Synthesis, structures and magnetic properties of two 3D 3,4-pyridinedicarboxylate bridged manganese(II) coordination polymers incorporating 1D helical Mn(carboxylate)2 chain or Mn3(OH)2 chain

The hydrothermal reactions of MnCl₂·4H₂O, 3,4-pyridinedicarboxylic acid (3,4-pydaH₂) and triethylamine in aqueous medium yield two 3D metal-organic hybrid materials, [Mn(3,4-pyda)] (1) and [Mn₃(OH)₂(3,4-pyda)₂(H₂O)₂] (2), respectively. In both complexes, each 3,4-pyda acts as a pentadentate ligand to connect five Mn(II) atoms via the pyridyl group and the two μ₂-carboxylate groups (one in syn,anti-mode and one in syn-syn mode for 1 and both in syn,anti-mode for 2). Complex 1 possesses an interesting 3D coordination polymeric structure incorporating 1 D helical Mn(μ₂-carboxylate)₂ chain units, in which each Mn(II) atom is coordinated in less common square pyramidal geometry to four carboxylato oxygen atoms and one pyridyl nitrogen atom. Each 3,4-pyda links three helical Mn(μ₂-carboxylate)₂ chains and each Mn(μ₂-carboxylate)₂ chain is linked by other eight helical Mn(μ₂-carboxylate)₂ chains via sharing 3,4-pyda bridges. Complex 2 is a 3D coordination network consisting of 1D Mn₃(OH)₂ chains and 3,4-pyda bridges. The repeating trimeric structural unit in the manganese(II) hydroxide chain consists of two edge-sharing symmetry-related manganese octahedra linked via μ₃-OH to a vertex of Mn₂ octahedron. Each 3,4-pyda links three Mn₃(OH)₂ chains and each Mn₃(OH)₂ chain is linked by other six Mn₃(OH)₂ chains via 3,4-pyda bridges, resulting in a 3D coordination solid. Magnetic measurements reveal that a weak antiferromagnetic interaction between the Mn^II ions occurs in complex 1 and a 3D magnetic ordering at about 7.0 K in complex 2.     

A new 2D Mn(II) coordination polymer constructed from carboxylate and N-donor coligand: Synthesis,structure, and magnetism

A new complexes, namely, {[Mn₂(L)₂(Bipy)₂] · H₂O} _n (I) (H₂L = diphenic acid, Bipy = 4,4′-bipyridine) has been synthesized and structurally characterized by single-crystal diffraction analysis. In I, the two syn, anti-carboxylate groups in L bridge Mn(II) forming a one-dimensional chain, which is further connected by Bipy into 2D double layer. Magnetic study reveals the overall antiferromagnetic interaction between neighboring Mn²⁺ ions in compound I.     

Synthesis,characterization and crystal structure of a new linear trinuclear manganese(II) complex, [Mn3(PhCH=CHCO2)6(BPY)2] · H2O (BPY=2,2-bipyridine)

A new trinuclear manganese(II) complex, [Mn₃(PhCH=CHCO₂)₆(bpy)₂]?·?H₂O (1) (bpy?=?2,2-bipyridine), was synthesized by the reaction of Mn(OH)₂ with cinnamate in H₂O/methanolic solution and its solid state structure was determined by single crystal X-ray diffraction. Structural analyses suggest that 1 consists of a linear arrangement of three Mn(II) centers, bridged by six cinnamate carboxylate groups. Four of these carboxylates are syn–syn bidentate, and two are monodentate bridging plus bidentate chelating. Mn(2) on a crystallographic inversion center has a slightly disorted octahedral geometry; the terminal six-coordinate Mn(1) atoms are significantly distorted octahedra. Weak intermolecular interactions such as C–H?···?O hydrogen-bonding and π–π stacking are responsible for supramolecular assembly of the molecules. Compound 1 was characterized by infrared spectrum, thermogravimetric and X-ray powder diffraction analyses.     

