination polymers, {[Ni(H₂O)(Hbic)₂] · 2H₂O}_n ( 1 ), {[Ni(H₂O)₂(Hbic)₂] · 3H₂O}_n ( 2 ), and {[Co₂(H₂O)₄(Hbic)₄] · 4DMF · 3H₂O}_n ( 3 ) were obtained by reactions of the ligand H₂bic and Ni^II or Co^II salts in the presence of different structure directing molecules. They were structurally characterized by single‐crystal X‐ray diffraction, IR spectra, elemental analysis, thermal stability, luminescent, and magnetic measurements. Structural analysis suggests that the three polymers exhibit a 2D (4, 4) layer for 1 and 1D linear double chains for both 2 and 3 due to the variable binding modes and the specific spatial orientation of the Hbic^– ligand towards the different paramagnetic metal ions, which were further aggregated into different 3D supramolecular architectures by popular hydrogen‐bonding interactions. Weak and comparable antiferromagnetic couplings mediating by Hbic^– bridge are observed between the neighboring spin carriers for 2 and 3 , respectively. Additionally, complexes 1 – 3 also display different luminescence emissions at room temperature due to the ligand‐to‐metal charge transfer.     

A New Two‐Dimensional Manganese(II) Coordination Polymer Constructed from Trinuclear Molecular Building Block: Syntheses,Structure and Magnetic Property

A new manganese(II) coordination polymer, [Mn₃(atpt)₃(2, 2′‐bpy)₂]_n ( 1 ) (H₂atpt = 2‐aminoterephthalic acid; 2, 2′‐bpy = 2, 2′‐bipyridine), was synthesized by hydrothermal reaction of Mn(OAc)₂, H₂atpt, and 2, 2′‐bpy. It was structurally characterized by element analysis, IR spectroscopy, powder XRD, and magnetic measurements. X‐ray single‐crystal analysis was carried out for 1 , which crystallizes in the orthorhombic system, space group Pbca. The single X‐ray diffraction studies reveal that 1 consists of infinite layers of alternating trinuclear manganese subunits and H₂atpt ligands. There are two types of different coordination modes of H₂atpt in 1 . Magnetic susceptibility data for 1 were measured in the range 3–300 K. There are antiferromagnetic interactions between manganese ions of 1 .     

Synthese und Eigenschaften von Triphenylzinnmolybdaten mit kettenförmigen Anionen des Typs 1∞[(Ph3Sn)MoO4]–. Die Kristallstrukturen von (nPr4N)[(Ph3Sn)MoO4]·CH3CN, (nBu4N)[(Ph3Sn)MoO4], [Zn(en)2(Ph3Sn)2(MoO4)2]·2DMF·EtOH und [Cu(en)2(Ph3Sn)2(MoO4)2]·2DMF·EtOH

The reaction of Ph₃SnCl, (R₄N)₂[Mo₆O₁₉] and (R₄N)OH in a molar ratio of 6:1:10 leads to the formation of (R₄N)[(Ph₃Sn)MoO₄] (R = ⁿPr ( 1 ), ⁿBu ( 2 )). Compounds 1· CH₃CN and 2 have been charactarized by IR spectroscopy and single crystal X‐ray diffraction. 1· CH₃CN forms orthorhombic crystals, space group P2₁2₁2₁ with a = 1339.9(2), b = 1508.9(2), c = 1733.2(3) pm. 2 crystallizes in the monoclinic space group P2₁ with a = 1342.6(2), b = 2280.3(4), c = 1344.0(2) pm, β = 118.34(1). Both compounds 1 and 2 consist of isolated R₄N⁺ cations and polymeric $\rm^{1}_{\infty}$ [(Ph₃Sn)MoO₄]^– chains with an alternating arrangement of Ph₃Sn⁺ and MoO₄^2– groups. Treatment of (Ph₃Sn)₂MoO₄ with bis(ethylenediamine)copper(II) succinate yields [Cu(en)₂(Ph₃Sn)₂(MoO₄)₂] ( 3 ). The zinc derivative [Zn(en)₂(Ph₃Sn)₂(MoO₄)₂] ( 4 ) is obtained similarly by reaction of (Ph₃Sn)₂MoO₄ with bis(ethylenediamine)zinc(II) formiate. Compounds 3· 2DMF · EtOH and 4· 2DMF · EtOH crystallize in the monoclinic space group P2₁/n with a = 1998.0(2), b = 1313.3(1), c = 2181.6(2) pm, β = 90.97(1)° for 3 and a = 2015.4(1), b = 1316.7(1), c = 2157.0(1) pm, β = 90.40(1)° for 4 . Like in the cases of 1 and 2, polymeric $\rm^{1}_{\infty}$ [(Ph₃Sn)MoO₄]^– chains are observed. The [M(en)₂]²⁺ units (M = Cu, Zn) act as linkers between the $\rm^{1}_{\infty}$ [(Ph₃Sn)MoO₄]^– chains to give 2D layer structures with (6, 3) net topology.     

