Mononuclear Anions Research Articles

Crystal-to-Crystal Transformation from K2[Co(C2O4)2(H2O)2]·4H2O to K2[Co(μ-C2O4)(C2O4)

Crystal-to-crystal transformation is a path to obtain crystals with different crystal structures and physical properties. K2[Co(C2O4)2(H2O)2]·4H2O (1) is obtained from K2C2O4·2H2O, CoCl2·6H2O in H2O with a yield of 60%. It is crystallized in the triclinic with space group P1 and cell parameters: a = 7.684(1) Å, b = 9.011(1) Å, c = 10.874(1) Å, α = 72.151(2)°, β = 70.278(2)°, γ = 80.430(2)°, V = 670.0(1) Å3, Z = 2 at 100 K. 1 is composed of K+, mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. Co2+ is coordinated by two bidentated oxalate anion and two H2O in an octahedron environment. There is a hydrogen bond between mononuclear anion [Co(C2O4)2(H2O)22−] and H2O. K2[Co(μ-C2O4)(C2O4)] (2) is obtained from 1 by dehydration. The cell parameters of 2 are a = 8.460(5) Å, b = 6.906 (4) Å, c = 14.657(8) Å, β = 93.11(1)°, V = 855.0(8) Å3 at 100 K, with space group in P2/c. It is composed of K+ and zigzag [Co(μ-C2O4)(C2O42−]n chain. Co2+ is coordinated by two bisbendentate oxalate and one bidentated oxalate anion in trigonal-prism. 1 is an antiferromagnetic molecular crystal. The antiferromagnetic ordering at 8.2 K is observed in 2.

Synthesis, Characterization and Thermal Analysis of an Organic-Inorganic Hybrid Salt Involving <i>Trans</i>-Diaquabis(oxalato-κ<sup>2</sup><i>O</i><sup>1</sup>,<i>O</i><sup>2</sup>)chromate(III) Complex Anion with Piperidinium as Counter Cation

A new organic-inorganic hybrid salt pipéridinium trans-diaquabis(oxalato)- chromate(III) tetrahydrate, (C5H10NH2)[Cr(C2O4)2(H2O)2]·4H2O (1), has been synthesized in water and characterized by FTIR and UV-Vis spectroscopies, elemental and thermal analyses and by single-crystal X-ray diffraction. 1 crystallizes in the orthorhombic non-centrosymmetric space group Cmc21 with the unit cell parameters a = 7.4329(3), b = 9.9356(5), c = 23.6756(11) Å, α = β = γ = 90°, V = 1748.45(14) Å3 and Z = 4. The structure of 1 consists of [Cr(C2O4)2(H2O)2]- mononuclear anions, piperidinium cations and uncoordinated water molecules. The CrIII ion in the complex [Cr(C2O4)2(H2O)2]- is coordinated in a slightly distorted octahedral environment by four O atoms from two chelating oxalate dianions in the equatorial plane, and two O atoms from trans-coordinated water molecules occupying the apical positions. In the crystal, N-H···O and O-H···O hydrogen bond interactions connect the components into a 3-D framework. The IR spectrum of 1 is consistent with the presence of the various molecular building constituents, namely oxalato and aqua ligands, piperidinium cations and solvent water molecules. The UV-Vis spectrum shows two absorption bands around 564 and 416 nm which are compatible with an anionic chromium(III) complex in an octahedral environment. Thermal analysis shows a three-step decomposition of 1, leading to formation of a metal oxide residue.

A Novel Chromium(III) Hybrid Salt, Triethylammonium <i>Trans</i>-Diaquabis(Oxalato-<i>κ</i><sup>2</sup>O<sup>1</sup>,O<sup>2</sup>) Chromate(III), (C<SUB>6</SUB>H<SUB>16</SUB>N)[Cr(C<SUB>2</SUB>O<SUB>4</SUB>)<SUB>2</SUB>(H<SUB>2</SUB>O) <SUB>2</SUB>]: Synthesis, Spectroscopic Studies, Thermal Behavior and Crystal Structure