Synthesis and Crystal Structure of Manganese(II) Bipyridine Carboxylato Complexes: [(bipy)2MnII(μ‐C2H5CO2)2MnII(bipy)2](ClO4)2 and [MnII(ClCH2CO2)(H2O)(bipy)2]ClO4 · H2O (bipy = 2,2′‐bipyridine)

Two manganese(II) bipyridine carboxylate complexes, [(bipy)₂Mn^II(μ‐C₂H₅CO₂)₂Mn^II(bipy)₂}₂](ClO₄)₂ ( 1 ), and [Mn^II(ClCH₂CO₂)(H₂O)(bipy)₂]ClO₄ · H₂O ( 2 ) were prepared. 1 crystallizes in the triclinic space group P 1 with a = 8.604(3), b = 12.062(3), c = 13.471(3) Å, α = 112.47(2), β = 93.86(2), γ = 92.87(3)°, V = 1211.1(6) ų and Z = 1. In the dimeric, cationic complex with a crystallographic center of symmetry two 2,2′‐bipyridine molecules chelate each manganese atom. These two metal fragments are then bridged by two propionato groups in a syn‐anti conformation. The Mn…Mn distance is 4.653 Å. 2 crystallizes in the monoclinic space group P2₁/c with a = 9.042(1), b = 13.891(1), c = 21.022(3) Å, β = 102.00(1)°, V = 2569.3(5) ų and Z = 4. 2  is a monomeric cationic complex in which two bipyridine ligands chelate the manganese atom in a cis fashion. A chloroacetato and an aqua ligand complete the six‐coordination. Only in 2 is the intermolecular packing controlled by weak π‐stacking besides C–H…π contacts between the bipyridine ligands.     

Two Mn4Mn8 clusters from the use of tripodal ligands showing single-molecule magnet behavior

The reaction of manganese(II) acetylacetonate (Mn(acac)₂), 1,1,1-tris(hydroxymethyl)ethane (H₃thme), tris(hydroxymethyl)aminomethane (H₃thma), and (CH₃)₃CCO₂H, adamantane-1-carboxylic acid (Hada) in solvothermal method leads to two mixed-valence Mn^III₄Mn^II₈ clusters, [Mn(III)₄Mn(II)₈(μ₅-O)₂(μ₃-MeO)₂(thme)₄(Me₃CCO₂)₁₀(H₂O)₂]·2H₂O (1) and [Mn(III)₄Mn(II)₈(μ₅-O)₂(μ₃-MeO)₂(thma)₄(ada)₁₀(H₂O)₂]·4H₂O (2). The Mn^III₄Mn^II₈ cores of the complexes can be described as a central rhomboid [Mn₄O₆] layer sandwiched by two [Mn₄O₇] layers, or capped edge-sharing bioctahedra. The co-parallel alignment of four JT axes of the Mn^III ions enhances the magnetic anisotropy of the Mn₁₂ molecules. For the population of low-lying excited states, the attempts to fit the direct current (dc) data of two complexes were failed, while rough spin ground state S = 4 for 1 and S = 2 or 3 for 2 were obtained from alternating current (AC) magnetization studies. The two compounds show clearly nonzero and frequency-dependent out-of-phase (χ_M′′) ac signal below 3 K, indicating a slow relaxation of the magnetization, confirming 1 and 2 to be SMMs, though out-of-phase AC peak above 1.8 K was not observed. The substitution of tripodal ligands and carboxylate ligands leads to different coordinate modes of the pivalate ligands in the Mn₁₂ clusters and varies the packing modes of Mn₁₂ molecules in the crystal.     

Synthesis and Characterization of [Mn3(ppi)2(μ‐OAc)4(H2O)2] · 2MeOH — Unusual Structural Properties of a Trinuclear Oxygen‐Rich Manganese Complex