Dimorphic Modification of the Trinuclear Nickel(II) Complex [Ni3(NCS)6(pdz)6]: Synthesis,Crystal Structure,Thermal, Magnetic and Spectroscopic Properties

Reaction of nickel(II) thiocyanate and pyridazine (pdz) as organic spacer ligand leads to the formation of the ligand‐rich 1:2 (1:2 = metal to ligand ratio) trinuclear nickel(II) complex of composition [Ni₃(NCS)₆(pdz)₆]. Depending on the reaction solvent, different polymorphic modifications are obtained: Reaction in acetonitrile leads to the formation of the new modification 1I and reaction in ethanol leads to the formation of modification 1II reported recently. In their crystal structures discrete [Ni₃(NCS)₆(pdz)₆] units are found, in which each of the Ni²⁺ cations exhibits a NiN₆ distorted octahedral arrangement. The central Ni²⁺ cation is coordinated by four bridging pdz ligands and two thiocyanato anions in trans positions. Both thiocyanato anions exhibit the end‐on bridging mode. The peripheral Ni²⁺ cations are bridged by one thiocyanato anion and by two pdz ligands with the central Ni²⁺ cation. Further they are coordinated by two terminal N‐bonded thiocyanato anions and one terminal N‐bonded pdz ligand. The structure of 1I was determined by X‐ray single crystal structure investigation and emphasized by infrared spectroscopy. Magnetic measurements revealed a quasi Curie behavior with net ferromagnetic interactions for 1I and net antiferromagnetic interactions for 1II . Solvent‐mediated conversion experiments clearly show that modification 1I represents the thermodynamic most stable form at room temperature and that modification 1II is metastable. On thermal decomposition, both modification transform quantitatively in a new ligand‐deficient intermediate. Elemental analysis revealed a 3:4 compound of composition [Ni₃(NCS)₆(pdz)₄]. A structure model supported by IR spectroscopic investigations was assumed, in which three coordination modes of the thiocyanato anion exist, resulting in a 2D polymeric network.     

Synthesis of Lanthanide Coordination Polymers with Benzophenone-4,4′-dicarboxylate： Effect of Lanthanide Contraction on Structures

Four lanthanide coordination polymers with benzophenone‐4,4′‐dicarboxylic acid (H₂bpndc) and 1,10‐phenanthroline (phen), [Ln₂(bpndc)₃(phen)] (Ln=La (1), Pr (2) and Tb (3)), [Yb(bpndc)₁₅(phen)].05H₂O (4) were obtained through solvothermal synthesis. The crystallographic data show that 1, 2, and 3 are isostructural, the Ln(III) ions in 1, 2 and 3 are all eight‐ and ten‐coordinated, respectively, and thus the Ln(III) ions are connected by bpndc ligands, resulting in an interpenetrating 3D structure. While in 4, the Yb(III) ions are eight‐coordinated and connected by bpndc ligands into a 3D structure with 1D rhombic channels, which result from the effect of lanthanide contraction from La(III) to Yb(III) ions, and the bpndc ligands in 1, 2, 3, and 4 display three types of coordination modes.     