A novel organic-inorganic chromium(III) hybrid salt, triethylammonium trans-diaquabis(oxalato-κ2O1,O2)chromate(III), (C6H16N)[Cr(C2O4)2(H2O)2] (1), has been synthesized in aqueous solution and characterized by elemental and thermal analyses, FTIR and UV-Vis spectroscopies, and by single crystal X-ray structure determination. Compound 1 crystallizes in the orthorhombic system, Pbcn space group with the unit cell parameters a = 11.1776(10), b = 7.6105(10), c = 17.5654(2) Å, α = β = γ = 90°, V = 1494.24(3) Å3, Z = 4 and Z’ = 1/2. The structure of 1 consists of [Cr(C2O4)2(H2O)2]− mononuclear anions and triethylammonium [(C2H5)3NH]+ cations. In the anionic unit, the CrIII ion is six coordinated, in a distorted octahedral geometry, by four equatorial O atoms of two oxalate anions acting as chelating ligands and two O atoms from trans-coordinated water molecules occupying the apical positions with longer metal-oxygen distances. In the solid, O-H … O and N-H … O intra and inter molecular hydrogen bonding interactions connect the components into a 3D network. The triethylammonium cations are disordered among two possible orientations with occupancies rates around 50% for C4, N1, C1a, C1b, C4ii, N1ii, C1aii, C1bii (ii = −x + 1, y, − z + 1/2). The IR spectrum of 1 is consistent with the presence of the various molecular building constituents. The UV-Vis spectrum shows two absorption bands around 564 and 416 nm which are compatible with an anionic chromium (III) complex in an octahedral environment. Thermal studies carried out in air between 25°C and 700°C confirm the anhydrous character of 1 and show that it is stable up to 210°C.

Hybrid Supramolecules for Azolium-Linked Cyclophane Immobilization and Conformation Study: Synthesis, Characterization, and Photocatalytic Degradation.

In this paper, one imidazole macrocyclic divalent cation with a flexible configuration was chosen with the aim of the immobilization of its conformation. Six novel organic–inorganic hybrid supramolecules {([syn/anti-did](CdI4)(C2H3N)} (1), {([syn/anti-did](HgI4)(C2H3N)} (2), {([syn/syn-did](Pb2I8)(PbI5)} (3), {([syn/syn-did](Bi2I8)(BiI5)} (4), {([syn/syn-did](Ag4Br6)}n (5), and {([syn/anti-did](Ag2I4)} (6) [did2+ = (12z, 52z)-11H, 51H-1, 5(1, 3)-diimidazol-3-iuma-3, 7(1, 2)-dibenzenacyclooctaphane-13, 53-diium] have been synthesized through the self-assembly reaction of did2+ with different metals under solvothermal reaction. These compounds have been unambiguously confirmed by powder X-ray diffraction, IR, thermogravimetric and X-ray single-crystal diffraction. Crystallographic analysis shows that the anions of compounds 1 and 2 are isostructural with mononuclear anion structure, the anions of compounds 3, 4, and 6 are of binuclear structure, and compound 5 anion is a one-dimensional anionic chain structure. Imidazole cyclophanes of organic cations may exist in a syn/syn-conformation in 3–5 or syn/anti conformation in 1, 2, 6, but tilting angles in compounds 1–6 were different. This article described the photocatalytic degradation of organic dye in waste water and the optical band gap of compounds 1–6. The calculated semiconductor band gap of compounds 1–6 is smaller than that of TiO2, so compounds 1–6 have semiconductor properties. Compound 1 has the smallest band gap value, and the photocatalytic performance is the best.

Salts of Anionic Metal Carbonyl Clusters with Cryptand[2.2.2](Na+), DB‐18‐crown‐6(Na+), and Paramagnetic Cp*2Cr+ Cations Obtained by Reduction

