A New 3D Manganese(II) Coordination Polymer with 4,4‐Dicarboxy‐2,2′‐bipyridine and 1,10‐Phenanthroline: Synthesis,Structural, and Magnetic Properties

A new 3D Mn^II metal‐organic framework compound {Mn(phen)(dcbp)}_n (H₂dcbp = 4,4‐dicarboxy‐2,2′‐bipyridine, phen = 1,10‐phenanthroline) was isolated under hydrothermal conditions and structurally characterized. In the compound, the dcbp ligand is deprotonated to give a neutral species (metal:ligand with 1:1 stoichiometry). Along the c axis, the neighboring Mn^II ions are linked by two carboxylate bridges in µ₂‐coordinating mode to generate a 1D zigzag chain, and these chains are interlinked by dicarboxylate groups of long dcbp ligands to generate a 3D (4,4)‐connected structure with the (4².8⁴) net topology. IR and UV/Vis spectroscopy and variable temperature magnetic susceptibility measurements were made, which indicated weak antiferromagnetic interactions between the Mn^II ions of the compound.     

A 1,2,4‐Triazole‐based Polynuclear Mixed‐valence MnIIMnIII Complex: Synthesis,Characterization, and Magnetic Property

A mixed‐valence Mn complex {[Mn^IIMn^III(HL)₂(4,4′‐bpy)(H₂O)₂] · (ClO₄)(DMF)₃(4,4′‐bpy)_0.5}_n ( 1 ) [H₂L = 3‐(2‐phenol)‐5‐(pyridin‐2‐yl)‐1,2,4‐triazole] was synthesized and characterized by X‐ray single‐crystal structure analysis and magnetic susceptibility. Single‐crystal X‐ray analysis revealed that complex 1 has a dinuclear core, in which adjacent central Mn^III atoms are linked by 4,4′‐bipyridine to form an infinite one‐dimensional (1D) molecular configuration. According to the Mn surrounding bond lengths and bond valence sum (BVS) calculations, we demonstrated that the Mn atom coordinated to the pyridine N atoms is in the +2 oxidation state, while another Mn atom coordinated to the phenolic oxygen atoms is in the +3 oxidation state. Magnetic susceptibility data of the complex 1 indicate that the ferromagnetic interaction dominates in this complex.     

Porous Metal‐organic Framework based on Strip‐shaped Manganese(II) Chains: Synthesis,Structure, and Magnetic Properties

The Mn^II‐based porous metal‐organic framework, [Mn₃(btca)₂(HCOO)(μ₃‐OH)(H₂O)₂] · 2DMF ( 1 ) (H₂btca = benzotriazole‐5‐carboxylate acid), was prepared by the solvothermal reaction of Mn(CH₃COO)₂ · 4H₂O and H₂btca, which was characterized by infrared spectroscopy, thermogravimetric analyses, and X‐ray crystallographic study. 1 exhibits 3D framework with 1D rectangle channels constructed by the strip‐shaped chains containing [Mn₅(μ₃‐OH)₂(btca)₄]^– pentaclusters subunits. Furthermore, the magnetic measures show that 1 exhibits weak ferromagnetic behavior at low temperature.     

pH Dependent Synthesis of Two Manganese Compounds based on 5‐(2‐Pyrimidyl)tetrazole‐1‐acetic Acid

Reactions of Hpymtza [Hpymtza = 5‐(2‐pyrimidyl)tetrazole‐1‐acetic acid] with MnCl₂ · 4H₂O under different pH conditions, afforded the complexes [Mn(pymtza)₂(H₂O)₄] ( 1 ) and [Mn₂(pymtza)₂Cl₂(EtOH)] · H₂O ( 2 ). The compounds were structurally characterized by elemental analysis, IR spectroscopy and single‐crystal X‐ray diffraction. Compound 1 shows a mononuclear structure, whereas complex 2 has a 1D chain structure. In compound 1 , the pymtza ligand only acts in a monodentate manner to coordinate to one central Mn^II atom by one carboxylate atom, In 2 , pymtza acts as tetradentate ligand to connect three Mn^II ions. Compounds 1 and 2 display 3D networks by hydrogen bonding interactions. Furthermore, the luminescence properties of Hpymtza as well as compounds 1 and 2 were investigated at room temperature in the solid state.     