The trinuclear manganese(II) complex [Mn₃(ppi)₂(μ‐OAc)₄(H₂O)₂]·2MeOH ( 1 ) (Hppi = 2‐pyridylmethyl‐2‐hydroxyphenylimine) is prepared by dissolving two equivalents of Hppi (from the Schiff Base reaction of aminophenol and pyridine‐2‐carboxaldehyde) in acetonitrile and three equivalents of Mn(OAc)₂·4H₂O in methanol and combining both solutions. The resulting red precipitate was recrystallized to yield red crystals suitable for single crystal X‐ray diffraction. Compound 1 crystallizes in the triclinic space group P1¯ (no. 2), with a = 9.691(2), b = 10.683(2), c = 11.541(2)Å, α = 63.19(3)°, β = 67.47(3)°, γ = 69.11(3)°, V = 960.2(3)ų, and Z = 1. The binding mode of carboxylate in 1 represents a model for a transition state between symmetric syn, syn, anti‐μ₂‐carboxolato‐O‐ and syn, anti‐μ₂‐carboxylato‐O, O′‐coordination. Therefore a rare binding mode for the phenomenon of the carboxylate shift is realized. Furthermore the complex is stabilized by a distinctive hydrogen bonding pathway.     

Three new dinuclear manganese(II) complexes with bis(μ-phosphinato)-bridges

A new series of dinuclear phosphinato-bridged manganese(II) complexes [Mn(μ-bmp)(bpy)(NO₃)]₂ (1), [Mn(μ-bmp)(phen)(NO₃)]₂·4CH₂Cl₂ (2) and [Mn₂(μ-bmp)₂(5-dmbpy)₂(NO₃)]₂ (3) where Hbmp is bis(4-methoxyphenyl)phosphinic acid, bpy = 2,2′-bipyridyl, phen = 1,10-phenanthroline and 5-dmbpy = 5,5′-dimethyl-2,2′-dipyridyl, have been synthesized and structurally characterized by X-ray crystallography. In this series, the structures consist in bis(4-methoxyphenyl)phosphinato anions (bmp) bridging the two Mn(II) centers in a syn-syn coordination mode. The coordination geometry around the Mn(II) ions in 1-3 is six-coordinate with distorted octahedral environment. The magnetic behavior of these complexes is reported. The complexes show weak antiferromagnetic coupling with |J| in the range 0.1-0.6 cm⁻¹. The magnetic properties are discussed in relation to the structural data.     

Structural diversity of homochiral cadmium-camphorates with 2,2′-bipyridine

Homochiral framework materials are of current interest due to their potential applications in asymmetric catalysis and enantioselective separation. Four new Cd(II) camphorates (1–4) with 2,2′-bipyridine ligand (= 2,2′-bipy) are successfully synthesized and show distinct structural features. Such rich Cd-cam-2,2′-bipy system is composed of four compounds, [Cd(d-cam)(2,2′-bipy)(DMF)]_n (1), [Cd(d-cam)(2,2′-bipy)(H₂O)]_n (2), [Cd₂(d-cam)₂(2,2′-bipy)₂]_n (3) and [Cd₂Cu₂(d-cam)₄(2,2′-bipy)₂]_n·4nH₂O (4), which are obtained under different conditions. Both compounds 1 and 2 show infinite homochiral Cd-camphorate chain, while compounds 3 and 4 exhibit homochiral layered structures based on different dinuclear units. The results demonstrate the rich coordination chemistry of the enantiopure d-camphorate ligand and the structural diversity of metal-camphorate compounds.     

Mixed-valent tetranuclear manganese complexes with pentadentate Schiff-base ligand having a Y-shaped core

Reaction of pentadentate Schiff-base ligands, 1,3-bis(3-methoxysalicylideneamino)-2-propanol (H₃msap) with manganese(II) salts afforded tetranuclear mixed-valent manganese complexes, [Mn₄(msap)₂(CH₃CO₂)₃(CH₃O)(H₂O)]·H₂O (1) and [Mn₄(msap)₂(C₆H₅CO₂)₃(CH₃O)] (2), which were characterized by elemental analysis, infrared and diffused reflectance spectra and temperature dependence of magnetic susceptibilities (4.5–300 K). Single-crystal X-ray crystallography of these complexes showed that four manganese atoms are chelated by two Schiff-base ligands and further coordinated by syn–syn bridging, syn–anti bridging, and monodentate or bidentate-carboxylato groups, forming a Y-shaped cluster made up of two Mn^II and two Mn^III atoms. Diffused reflectance spectra are featureless, showing broad bands around at near-UV and visible regions. Magnetic moments decrease with lowering of temperature, showing an antiferromagnetic behavior of these complexes.     