Reduction of neutral metal clusters (Co4(CO)12, Ru3(CO)12, Fe3(CO)12, Ir4(CO)12, Rh6(CO)16, {CpMo(CO)3}2, {Mn(CO)5}2) by decamethylchromocene (Cp*2Cr) or sodium fluorenone ketyl in the presence of cryptand[2.2.2] and DB‐18‐crown‐6 was studied. Nine new salts with paramagnetic Cp*2Cr+, cryptand[2.2.2](Na+), and DB‐18‐crown‐6(Na+) cations and [Co6(CO)15]2– (1, 2), [Ru6(CO)18]2– (3–4) dianions, [Rh11(CO)23]3– (6) trianions, and new [Ir8(CO)18]2– (5) dianions were obtained and structurally characterized. The increase of nuclearity of clusters under reduction was shown. Fe3(CO)12 preserves the Fe3 core under reduction forming the [Fe3(CO)11]2– dianions in 7. The [CpMo(CO)3]2 and [Mn(CO)5]2 dimers dissociate under reduction forming mononuclear [CpMo(CO)3]– (8) and [Mn(CO)5]– (9) anions. In all anions the increase of negative charge on metal atoms shifts the bands attributed to carbonyl C–O stretching vibrations to smaller wavenumbers in agreement with the elongation of the C–O bonds in 1–9. In contrast, the M–C(CO) bonds are noticeably shortened at the reduction. Magnetic susceptibility of the salts with Cp*2Cr+ is defined by high spin Cp*2Cr+ (S = 3/2) species, whereas all obtained anionic metal clusters and mononuclear anions are diamagnetic. Rather weak magnetic coupling between S = 3/2 spins is observed with Weiss temperature from –1 to –11 K. That is explained by rather long distances between Cp*2Cr+ and the absence of effective π–π interaction between them except compound 7 showing the largest Weiss temperature of –11 K. The {DB‐18‐crown‐6(Na+)}2[Co6(CO)15]2– units in 2 are organized in infinite 1D chains through the coordination of carbonyl groups of the Co6 clusters to the Na+ ions and π–π stacking between benzo groups of the DB‐18‐crown‐6(Na+) cations.

ИССЛЕДОВАНИЕ ЭКСТРАКЦИИ ВОЛЬФРАМА И МОЛИБДЕНА В СИСТЕМАХ С БИНАРНЫМИ ЭКСТРАГЕНТАМИ

The behavior of tungsten and molybdenum in extraction systems with binary extractants is investigated. The role of obtaining tungsten anhydride by purifying waste water from the redistribution is noted. The significance of binary extractants for the extraction of tungsten and molybdenum is underlined. Charts are presented to illustrate the quantitative dependence of the extracted substances. Salts of 4-tert.butylphenolate-, n.-caprylate-, di(2-ethylhexyl) phosphate- and di(2-ethylhexyl) were dithiophosphate trialkylbenzylammonium were used as extractants. Binary extractants have been found to provide efficient extraction and reextraction of tungsten and molybdenum. The maximum extraction of metals is observed at pH = 1–4. At pH> 8, the metals are present in the aqueous phase as mononuclear anions MoO42- and WO42-, and binary extractants are formed in the organic phase. Compared to amines and their salts, the solubility of the binary extractant in aqueous effluent redistribution decreases.

Synthesis, structure and optical properties of two uranyl oxalate complexes templated by protonated amines

[C6H14N]4[UO2(C2O4)2(HC2O4)]NO3·2H2O ( CHA ) and [C8H18N][UO2(C2O4)(NO3)] ( NNDMCHA ) were synthesized by volatile method at room temperature, using [C6H14N]+ and [C8H18N]+ as templates, respectively. The structures and optical properties were characterized by combination of single-crystal X-ray diffraction, PXRD, TG-DSC, IR, Raman, UV-Vis and fluorescence spectra. CHA and NNDMCHA crystallized in monoclinic system, and space group P 21/c. The equatorial coordination number of CHA and NNDMCHA are 5 and 6, respectively, forming pentagonal bipyramid and hexagonal pyramid. The lattice water in CHA formed O–H···O hydrogen bonds with the oxygen atoms of the mononuclear anions, resulting in a s-shaped anion chain which extended along the c direction. The protonated amines were linked to the anion chains by N–H···O and C–H···O hydrogen bonds, leading to form the larger hexagon and the smaller parallelogram pores, respectively. The photoflurescence of two complexes significantly decreased when exposure under UV light, showing potential application for fluorescent sensor.