Syntheses,Structures, and Photophysical Properties of Two Coordination Polymers Based on 2,3‐Dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic Acid

Two complexes based on the ligand 1,4‐dihydro‐2,3‐quinoxalinedione, namely [Mn(H₂L)₂(H₂O)₂]_n ( 1 ) and {[Zn₂(H₂L)₂(tz)₂] · 5H₂O}_n ( 2 ) (H₃L = 2,3‐dioxo‐1,2,3,4‐tetrahydroquinoxaline‐6‐carboxylic acid, Htz = 1,2,4‐triazole) were hydrothermally synthesized and characterized by elemental analyses, IR spectroscopy, as well as single‐crystal and powder X‐ray diffraction. Complex 1 exhibited a 1D comb‐like chain formed by H₂L^– anions linking Mn^II ions, whereas complex 2 was a 2D layer‐like structure with square‐shaped windows and outstretched arms built by combination of H₂L^– and tz^– ligands with Zn^II ions. The adjacent chains or layers connected with each other by intermolecular hydrogen bonding and π–π stacking to further extend to a 3D supermolecular framework. In addition, the thermal stabilities, luminescence properties, and optical energy gap of 1 and 2 were investigated in detail.     

Construction of Four Coordination Polymers based on 2‐[4‐(Pyridine‐4‐yl)phenyl]‐1H‐imidazole‐4,5‐dicarboxylic Acid

The imidazole‐based dicarboxylate ligand 2‐(4‐(pyridin‐4‐yl)phenyl)‐1H‐imidazole‐4,5‐dicarboxylic acid (H₃PyPhIDC), was synthesized and its coordination chemistry was studied. Solvothermal reactions of Ca^II, Mn^II, Co^II, and Ni^II ions with H₃PyPhIDC produced four coordination polymers, [Ca(μ₃‐HPyPhIDC)(H₂O)₂]_n ( 1 ), {[M₃(μ₂‐H₂PyPhIDC)₂(μ₃‐HPyPhIDC)₂₆(H₂O)₂] · 6H₂O}_n [M = Mn ( 2 ), Co ( 3 )], and {[Ni(μ₃‐HPyPhIDC)(H₂O)] · H₂O}_n ( 4 ). Compounds 1 – 4 were analyzed by IR spectroscopy, elemental analyses, and single‐crystal and powder X‐ray diffraction. Compound 1 displays a one‐dimensional (1D) infinite chain. Compounds 2 and 3 are of similar structure, showing 2D network structures with a (4,4) topology based on trinuclear clusters. Compound 4 has another type of 2D network structure with a 3‐connected (4.8²) topology. The results revealed that the structural diversity is attributed to the coordination numbers and geometries of metal ions as well as the coordination modes and conformations of H₃PyPhIDC. Moreover, the thermogravimetric analyses of all the compounds as well as luminescence properties of the H₃PyPhIDC ligand and compound 1 were also studied.     

Cyano‐Bridged ‘Oximato’ Complexes: Synthesis,Structure, and Catalase‐Like Activities

The reaction of the ‘oximato’‐ligand precursor A (Fig. 1) and metal salts with KCN gave two mononuclear complexes [ML(CN)(H₂O)_n](ClO₄) ( 1 and 2 ; L={N‐(hydroxy‐κO)‐α‐oxo‐N′‐[(pyridin‐2‐yl‐κN)methyl[1,1′‐biphenyl]‐4‐ethanimidamidato‐κN′}; M=Co^II ( 1 ), Cu^II ( 2 ); n=2 for Co^II, n=0 for Cu^II; Figs. 2 and 3). The new cyano‐bridged pentanuclear ‘oximato’ complexes [{ML(H₂O)_n(NC)}₄M¹(H₂O)_x](ClO₄)₂ ( 3 – 6 ) and trinuclear complexes [{ML(H₂O)_n(NC)}₂M¹L](ClO₄) ( 7 – 10 ) ([M¹=Mn^II, Cu^II; x=2 for Mn^II, x=0 for Cu^II] were synthesized from mononuclear complexes and characterized by elemental analyses, magnetic susceptibility, molar conductance, and IR and thermal analysis. The four [ML(CN)(H₂O)_n]⁺ moieties are connected by a metal(II) ion in the pentanuclear complexe 3 – 6 , each one involving four cyano bridging ligands (Fig. 4). The central metal ion displays a square‐planar or octahedral geometry, with the cyano bridging ligands forming the equatorial plane. The axial positions are occupied by two aqua ligands in the case of the central Mn‐atom. The two [ML(CN)(H₂O)_n]⁺ moieties and an ‘oximato’ ligand are connected by a metal(II) ion in the trinuclear complexes 7 – 10 , each one involving two cyano bridging ligands (Fig. 5). The central metal ions display a distorted square‐pyramidal geometry, with two cyano bridging ligands and the donor atoms of the tridentate ‘oximato’ ligand. Moreover catalytic activities of the complexes for the disproportionation of hydrogen peroxide (H₂O₂) were also investigated in the presence of 1H‐imidazole. The synthesized homopolynuclear Cu^II complexes 6 and 10 displayed eficiency in disproportion reactions of H₂O₂ producing H₂O and dioxygen thus showing catalase‐like activity.     