Mehrfachbindungen zwischen Hauptgruppenelementen und Übergangsmetallen: XLVVI. Nachweis der Elektrophilie eines trigonal-planar koordinierten Telluratoms

The central tellurium atom coordinated to three manganese atoms in the compound (υ₃-Te)[(η⁵-C₅H₅)Mn(CO)₂]₃ (1) exhibits electrophilic reactivity, thus undergoing methylation with methyllithium to yield the anion [(μ₃-TeCH₃){;(η⁵-C₅H₅)Mn(CO)₂};₃]⁻, whose structure was determined crystallographically. While the precursor compound 1 contains a planar Mn₃Te core structure (d(Mn-Te) 248.7 pm, av.), carbanion addition effects pyramidalization of this fragment (d(Mn-Te) 257.7 pm, av.), with the tellurium atom appearing at a distance of 56 pm above the plane defined by the three manganese atoms.     

Two new supramolecular assemblies based on Keggin-type polyoxometalates through AgO and ππ stacking interactions

Two new supramolecular assemblies based on Keggin-type polyoxometalates, [Ag₃(4,4′-bipy)₂(2,2′-bipy)₂][Ag(2,2′-bipy)₂][{Ag(2,2′-bipy)}HSiW₁₁VO₄₀] (1) and [Ag₃(4,4′-bipy)₂(2,2′-bipy)₂][Ag(2,2′-bipy)₂][{Ag(2,2′-bipy)}PW₁₁VO₄₀] (2) (4,4′-bipy = 4,4′-bipyridine, 2,2′-bipy = 2,2′-bipyridine), have been synthesized under the hydrothermal conditions and structurally characterized by IR, XPS, TG and single-crystal X-ray diffraction. Compound 1 has a 2D layer network structure via weak Ag^...O interactions. Compound 2 is isostructural with compound 1. In addition, the fluorescence of compound 1 is reported.     

Magnetic properties of two double‐layer structures built from hydroxy­naphthoic acids and manganese

Double‐layer structures consisting of alternating polar and non‐polar layers have been prepared using Mn²⁺ ions and o‐hydroxy­naphthoic acids. The polar layers contain the Mn²⁺ ions, carboxylate groups, hydr­oxy groups and water mol­ecules. The non‐polar layers are built up from the naphthalene moieties. In catena‐poly[[diaqua­manganese(II)]bis­(μ‐3‐hy­droxy‐2‐naphthoato‐κ²O:O′)] (also called manganese 3‐hy­droxy‐2‐naphthoate dihydrate), [Mn(C₁₁H₇O₃)₂(H₂O)₂]_n, (I), the Mn²⁺ ions are connected by carboxylate groups to form two‐dimensional networks. This compound shows distinct antiferromagnetic inter­actions and long‐range ordering at low temperature. In contrast, tetra­aqua­bis(1‐hydr­oxy‐2‐naph­thoato‐κO)manganese(II), [Mn(C₁₁H₇O₃)₂(H₂O)₄], (II), which lacks a close linkage between the Mn²⁺ ions, reveals purely paramagnetic behaviour. In (II), the Mn²⁺ ion lies on an inversion centre.     

Synthesis, crystal structure and magnetic properties of three polynuclear manganese compounds bearing ferrocenecarboxylato ligands