A series of silver(I) coordination polymers with saccarinate and flexible aliphatic diamines

A series of Ag(I) complexes with aliphatic diamines having a different chain length (NH2-(CH2)n-NH2, n=4–9), with the formulas, [Ag(μ-sac)(μ-db)0.5]n (1), {[Ag4(sac)4(μ-dp)2]·4H2O}n (2), {[Ag2(sac)2(μ-dz)]·2H2O}n (3), {[Ag2(sac)2(μ-dh)]·H2O}n (4), {[Ag2(sac)2(μ-do)]·H2O}n (5a), [Ag2(sac)2(μ-do)2] (5b) and [Ag4(sac)4(μ-dn)2]·2H2O (6), where sac=saccharinate, db=1,4-diaminobutane, dp=1,5-diaminopentane, dz=1,6-diaminohexane, dh=1,7-diaminoheptane, do=1,8-diaminooctane and dn=1,9-diaminononane, were synthesized and characterized by elemental analysis, infrared spectra and single-crystal X-ray diffraction analysis. In 1, the sac ligand bridges adjacent Ag(I) ions through the nitrogen and carbonyl oxygen atoms to form eight-membered bimetallic rings with the Ag···Ag distance being 3.897Å, which are linked by db ligands to give a 1D zigzag chain. The complexes 2–5a consist of a one-dimensional (1D) linear cationic chains and discrete mononuclear anions. The discreet complex units are further connected by ligand unsupported argentophilic interactions. In 6, the dn ligands bridge adjacent silver centers to form 24-membered macrometallacyclic rings, which are further connected to the anionic [Ag(sac)2]- units by argentophilic Ag1···Ag2 interactions to form a tetranuclear structure. The adjacent dinuclear units are further linked together through ligand-unsupported argentophilic Ag···Ag (3.207(1)Å) interactions, generating a one-dimensional linear chain. The most striking feature of complexes is the presence of the rare intermolecular C-H···Ag interactions. In 5b, the do ligand bridges two Ag(I) ions to form a dinuclear with a 22-membered macrometallacyclic ring. Furthermore, biological activities, luminescence properties and thermal analysis (TG/DTA) of the complexes were investigated.

Synthesis, Crystal structure and Characterization of a New Oxalate Chromium (III) Complex

A new hybrid salt (C5H9N2)[Cr(C2O4)2(H2O)2].3H2O, 3,5-dimethylpyrazole Cis diaquadioxalatochromate(III) trihydrate, has been prepared by slow evaporation at room temperature and characterized by single crystal X-ray diffraction, IR, UV–visible spectroscopies, PXRD and thermogravimetric analyses. Furthermore, the observed crystal morphology was compared to the simulated one using the Bravais-Friedel, Donnay-Harker model. The structure of the title compound consists of [Cr(C2O4)2(H2O)2] − mononuclear anions, 3,5-dimethylpyrazole cations and three uncoordinated water molecules. The Cr 3+ ion is six coordinated in a slightly distorted octahedral environment, by two O atoms from two water molecules and four O atoms of two oxalate anions acting as chelating ligands. The cohesion of the structure is established by intermolecular O–H...O, N–H...O hydrogen bonds which connect ionic entities and water molecules and also by π– π stacking interactions between the rings of 3,5-dimethylpyrazole cations. Hence, both coordinated and uncoordinated water molecules play an important role in the hydrogen-bonding system and stabilize the structure. Fragments of the molecular structure of the complex show clearly the intermolecular N–H...O and O–H...O hydrogen bonds between the cation, the complex anion and the lattice water molecules which contribute to the cohesion of the ionic structure, leading to a three dimensional network.

Extended supramolecular structures derived from metal pseudohalides and 4,4′-bipyridinium derivative: Synthesis, structures and optical properties

Four novel extended supramolecular structures based on pseudohalides (SCN) and the flexible cationic ligand 1,4-bis(4,4′-bipyridinium)butane ditetrafluoroborate (bbpyb), namely [bbpyb][Hg(SCN)4] (1), [Cu2(bbpyb)(SCN)4]n (2), [Ag2(bbpyb)(SCN)4]n (3) and [Cu6(bbpyb)(SCN)8]n (4) have been solvothermally synthesized and characterized by IR spectroscopy, thermal gravimetric analysis(TGA), PXRD, UV–Vis diffuse reflectance spectra and single-crystal X-ray diffraction in the solid state. Compound 1 is a 0D supramolecular structure consisted of one linear cationic ligand bbpyb2+ and inorganic mononuclear anion [Hg(SCN)4]2−. Compounds 2 and 3 exhibit infinite two-dimensional anionic architecture, which represent the same (6,3) topology. In compound 4, the cationic ligand bbpyb2+ bridge [Cu6(SCN)8] cluster unit to generate a 3D coordination framework. The structural diversities show that the pseudohalides (SCN) and cationic ligand should very likely be excellent candidates to construct higher dimensional extend supramolecular architectures. In addition, the optical band gap and photocatalytic properties of compounds 1–4 were also investigated.