Poly[[diaquamanganese(II)]‐μ3‐4‐oxido‐2‐oxo‐1,2‐dihydropyrimidine‐5‐carboxylato‐κ4O4,O5:O2:O2]

In the title compound, [Mn(C₅H₂N₂O₄)(H₂O)₂]_n, the Mn^II ion has a distorted octahedral geometry and the 4‐oxido‐2‐oxo‐1,2‐dihydropyrimidine‐5‐carboxylate (Hiso²⁻) anion acts as a μ₃:η⁴‐bridging ligand. Two oxo O atoms from different Hiso²⁻ ligands bridge two Mn^II ions, forming centrosymmetric dinuclear building blocks. Each dinuclear building block interacts with another four by the coordination of the oxide groups and carboxylate O atoms, producing a two‐dimensional framework in the ab plane. Hydrogen bonds further extend the two‐dimensional sheets into a three‐dimensional supramolecular framework.     

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 managnese(II) coordination polymer constructed by 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylate)

In recent years, N‐heterocyclic carboxylate ligands have attracted much interest in the preparation of new coordination polymers since they contain N‐atom donors, as well as O‐atom donors, and have a rich variety of coordination modes which can lead to polymers with intriguing structures and interesting properties. A new two‐dimensional coordination polymer, namely poly[[μ₃‐2,2′‐(1,2‐phenylene)bis(4‐carboxy‐1H‐imidazole‐5‐carboxylato)‐κ⁶O⁴,N³,N^3′,O^4′:O⁵:O^5′]manganese(II)], [Mn(C₁₆H₈N₄O₈)]_n or [Mn(H₄Phbidc)]_n, has been synthesized by the reaction of Mn(OAc)₂·4H₂O (OAc is acetate) with 2,2′‐(1,2‐phenylene)bis(1H‐imidazole‐4,5‐dicarboxylic acid) (H₆Phbidc) under solvothermal conditions. In the polymer, each Mn^II ion is six‐coordinated by two N atoms from one H₄Phbidc²⁻ ligand and by four O atoms from three H₄Phbidc²⁻ ligands, forming a significantly distorted octahedral MnN₂O₄ coordination geometry. The Mn^II ions are linked by hexadentate H₄Phbidc²⁻ ligands, leading to a two‐dimensional structure parallel to the ac plane. In the crystal, adjacent layers are further connected by N—H…O hydrogen bonds, forming a three‐dimensional structure in the solid state.     

Poly[diaqua­(μ‐4,4′‐bipyridine)tetra­kis­(μ‐ferro­cenecarboxyl­ato)bis­(ferro­cenecarboxyl­ato)­tri­man­ganese(II)]

The title compound, [Mn₃Fe₆(C₅H₅)₆(C₆H₄O₂)₆(C₁₀H₈N₂)(H₂O)₂]_n, consists of two crystallographically unique Mn^II centers. One is situated on an inversion center and is octa­hedrally coordinated by two N atoms from two bridging 4,4′‐bipyridine (4,4′‐bipy) ligands and four O atoms, two from different bridging ferrocenecarboxyl­ate (μ₂‐FcCOO⁻; Fc is ferrocene) units and two from aqua ligands. The two halves of each 4,4′‐bipy ligand are related by a center of symmetry. The second Mn^II center is in a strongly distorted tetra­gonal–pyramidal geometry, coordinated by five O atoms, three from three μ₂‐FcCOO⁻ units and two from a fourth, chelating, η²‐FcCOO⁻ unit. The FcCOO⁻ units function as bridging ligands to adjacent Mn^II centers, leading to the formation of linear ⋯Mn1Mn2Mn2Mn1⋯ chains. Adjacent chains are further bridged by 4,4′‐bipy ligands, resulting in a two‐dimensional layered polymer.     