Self‐Assembly and Structure of Cobalt(II) Complexes Using Diaminodiamide Ligands

The self‐assembly of Co(II) with two diaminodiamide ligands, 4,7‐diazadecanediamide and 4,8‐diazaundecanediamide, gave two different crystals, [(C₈H₁₈N₄O₂)Co(OH)₂Co(C₈H₁₈N₄O₂)]Cl₂ ( 1 ) [Co(C₉H₂₀N₄O₂)(Cl)(H₂O)]·Cl·2H₂O ( 2 ). Structures of 1 and 2 were characterized by single‐crystal X‐ray diffraction analysis. Structural data for 1 shows a novel type of binuclear complex with distorted octahederal coordination geometry around the Co atoms through the hydroxo bridges. By using inter‐connector N‐H···N hydrogen bonding interactions as building forces, each cationic moiety [(C₈H₁₈N₄O₂)Co(OH)₂Co(C₈H₁₈N₄O₂)]²⁺ is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chain‐like structure. The chains are further connected into a 2D layer in a (4,4)‐topology via N‐H···Cl_free hydrogen‐bonding interactions. Structural data for 2 indicate that the cobalt atom adopts a six‐coordinated N₂O₄ environment, giving a distorted octahedral geometry, where two N‐ and two O‐donor sets of ligand located at equatorial positions and one water and one chloride occupied at axial positions. Through NH···Cl‐Co and OH···Cl‐Co contacts, each cationic moiety [Co(C₉H₂₀N₄O₂)(Cl)(H₂O)]⁺ in 2 is linked to neighboring ones, producing a charged hydrogen‐bonded 1D chainlike structure. Thus, the crystal‐engineering approach has proved successful in the solid‐state packing due to steric strain effect of the diaminodiamide ligand.     

Simplified Synthesis and Structural Study of { Ta6Br12} Clusters

Direct reaction of stoichiometric amounts of KBr, tantalum and bromine at 720 °C, followed by extraction and crystallization gives Ta₆Br₁₄ · 7H₂O (1) . This compound slowly aquates into [(Ta₆Br₁₂)(H₂O)₆]²⁺, which crystallized as mixed Cs⁺/Br^– ( 2 ), Cl^– ( 3 ) and SO₄^2– ( 4 ) salts. In Bu₄NBr melt, 1 undergoes oxidation into (Bu₄N)₂[(Ta₆Br₁₂)Br₆] ( 5 ). Reaction of 1 with dimethylsulfoxide also induces oxidation of the { Ta₆Br₁₂} ²⁺ core into { Ta₆Br₁₂} ⁴⁺, and the corresponding complex [(Ta₆Br₁₂)(dmso)₂Cl₄] · iPrOH · 4.8H₂O ( 6 ) was isolated and structurally characterized. Molecular and crystal structures for 2 – 6 were determined.     

Neue [{Cp(CO)2Mo}2ESbCl]‐Cluster mit tetraedrischem Mo2SbE‐Gerüst (E = S,Se)

Reaction of [{Cp(CO)₃Mo}₂SbCl] with S₈ or Se₈ leads to the formation of cluster compounds [{Cp(CO)₂Mo}₂ESbCl] (E = S, Se). [{Cp(CO)₂Mo}₂SSbCl] crystallizes monoclinic, space group P2₁/n with a = 812.28(3), b = 855.65(4), c = 2441.01(9) pm and β = 90.149(3)°; [{Cp(CO)₂Mo}₂SeSbCl] · CH₂Cl₂ crystallizes triclinic, space group P$\bar{1}$ with a = 828.82(9), b = 1002.8(1), c = 1340.0(2) and α = 109.24(1), β = 100.87(1), γ = 96.81(1)°. For both compounds X‐ray crystal structure analysis reveals tetrahedral Mo₂SbE cluster cores with Sb–E bond lengths of 256.8(1) pm (E = S) and 265.3(1) (E = Se). According to the 18 electron rule the [{Cp(CO)₂Mo}₂ESbCl] clusters can be regarded as complexes of the 4 electron donator ESbCl that is coordinated “side‐on” to a {Cp(CO)₂Mo}₂ fragment.     