The reactions of sodium ferrocenecarboxylate (FcCO₂Na) and Mn(ClO₄)₂ · 6H₂O in methanol in the presence of ancillary ligands of 1,10-phenanthroline (phen) or 2,2′-bipyridine (2,2′-bpy) produce three discrete polynuclear complexes bearing ferrocenecarboxylato ligands: [Mn₂(FcCO₂)₃(phen)₂](ClO₄) · 2CH₂Cl₂ (1), [Mn₃(FcCO₂)₆(2,2′-bpy)₂] · 2H₂O (2) and [Mn₄O₂(FcCO₂)₇(2,2′-bpy)₂]ClO₄ · 2CH₂Cl₂ · 6H₂O (3). It is shown that their composition and skeletons are tuned by the ancillary ligands and the ratios of starting materials. In dimanganese complex 1, both Mn(II) ions are pentacoordinated in a distorted trigonal bipyramidal geometry and bridged by three ferrocenecarboxylato ligands in a distorted syn-syn bridging mode, which is rare in triply carboxylato-bridged dimanganese complexes. Compound 2 presents a linear trinuclear [Mn₃(μ₂-η¹:η¹-O₂CFc)₄(μ₂-η¹:η²-O₂CFc)₂] core, in which six ferrocencarboxylato ligands show two different bridging modes. The cationic Mn₄O₂ core of 3 has a butterfly structure, in which two Mn(III) ions at “body” sites are bridged by an additional ferrocenecarboxylato ligand and they are further connected to the Mn(III) ions at “wing-tip” sites by ferrocenecarboxylato ligands. Magnetic susceptibilities of 1 and 2 were measured. Both of them mediate a weak antiferromagnetic coupling between the Mn(II) ions bridged by ferrocenecarboxylato ligands.     

2-Benzothiazolylthioacetic acid and 4,4′-bipyridine as ligands in designing low-dimensional coordination polymers: Synthesis, architectures and magnetic properties

The combined use of 4,4′-bipyridine (4,4′-bipy) and 2-benzothiazolylthioacetic acid (HBTTAA) as ligands with Mn(II), Cd(II), Co(II) and Cu(II) ions afforded six polymeric complexes, namely {[Mn₃(BTTAA)₄(4,4′-bipy)₄](ClO₄)₂ · 2H₂O}_n (1), [Mn(BTTAA)₂(4,4′-bipy)₂]_n (2), [Cd(BTTAA)₂(4,4′-bipy)₂]_n (3), [Cd(BTTAA)(4,4′-bipy)(NO₃)(H₂O)]_n (4), [Co(BTTAA)₂(4,4′-bipy)(H₂O)₂]_n (5) and [Cu(BTTAA)₂(4,4′-bipy)]_n (6). All these complexes have been characterized by a combination of analytical, spectroscopic and crystallographic methods. Complex 1 is a novel 2D network formed by two different 4⁴ grid networks, whereas isomorphous complexes 2 and 3 exhibit a 2Dl coordination architecture formed by the same 4⁴ grid network. In 4–6, extended 1D chains are formed, with the 4,4′-bipy molecules acting as rigid rod-like links between adjacent metal centers. The carboxylato groups of BTTAA in these complexes exhibit four different coordination modes, namely monodentate, chelating, bridging and bridging-chelating modes. The magnetic properties of 1, 2, 5 and 6 were investigated in the temperature range 2.0–300.0 K. Variable temperature magnetic susceptibility measurements show weak antiferromagnetic interactions in these complexes.     

Synthesis and characterization of a bis-μ,η-carboxylate-bridged dinuclear manganese(II) complex containing a tetradentate tripodal ligand, N-(benzimidazol-2-ylmethyl)iminodiacetic acid

The dinuclear Mn(II) complex, [Mn₂(Hbida)₂(H₂O)₂], was prepared using a tetradentate tripodal ligand, N-(benzimidazol-2-ylmethyl)iminodiacetic acid (H₃bida) which has two carboxylate and one benzimidazole groups. The manganese ions are doubly bridged using μ,η¹-bridging monodentate carboxylate oxygen atoms. The Mn–Mn bond distance of 3.446 Å in the complex is comparable to that observed in the active site of the native manganese arginase enzyme (3.30 Å). The geometry of the complex with four carboxylates in two different types of binding modes, non-bridging monodentate and μ,η¹-type bridging monodentate, mimics the active site structure of manganese arginase. The magnetic properties of the complex show a coupling constant of J = −0.471(1) cm⁻¹, which is consistent with weakly coupled antiferromagnetic Mn^II (S = 5/2) centers. The cyclic voltammograms of the Mn(II) complex in DMF show irreversible oxidation occurring around 570 mV (versus Ag/AgCl).     