Synthesis, crystal structures and characterization of two heterometallic compounds: Ba3[Fe(C2O4)3]2(H2O)12 and Ba4.5[Fe4O(OH)3(C2O4)8](H2O)19

Heterometallic yellow compound Ba3[Fe(C2O4)3]2(H2O)12 (1) with mononuclear anion [Fe(C2O4)33−] can be transformed to heterometallic red compound Ba4.5[Fe4O(OH)3(C2O4)8](H2O)19 (2) with OH/O bridged tetranuclear anion [Fe4O(OH)3(C2O4)89−] in the mother liquor. Ba2+ and Fe3+ form three-dimensional networks thorough oxalate anion and H2O molecules in 1 and 2. 1 is a paramagnet and a strong antiferromagnetic interaction as the ground state S=0 exists in 2.

Six cation-templated halometal complexes and C–H activation of alkylene-bridged azoles

Six dication-templated complexes were discovered in efforts to investigate the effect of linear imidazolium-based template, 1,ω-bis(3,3′-methylimidazolium)alkyl dibromide, on pure inorganic halometal clusters. Complexes {[C4(Mim)2](Pb2I6)}n (1) (ω = 4), {[C1(Mim)2] (Ag2I4)}n (2) (ω = 1), {[C3(Mim)2](Ag2I4)}n (3) (ω = 3), and {[C4(Mim)2](Ag2I4)}n (4) (ω = 4) possess 1-D chain architecture with different organic cations trapped in it. Compound {[C3′(Mim)2](CuBr3)} (5) (ω = 3) contains the mononuclear anion (CuBr3)2− and intra-molecular coupled organic cation with the formed seven-membered ring. {[C2(Mim)2S2]2(Cu2I2)}n (6) (ω = 2) presents an infinite 2-D coordination polymer as the first representative polyrotaxane example featuring the biimidazolium thiolate cation ligand. All compounds were further characterized with IR spectra and thermal analysis properties.

Synthesis and structure of palladium complexes [Ph3PhCH2P]+[PdCl3(DMSO)]− · DMSO, [Ph4P]+[PdCl3(DMSO)]−, and [Ph4Sb(DMSO)]+[PdCl3(DMSO)

[Ph3PhCH2P]+[PdCl3(DMSO)]− · DMSO (I), [Ph4P]+[PdCl3(DMSO)]− (II), and [Ph4Sb(DMSO)]+[PdCl3(DMSO)]− (III) complexes have been synthesized via the reaction of palladium chloride with equimolar amounts of triphenylbenzylphosphonium chloride, tetraphenylphosphonium chloride, and tetraphenylstibonium chloride, respectively. According to X-ray diffraction data, the cations of complexes I (CPC = 104.90(8)°–111.61(9)°) and II (CPC = 105.12(10)°–111.46(10)°) have slightly distorted tetrahedral structures with P-C bond lengths of 1.786(2)–1.809(2) and 1.791(2)–1.799(2) A, respectively. The antimony atom in the [Ph4Sb(DMSO)]+ cation has a trigonal bipyramidal surrounding with the dimethyl sulfoxide (DMSO) oxygen atom in an axial position (Sb...O 2.567(2) A). The palladium atoms in the square mononuclear anions of complexes I, II, and III are tetracoordinate, and Pd-Cl distances are 2.3101(5)–2.3104(5) A, 2.2950(7)–2.2038(7) A, and 2.2986(9)–2.3073(9) A, respectively. The DMSO ligands are coordinated to the palladium atom through the sulfur atom (Pd-S, 2.2318(5) (I), 2.2383(6) (II), and 2.2410(9) A (III)).