Construction of Mononuclear Copper(II) and Trinuclear Cobalt(II) Complexes Based on Asymmetric Salamo‐Type Ligands

Mononuclear copper(II) and trinuclear cobalt(II) complexes, namely [Cu(L¹)]₂ · CH₂Cl₂ and [{Co(L²)(EtOH)}₂Co(H₂O)] · EtOH {H₂L¹ = 4,6‐dichloro‐6′‐methyoxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol and H₃L² = 6‐ethyoxy‐6′‐hydroxy‐2,2′‐[1,1′‐(ethylenedioxydinitrilo)dimethylidyne]diphenol}, were synthesized and characterized by elemental analyses, IR and UV/Vis spectroscopy, and single‐crystal X‐ray diffraction. In the Cu^II complex, the Cu^II atom is four‐coordinate, with a N₂O₂ coordination sphere, and has a slightly distorted square‐planar arrangement. Interestingly, the obtained trinuclear Co^II complex is different from the common reported 2:3 (L:Co^II) salamo‐type Co^II complexes. Infinite 2D layer supramolecular structures are formed via abundant intermolecular hydrogen bonding and π ··· π stacking interactions in the Cu^II and Co^II complexes.     

Synthesis and Crystal Structures of Manganese(II) and ­Cobalt(II) Complexes with 2, 6‐Dimethoxybenzoic Acid and Additional N‐Donor Ligands

Three coordination compounds [Mn₃(dmb)₆(H₂O)₄(4, 4′‐bpy)₃(EtOH)]_n ( 1 ) and [M(dmb)₂(pyz)₂ (H₂O)₂] [M^II = Co ( 2 ), Mn ( 3 )] (Hdmb = 2, 6‐dimethoxybenzoic acid, 4, 4′‐bpy = 4, 4′‐bipyridine, pyz = pyrazine) were synthesized and characterized by single‐crystal X‐ray diffraction analysis. Compound 1 consists of infinite 1D polymeric chains, in which the metal entities are bridged by 4, 4′‐bpy ligands. There are four crystallographically independent Mn^II atoms in the linear chain with different coordination modes, which is only scarcely reported for linear polymers. The isostructural crystals of 2 and 3 are composed of neutral mononuclear complexes. In crystal the complexes are combined into chains by intermolecular O–H ··· N hydrogen bonds and π–π interactions between antiparallel pyrazine molecules.     

Synthesis and Magnetic Properties of Two New Cobalt Complexes Constructed by Semirigid V‐shaped 5‐(4‐Carboxyphenoxy)‐pyridine‐2‐carboxylic Acid

Two cobalt complexes, [Co₃(L)₂(CH₃OH)₂(μ₃‐OH)₂] ( 1 ) and [Co(L)(bpe)_0.5] · H₂O ( 2 ) [H₂L = 5‐(4‐carboxyphenoxy)‐pyridine‐2‐carboxylic acid; bpe = 1, 2‐bis(4‐pyridyl)ethylene] were synthesized and fully characterized by elemental analyses, IR spectroscopy, single‐crystal X‐ray diffraction, thermogravimetric analysis (TGA), and magnetic analysis. Complex 1 has a two‐dimensional (2D) structure with puckered Co–O–Co chains, and 2 displays a three‐dimensional (3D) network containing one‐dimensional rectangular channels with dimensions of 9.24 × 13.84 Å. In complex 1 , variable‐temperature magnetic susceptibility measurements indicate antiferromagnetic interactions between cobalt magnetic centers.