Characterization of pure phase Zn(II) oxide nanoparticles via thermal decomposition of two zinc(II) complexes of the 6,6′-dimethyl-2,2′-bipyridine ligand

Two zinc(II) complexes [Zn(6,6′-dimethyl-2,2′-bipy)Cl₂] _n (1) and [Zn(6,6′-dimethyl-2,2′-bipy)I₂] _n (2) are synthesized from the reaction of the 6,6′-dimethyl-2,2′-bipy ligand with ZnCl₂ and ZnI₂. Zinc(II) oxide nanoparticles are synthesized by the thermolysis of [Zn(6,6′-dimethyl-2,2′-bipy)Cl₂] _n (1) and [Zn(6,6′-dimethyl-2,2′-bipy)I₂] _n (2) at two different temperatures. The ZnO nanoparticles are characterized by X-ray diffraction and scanning electron microscopy (SEM). SEM images show the average size of the ZnO nanoparticles produced of 50 nm and 60 nm in compounds 1 and 2 respectively.     

Two new polyoxometalate-based organic-inorganic hybrids: synthesis,crystal structure and characterization

Two new organic-inorganic hybrids, (4,4′-bipy)[Cu^I(2,2′-bipy)₂]₂[W₆O₁₉] (2,2′-bipy = 2,2′-bipyrine, 4,4′-bipy = 4,4′-bipyrine) (1) and (C₆H₅NO₂)₄{Mn^III(H₂O)}[As^IIIW₉O₃₃]₂{W(OH)}- {W(H₂O)}?～18H₂O (2), have been synthesized and characterized by elemental analysis, IR, TG, UV–Vis, XRPD, XPS, electrochemical analysis and single-crystal X-ray diffraction. Single crystal X-ray diffraction analysis shows that 1 is a new Lindqvist-type polyoxoanion bisupported by copper(I) coordination cations and 2,2′-bipy ligands and exhibits a three-dimensional (3-D) supermolecular framework by aromatic π–π stacking interactions. Compound 2 is constructed from a manganese(III)-substituted sandwich-type polyoxoanion based on [α-AsW₉O₃₃]^9? units and dissociative, protonated pyridine-4-carboxylic acid molecules, which act as the charge compensation cations. The cyclic voltammogram of 2 shows an irreversible redox process for Mn³⁺ ions.     

Versatile Reactivity of MnII Complexes in Reactions with N-Donor Heterocycles: Metamorphosis of Labile Homometallic Pivalates vs. Assembling of Endurable Heterometallic Acetates

Reaction of 2,2′-bipyridine (2,2′-bipy) or 1,10-phenantroline (phen) with [Mn(Piv)₂(EtOH)]_n led to the formation of binuclear complexes [Mn₂(Piv)₄L₂] (L = 2,2′-bipy (1), phen (2); Piv⁻ is the anion of pivalic acid). Oxidation of 1 or 2 by air oxygen resulted in the formation of tetranuclear Mn^II/III complexes [Mn₄O₂(Piv)₆L₂] (L = 2,2′-bipy (3), phen (4)). The hexanuclear complex [Mn₆(OH)₂(Piv)₁₀(pym)₄] (5) was formed in the reaction of [Mn(Piv)₂(EtOH)]_n with pyrimidine (pym), while oxidation of 5 produced the coordination polymer [Mn₆O₂(Piv)₁₀(pym)₂]_n (6). Use of pyrazine (pz) instead of pyrimidine led to the 2D-coordination polymer [Mn₄(OH)(Piv)₇(µ₂-pz)₂]_n (7). Interaction of [Mn(Piv)₂(EtOH)]_n with FeCl₃ resulted in the formation of the hexanuclear complex [Mn^II₄Fe^III₂O₂(Piv)₁₀(MeCN)₂(HPiv)₂] (8). The reactions of [MnFe₂O(OAc)₆(H₂O)₃] with 4,4′-bipyridine (4,4′-bipy) or trans-1,2-(4-pyridyl)ethylene (bpe) led to the formation of 1D-polymers [MnFe₂O(OAc)₆L₂]_n·2nDMF, where L = 4,4′-bipy (9·2DMF), bpe (10·2DMF) and [MnFe₂O(OAc)₆(bpe)(DMF)]_n·3.5nDMF (11·3.5DMF). All complexes were characterized by single-crystal X-ray diffraction. Desolvation of 11·3.5DMF led to a collapse of the porous crystal lattice that was confirmed by PXRD and N₂ sorption measurements, while alcohol adsorption led to porous structure restoration. Weak antiferromagnetic exchange was found in the case of binuclear Mn^II complexes (J_Mn-Mn = −1.03 cm⁻¹ for 1 and 2). According to magnetic data analysis (J_Mn-Mn = −(2.69 ÷ 0.42) cm⁻¹) and DFT calculations (J_Mn-Mn = −(6.9 ÷ 0.9) cm⁻¹) weak antiferromagnetic coupling between Mn^II ions also occurred in the tetranuclear {Mn₄(OH)(Piv)₇} unit of the 2D polymer 7. In contrast, strong antiferromagnetic coupling was found in oxo-bridged trinuclear fragment {MnFe₂O(OAc)₆} in 11·3.5DMF (J_Fe-Fe = −57.8 cm⁻¹, J_Fe-Mn = −20.12 cm⁻¹).     