Two Systems of [DabcoH2]2+/[PipH2]2+–Uranyl–Oxalate Showing Reversible Crystal-to-Crystal Transformations Controlled by the Diammonium/Uranyl/Oxalate Ratios in Aqueous Solutions ([DabcoH2]2+ = 1,4-Diazabicyclo-[2.2.2]-octaneH2 and [PipH2]2+ = PiperazineH2)

We present here two systems of [dabcoH2]2+–uranyl–oxalate and [pipH2]2+–uranyl–oxalate in which [dabcoH2]2+ and [pipH2]2+ are cations of doubly protonated 1,4-diazabicyclo-[2.2.2]-octane (dabco) and piperazine (pip), respectively. Each system yielded two different crystals and showed the reversible crystal-to-crystal transformations between them in aqueous solutions, controlled by the ratio of reactants or building blocks in the reaction systems. The four compounds in pairs are [dabcoH2][UO2(C2O4)2(H2O)]·2H2O (dabco1) and [dabcoH2][(UO2)2(C2O4)3(H2O)2]·2H2O (dabco2), and [pipH2][UO2(C2O4)2(H2O)]·4H2O (pip1) and [pipH2][(UO2)2(C2O4)3(H2O)2]·2H2O (pip2). Besides the cations and lattice water, dabco1 and pip1 contain mononuclear anions of [UO2(C2O4)2(H2O)]2–, whereas dabco2 and pip2 possess dinuclear anions of [(UO2)2(C2O4)3(H2O)2]2–, and in all structures, the uranium ion shows a pentagonal bipyramid environment made up of equatorial oxalate, water, and apical oxygen. The needle crystals of dabco1 belong to the chiral space group P6522. In the structure, the [UO2(C2O4)2(H2O)]2– anions form anionic helixes along the 65 axis and they are further linked by N–H···O hydrogen bonds between the interhelix [dabcoH2]2+ cation and oxalates of the anion. Disorder of lattice water and the [dabcoH2]2+ cation is observed in dabco1. The thin plate crystals of pip1 in space group P1̅ possess a lamellar structure, with dense layers of [pipH2]2+·2[UO2(C2O4)2(H2O)]2– pillared by other crystallographically unique [pipH2]2+ cations, and the structure contains lattice water forming branched zigzag water chains. Block crystals of dabco2 and pip2, in monoclinic space groups C2/c and P21/c, respectively, are of similar layer-like structures, possessing the dinuclear [(UO2)2(C2O4)3(H2O)2]2– anion with one tetradentate oxalate bridge. The anions and ammonium cations form chains by N–H···O hydrogen bonds between them and then further form stacked layers via O–H···O hydrogen bonds among the coordinated and lattice water and the oxalate ligands. The ratio of diammonium/uranyl/oxalate in the reaction systems controlled the final outcomes and the occurrence of transformation, no transformation, and reverse transformation. The thermal stability; UV–vis, IR, and Raman spectra; and luminescence were also investigated.

A new bis(oxalato)chromate(III) salt: synthesis, crystal structure, thermal behavior and magnetic properties of (C3H5N2)[Cr(C2O4)2(H2O)2].2H2O

A new chromium(III) salt (C3H5N2)[Cr(C2O4)2(H2O)2].2H2O, trans-diaquabis(oxalato) chromate(III) imidazolium dihydrate, has been synthesized and characterized by single crystal X-ray diffraction. This compound crystallizes in the monoclinic system, C2/c space group with a = 10.836(1)Å, b = 7.541(1)Å, c = 16.349(3)Å and β = 93.52(1)°. The structure of the title compound consists of [Cr(C2O4)2(H2O)2]− mononuclear anions, imidazolium cations and uncoordinated water molecules. The crystal structure data indicates that the Cr +III ion is six coordinated in a distorted octahedral geometry, with four equatorial O atoms of two oxalate anions acting as chelating ligands and two axial O atoms from two water molecules. Structural cohesion is established by intermolecular O–H…O hydrogen bonds connecting the ionic entities and water molecules. In fact, both coordinated and uncoordinated water molecules play an important role in the hydrogen-bonded system, stabilizing the structure. Magnetic susceptibility measurements of the title compound in the range 2-300K exhibit paramagnetic behavior at high temperature. However, at low temperature, the magnetic data show the occurrence of weak antiferromagnetic intermolecular interactions between the local spin.