Synthesis,Structure, and Magnetic Properties of a Mn4 Cluster derived from Benzimidazole‐Alcohol Ligands

The synthesis, crystal structure, and magnetic properties of a [Mn^III₃Mn^II(μ₃‐O)(mbp)₃(OAc)₃] · 4H₂O ( 1 ) [H₂mbp = 2‐(1H‐benzimidazol‐2‐yl)‐2‐ methylpropane‐1,3‐diol] cluster are reported herein. Mn ions in compound 1 have a tetrahedron topology. Solid‐state direct current and alternating current magnetic susceptibility measurements on compound 1 reveal a ground state with S_T = 7/2 as well as the probable single‐molecule magnetic behavior.     

Synthesis,Crystal Structure and Magnetic Behaviour of Two 1‐D Chain Manganese‐Nitroxide Complexes Bridged by Isophthalate Anions

Two one‐dimensional (1‐D) chain manganese‐nitroxide complexes {[Mn(NIT4Py)₂(ip)(H₂O)₂]·4H₂O}_n ( 1 ) and [Mn(IM4Py)₂(ip)(H₂O)₂]_n ( 2 ) (NIT4Py = 2‐(4′‐pyridinyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl‐3‐oxide, IM4Py = 2‐(4′‐pyridinyl)‐4,4,5,5‐tetramethylimidazoline‐1‐oxyl and ip = isophthalate anion) have been synthesized and characterized by elemental analyses, IR spectrum and electronic absorption spectra. Complex 1 was structurally characterized and it crystallizes in neutral 1‐D chains where Mn^II nitroxide units [Mn(NIT4Py)₂(H₂O)₂] are linked by isophthalate anions. The magnetic measurements show that complex 1 exhibits antiferromagnetic couplings, while complex 2 exhibits ferromagnetic interactions between the Mn^II ion and the nitroxide radicals.     

{[Mn2(μ3‐Tda)2(μ‐H2O)(H2O)2(bipy)]·DMF}n – a 2D Manganese(II) Coordination Polymer involving Six‐membered Binuclear Metallacycle Nodes

The single crystal X‐ray analysis of a novel thiophene‐2,5‐dicarboxylic acid (H₂Tda) Manganese(II) coordination polymer, {Mn₂(μ₃‐Tda)₂(μ‐H₂O)(H₂O)₂(bipy)]·DMF}_n, shows two different types of Mn²⁺‐ions with environment of Mn1O₆ and Mn2O₄N₂, and the complex is a two‐dimensional polymer as a result of bridging (Tda)^2? ligands and by connecting the carboxylate‐ and water‐bridged {Mn₂(μ‐Tda)₂(μ‐H₂O)} nodes.     

Poly[[bis(pyridin‐3‐ol)manganese(II)]‐di‐μ‐pyridin‐3‐olato]

In the title complex, [Mn(C₅H₄NO)₂(C₅H₅NO)₂]_n or [Mn(μ‐3‐PyO)₂(3‐PyOH)₂]_n (3‐PyO⁻ is the pyridin‐3‐olate anion and 3‐PyOH is pyridin‐3‐ol), the Mn^II atom lies on an inversion centre and has octahedral geometry, defined by two N atoms and two deprotonated exocyclic O atoms of symmetry‐related pyridin‐3‐olate ligands [Mn—N = 2.3559 (14) Å and Mn—O = 2.1703 (11) Å], as well as two N atoms of terminal 3‐PyOH ligands [Mn—N = 2.3482 (13) Å]. The Mn^II atoms are bridged by the deprotonated pyridin‐3‐olate anion into a layer structure, generating sheets in the (01) plane. These sheets are linked by O—H⋯O hydrogen bonds. There are also π–π and C—H⋯π interactions in the crystal structure.     

Influence of the Metal Ions on the Allylic Rearrangement Reaction of 3,4,5,6‐Tetrahydrophthalic Anhydride

To further investigate the influence of metal ions on the allylic rearrangement of 3,4,5,6‐tetrahydrophthalic anhydride during the hydrothermal reaction, metal ions such as manganese(II), zinc(II) and cadmium(II) have been employed in the synthesis, which leads to the formation of three new lamellar coordination polymers, [Mn^II₅(µ₃‐OH)₃(1‐chec)(1,2‐chedc)(2,3‐chedc)₂(H₂O)] ( 3Mn) , [Zn^II₅(µ₃‐OH)₃(1‐chec)(1,2‐chedc)(2,3‐chedc)₂(H₂O)] ( 4Zn ), and [Cd^II₃(µ₃‐OH)₂(1,2‐chedc)₂] ( 5Cd) (1‐chec=cyclohexene‐1‐carboxylate, 1,2‐chedc=cyclohexene‐1,2‐dicarboxylate, 2,3‐chedc=cyclohexene‐1,2‐dicarboxylate). Interestingly, the allylic rearrangement reaction is metal‐dependent, which occurs only in 3Mn and 4Zn , resulting in the formation of one chiral carbon atom of the corresponding dicarboxylate ligands in both compounds. In addition, the magnetic property of compound 3Mn was studied, which revealed strong antiferromagnetic interactions between the metal centers.     