Two new hydrogen bond-supported supramolecular compounds assembly from tungsten-vanadium polyoxoanions and copper complex fragments

Two new supramolecular compounds based on tungsten-vanadium polyoxoanions formulated as [Cu(2,2′-bipy)₃]₂H₁₄[PW_2.2V_9.8O₄₀(VO)₂[Cu(2,2′-bipy)₂H₂O]₂][PW_2.2V_9.8O₄₀(VO)₂]·10H₂O (1) and [Cu₄(2,2′-bipy)₄(H₂O)₂(PO₄)₂]H_6.5[PW_8.4V_3.6O₄₀]·2H₂O (2) (2,2′-bipy=2,2′-bipyridine) have been synthesized hydrothermally and characterized by IR, TG, XPS and X-ray diffraction analyses. Crystal structure analyses reveal that compounds 1 and 2 exhibit novel 2D supramolecular layer structures constructed from tungsten-vanadium polyoxoanions and different types of secondary building units (SBUs), respectively, the different SBUs are formed by [Cu(2,2′-bipy)₂H₂O]²⁺ and [Cu(2,2′-bipy)₃]²⁺ cations in compound 1 and [Cu₄(2,2′-bipy)₄(H₂O)₂(PO₄)₂]²⁺ cations in 2, respectively. Study of magnetic properties indicated the presence of antiferromagnetic behaviors for both compound 1 and 2.     

Synthesis,crystal structures and properties of three glutarato and adipato bridged manganese(II) coordination polymers under ambient conditions

Three Mn(II) polymers Mn(H₂O)₄(C₅H₆O₄) 1, [Mn(H₂O)₂(C₅H₆O₄)]·H₂O 2 and Mn(H₂O)(C₆H₈O₄) 3 were synthesized (H₂(C₅H₆O₄) = glutaric acid, H₂(C₆H₈O₄) = adipic acid) under mild ambient conditions. The [Mn(H₂O)₂]²⁺ units in 2 are interlinked by the glutarate anions with a η⁴μ₃ bridging mode to form 2D (4·8²) topological networks, which are stacked via interlayer hydrogen bonds into a 3D (4³·6⁵·8²)(4⁷·6³) topological net. Compound 3 crystallizes in the acentric space group P2₁ and exhibits significant ferroelectricity (remnant polarization Pr = 0.371 nC cm⁻², coercive field Ec = 0.028 kV cm⁻¹, saturation of the spontaneous polarization Ps = 0.972 nC cm⁻²). The adjacent MnO₆ octahedrons in 3 are one atom-shared to generate the Mn₂O₁₁ bi-octahedron, leading into 1D metal oxide chains. The resulting chains are interconnected by the η⁵μ₅ adipate anions to form new 2D (4⁸·6²) networks, which are held together via strong interlayer hydrogen bonds into 3D α-Po topological supra-molecular architecture. The temperature-dependent magnetic susceptibility data of 1–3 shows overall anti-ferromagnetic interactions between the metal ions bridged by the carboxylate groups.