Hydrothermal Syntheses, Crystal Structures, and Fluorescent Properties of Zn(II) Coordination Complexes With 4-Amino-3,5-Bis(2-Pyridyl)-1,2,4-Triazole and Different Aromatic Dicarboxylic Acids

Three new Zn(II) supramolecular complexes {[Zn(2-bpt)(tp)(H2O)](H2O)}∞ (1), [Zn(2-bpt)2(Hpa)2] (2), and [Zn(2-bpt)2(H2O)2](Hip-NO2)2 (3) have been synthesized under hydrothermal conditions by using 4-amino-3,5-bis(2-pyridyl)- 1,2,4-triazole (2-bpt) and Zn(OAc)2 with the presence of different aromatic dicarboxylic acids (H2tp = terephthalic acid, H2pa = phthalic acid, and H2ip–NO2 = 5-nitroisophthalic acid). Complex 1 shows a one-dimensional zigzag chain array, 2 represents a neutral mononuclear molecule, and 3 consists of the cationic mononuclear coordination unit and Hip-NO2 anion. Notably, in complex 3, the H2ip–NO2 ligand is partly deprotonated to balance the charge and uncoordinated to the metal center. In all three structures, the low-dimensional coordination motifs are further extended to distinct two-dimensional or three-dimensional supramolecular networks via H-bonding and/or π···π stacking interactions. Fluorescent properties for 1–3 have also been studied in solid state at room temperature.

Halide and Hydroxide Linearly Bridged Bimetallic Copper(II) Complexes: Trends in Strong Antiferromagnetic Superexchange Interactions

Centrosymmetric [Cu(2)(μ-X)(μ-L(m)*)(2)](ClO(4))(3) (X = F(-), Cl(-), Br(-), OH(-), L(m)* = m-bis[bis(3,5-dimethyl-1-pyrazolyl)methyl]benzene)], the first example of a series of bimetallic copper(II) complexes linked by a linearly bridging mononuclear anion, have been prepared and structurally characterized. Very strong antiferromagnetic exchange coupling between the copper(II) ions increases along the series F(-) < Cl(-) < OH(-) < Br(-), where -J = 340, 720, 808, and 945 cm(-1). DFT calculations explain this trend by an increase in the energy along this series of the antibonding antisymmetric combination of the p orbital of the bridging anion interacting with the copper(II) d(z(2)) orbital.

Theoretical Insights into the Ferromagnetic Coupling in Oxalato-Bridged Chromium(III)-Cobalt(II) and Chromium(III)-Manganese(II) Dinuclear Complexes with Aromatic Diimine Ligands