Poly­[trans‐di­aqua­manganese(II)‐μ‐(3‐pyridine­carboxyl­ato‐N:O)‐μ‐(3‐pyri­dinecarboxyl­ato‐O:N)]

The title complex, [Mn^II(nic)₂(H₂O)₂]_n [nic is 3‐pyridine­carboxyl­ate (also called nicotinate), C₆H₄NO₂^?], has a two‐dimensional layer structure with the unique Mn atom on an inversion centre. In each layer, all nicotinate ligands are coordinated to Mn atoms in a bridging/bidentate mode, thus linking the {Mn^II(nic)₂(H₂O)₂} monomeric units together to form a dative‐bond‐based layered polymer. The intra‐layer hydrogen bonds involving all water mol­ecules and the carboxyl­ate groups may play an auxiliary part in stabilizing the layer. The layers are arranged in an ordered manner along the a axis through van der Waals forces so as to complete the solid‐state structure of the crystal.     

Poly[diaqua[μ‐1,4‐bis(imidazol‐1‐ylmethyl)benzene‐κ2N3:N3′](μ‐trans‐cyclohexane‐1,4‐carboxylato‐κ2O1:O4)manganese(II)]: a three‐dimensional hydrogen‐bonding α‐polonium net

In the title coordination compound, [Mn(C₈H₁₀O₄)(C₁₄H₁₄N₄)(H₂O)₂]_n, each Mn^II centre occupies an inversion centre. The 1,4‐bis(imidazol‐1‐ylmethyl)benzene (1,4‐bix) ligand and the trans‐cyclohexane‐1,4‐dicarboxylate dianion (chdc) both function in bridging modes, linking adjacent Mn^II centres into a two‐dimensional four‐connected (4,4) network. These two‐dimensional layers are stacked in a parallel mode. Hydrogen bonds between water molecules and carboxylate O atoms link neighbouring (4,4) networks, yielding a three‐dimensional α‐polonium net.     

Tetranuclear Manganese Complex Incorporating 2‐Pyridyloximate Ligand: Synthesis,Crystal Structure and Magnetic Property

A tetranuclear manganese complex of the composition {Mn₄[(Py)C(Ph)NO]₄(CH₃CH₂OH)₃(CH₃CH₂O)Cl₃}·2H₂O ( 1 ) was synthesized by solvothermal reaction, and characterized by X‐ray single crystal diffraction, IR spectroscopy, and elemental analysis. X‐ray analysis revealed that complex 1 contains a [Mn₄(NO)₄]⁴⁺ core with three Mn^II atoms displaying distorted octahedral arrangements and one Mn^II ion exhibiting a trigonal bipyramidal arrangement. Low‐temperature magnetic susceptibility measurement for the solid sample of 1 revealed antiferromagnetic Mn^II ··· Mn^II interactions.     

A three‐dimensional manganese(II) metal–organic framework based on 5‐methoxybenzene‐1,3‐dicarboxylic acid and exhibiting a pts net

The solvothermal reaction of MnCl₂·H₂O and 5‐methoxybenzene‐1,3‐dicarboxylic acid (MeO‐m‐H₂BDC) led to a three‐dimensional Mn^II metal–organic framework, namely poly[(dimethylformamide‐κO)(μ₄‐5‐methoxybenzene‐1,3‐dicarboxylato‐κ⁴O¹:O^1′:O³,O^3′:O³)manganese(II)], [Mn(C₉H₆O₅)(C₃H₇NO)]_n or [Mn(MeO‐m‐BDC)(DMF)]_n (DMF is dimethylformamide). The Mn^II atom is six‐coordinated and exhibits a distorted octahedral geometry formed by five carboxylate O atoms from four different MeO‐m‐BDC²⁻ anionic ligands and by one DMF O atom. The three‐dimensional framework of (I) formed by the bridging MeO‐m‐BDC²⁻ ligands and the Mn^II atoms exhibits a pts topological network when MeO‐m‐BDC²⁻ and Mn^II are viewed as four‐connected nodes.