Two novel heterobimetallic complexes of formula [Cr(bpy)(ox)(2)Co(Me(2)phen)(H(2)O)(2)][Cr(bpy)(ox)(2)]·4H(2)O (1) and [Cr(phen)(ox)(2)Mn(phen)(H(2)O)(2)][Cr(phen)(ox)(2)]·H(2)O (2) (bpy = 2,2'-bipyridine, phen = 1,10-phenanthroline, and Me(2)phen = 2,9-dimethyl-1,10-phenanthroline) have been obtained through the "complex-as-ligand/complex-as-metal" strategy by using Ph(4)P[CrL(ox)(2)]·H(2)O (L = bpy and phen) and [ML'(H(2)O)(4)](NO(3))(2) (M = Co and Mn; L' = phen and Me(2)phen) as precursors. The X-ray crystal structures of 1 and 2 consist of bis(oxalato)chromate(III) mononuclear anions, [Cr(III)L(ox)(2)](-), and oxalato-bridged chromium(III)-cobalt(II) and chromium(III)-manganese(II) dinuclear cations, [Cr(III)L(ox)(μ-ox)M(II)L'(H(2)O)(2)](+)[M = Co, L = bpy, and L' = Me(2)phen (1); M = Mn and L = L' = phen (2)]. These oxalato-bridged Cr(III)M(II) dinuclear cationic entities of 1 and 2 result from the coordination of a [Cr(III)L(ox)(2)](-) unit through one of its two oxalato groups toward a [M(II)L'(H(2)O)(2)](2+) moiety with either a trans- (M = Co) or a cis-diaqua (M = Mn) configuration. The two distinct Cr(III) ions in 1 and 2 adopt a similar trigonally compressed octahedral geometry, while the high-spin M(II) ions exhibit an axially (M = Co) or trigonally compressed (M = Mn) octahedral geometry in 1 and 2, respectively. Variable temperature (2.0-300 K) magnetic susceptibility and variable-field (0-5.0 T) magnetization measurements for 1 and 2 reveal the presence of weak intramolecular ferromagnetic interactions between the Cr(III) (S(Cr) = 3/2) ion and the high-spin Co(II) (S(Co) = 3/2) or Mn(II) (S(Mn) = 5/2) ions across the oxalato bridge within the Cr(III)M(II) dinuclear cationic entities (M = Co and Mn) [J = +2.2 (1) and +1.2 cm(-1) (2); H = -JS(Cr)·S(M)]. Density functional electronic structure calculations for 1 and 2 support the occurrence of S = 3 Cr(III)Co(II) and S = 4 Cr(III)Mn(II) ground spin states, respectively. A simple molecular orbital analysis of the electron exchange mechanism suggests a subtle competition between individual ferro- and antiferromagnetic contributions through the σ- and/or π-type pathways of the oxalato bridge, mainly involving the d(yz)(Cr)/d(xy)(M), d(xz)(Cr)/d(xy)(M), d(x(2)-y(2))(Cr)/d(xy)(M), d(yz)(Cr)/d(xz)(M), and d(xz)(Cr)/d(yz)(M) pairs of orthogonal magnetic orbitals and the d(x(2)-y(2))(Cr)/d(x(2)-y(2))(M), d(xz)(Cr)/d(xz)(M), and d(yz)(Cr)/d(yz)(M) pairs of nonorthogonal magnetic orbitals, which would be ultimately responsible for the relative magnitude of the overall ferromagnetic coupling in 1 and 2.

Chloride Coordination by Oligoureas: From Mononuclear Crescents to Dinuclear Foldamers

A series of acyclic oligourea receptors which closely resemble the scaffolds and coordination behavior of oligopyridines have been synthesized. Assembly of the receptors with chloride ions afforded mononuclear anion complexes or dinuclear foldamers depending on the number of the urea groups.

Role of cooperative templates in the self-assembly process of microporous structures: syntheses and characterization of 12 new silver halide/thiocyanate supramolecular polymers

12 new cation-templated complexes, {(BMPB)[AgI3]} (BMPB = 1, 4-bis (methylpyridinium) benzene) (1), {(BPE)2[Ag2I6]} (BPE = 1, 2-bis (pyridinium) ethane) (2), {(BPB)[Ag2I4]} (BPB = 1, 4-bis (pyridinium) butane) (3), {(BPH)[Ag2I4]} (BPH = 1, 7-bis (pyridinium) heptane) (4), {(DIBP)[Ag2I4]} (DIBP = 1, 1′-diisopropyl-4, 4′-bipyridinium) (5), {(BPB)[Ag2Br4]} (6), {(BPP)[Ag2Br4]} (=1, 5-bis (pyridinium) pentane) (7), {(DEBP)[Ag2Br4]} (DEBP = 1, 1′-diethyl-4, 4′-bipyridinium) (8), {(BDMLB)[Ag2Br4]} (BDMLB = 1, 4-bis (dimethylimidazolium) butane) (9), {(BPIB·Br)[Ag(NCS)2]} (BPIB·Br = butane phenanthroline bromide) (10), {(DABP)[Ag4I6]} (DABP = 1, 1′-diamyl-4, 4′-bipyridinium) (11), {(BMLB)[Ag2Br2(NCS)2]} (BMLB = 1, 4-bis (methylimidazolium) butane) (12), have been synthesized via the self-assembly reaction in solution. Owing to the cooperative template effects from organic cations and halide/thiocyanate anion compounds 1–11 contain a mononuclear anion structure [AgI3]2− (1), a dimeric anion [Ag2I6]4− (2), linear chain [Ag2X4]2− (3–10) and a cubane-like based one-dimensional anionic chain [Ag4I6]2− (11) that are enclosed into the different cationic channels formed from the pyridinium, phenanthrolinium and imidazolium. While for 12, the compound possesses an infinite 2D supramolecular polypseudorotaxane penetrated by geminal dicationic groups.