Ethylene glycol-modified cobalt and iron oxalates as precursors for the synthesis of oxides as extended microsized and nanosized objects

The reactions of ethylene glycol with iron and cobalt oxalates upon heating in air are reported. Heat treatment of mixtures of oxalate powders with ethylene glycol yields new compounds (solvates) via the replacement of the water molecules in the oxalate structure by ethylene glycol molecules: MC₂O₄ · 2H₂O + HOCH₂CH₂OH = MC₂O₄(HOCH₂CH₂OH)+2H₂O↑. The crystals resulting from this reaction are elongated, and their shape is inherited by their thermolysis products. Thermolysis in air yields microwhiskers and nanowhiskers of Fe₂O₃ and Co₃O₄, and thermolysis in an inert atmosphere affords Fe₃O₄ and Co whiskers. The thermolysis of FeC₂O₄(HOCH₂CH₂OH) in helium yields a new structural modification of FeC₂O₄ as an intermediate product. The resulting compounds and their thermolysis products were characterized by X-ray powder diffraction, microscopy, IR spectroscopy, and thermogravimetric and chemical analyses. The particle shape and size were determined by scanning electron microscopy.     

Effect of ethylene glycol on the formation of extended crystals of M1/3Co2/3C2O4 · 2H2O (M = Zn, Mn) oxalates and their thermolysis products

The effect of ethylene glycol (EG) on the formation of whiskers and fibers of complex oxides with the general formula MCo₂O₄ upon the thermolysis of M_1/3Co_2/3C₂O₄ (M = Zn, Mn) oxalates has been studied. New compounds (solvates) are formed when powdered oxalates are heated with EG. In the solvates, EG molecules substitute for water molecules according to the reaction M_1/3Co_2/3C₂O₄ · 2H₂O + HOCH₂CH₂OH = M_1/3Co_2/3C₂O₄(HOCH₂CH₂OH) + 2H₂O. The solvates have been characterized using X-ray powder diffraction, microscopy, IR spectroscopy, thermogravimetry, and chemical analysis. The shape, structure, and particle size of the thermolysis products of EG-modified oxalates have been determined using scanning electron microscopy.     

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.     

Oxalate-2-ethanolamine complexes of some bivalent cations (Mn,Co, Ni,Cu, Zn and Cd)

On the refluxing ofM(II) oxalate (M=Mn, Co, Ni, Cu, Zn or Cd) and 2-ethanolamine in chloroform, the following complexes were obtained: MnC₂O₄·HOCH₂CH₂NH₂·H₂O, CoC₂O₄·2HOCH₂CH₂NH₂, Ni₂(C₂O₄)₂·5HOCH₂CH₂NH₂·3H₂O, Cu₂(C₂O₄)₂·5HOCH₂CH₂NH₂, Zn₂(C₂O₄)₂·5HOCH₂CH₂NH₂·2H₂O and Cd₂(C₂O₄)₂·HOCH₂CH₂NH₂·2H₂O. Following the reaction ofM(II) oxalate with 2-ethanolamine in the presence of ethanolammonium oxalate, a compound with the empirical formula ZnC₂O₄·HOCH₂CH₂NH₂·2H₂O¹ was isolated. The complexes were identified by using elemental analysis, X-ray powder diffraction patterns, IR spectra, and thermogravimetric and differential thermal analysis. The IR spectra and X-ray powder diffraction patterns showed that the complexes obtained were not isostructural. Their thermal decompositions, in the temperature interval between 20 and about 900°C, also take place in different ways, mainly through the formation of different amine complexes. The DTA curves exhibit a number of thermal effects.     

Separate Crystallization of Lanthanide Oxalates and Calcium Oxalates from Nitric Acid Solutions

The separation of lanthanides from calcium compounds in the form of oxalates from hot nitric acid solutions of Ln(NO₃)₃ and Ca(NO₃)₂ with the insertion of oxalic acid and a Ln₂(C₂O₄)₃ · nH₂O crystal seed was studied by mass-spectrometric, atomic emission, microscopic, X-ray diffraction, and fluorescence analyses. The produced single-phase precipitate was found to contain an isomorphic impurity of La–Sm oxalates, while calcium oxalate remained in the hot nitric acid solution (95°С) saturated with oxalic acid. This facile and efficient method provides Ln₂(C₂O₄)₃ · nH₂O (n = 9.5 mol) in one step in a 80.1 rel. % yield, with the major phase being at least 99.4 wt %. The unit cell parameters were determined for the crystals of the isomorphic lanthanide oxalate mixture: a = 11.243(2) Å, b = 9.591(2) Å, c = 10.306(2) Å; α = γ = 90°, β = 114.12(1)°; Z = 2; V = 1013.7(5) ų.     

Synthesis,structures, and magnetic properties of two closely-related manganese(II) coordination polymers

The reactions of Mn²⁺ ion with 4-nitrobenzene-1,2-bicarboxylic acid in the presence of bipyridyl-type coligands gave two new manganese(II) coordination polymers, [Mn₂(Nbdc)₂(Bipyp)(H₂O)₄] _n (I) and [Mn₂(Nbdc)₂(Bipye)(H₂O)₄] _n (II) (H₂Nbdc = 4-nitrobenzene-1,2-bicarboxylic acid, Bipyp = 1,3-bi(4-pyridyl)propane, and Bipye = 1,2-bi(4-pyridyl)ethane). Both two complexes contain uniform carboxyl-bridged manganese chains with the composition of [Mn₂(Nbdc)₂(H₂O)₄] _n , which are interlinked by interchain Bipyp/Bipye spacers to afford two closely-related layers (CIF files CCDC nos. 1008182 (I) and 1008183 (II)). Magnetic studies for two compounds show the presence of similar antiferromagnetic couplings between the adjacent Mn²⁺ ions through the carboxyl bridges, the best fittings to the experimental magnetic susceptibilities gave J =–0.20 cm^–1 and g = 1.96 for I, and J =–0.24 cm^–1 and g = 1.98 for II. Similar magnetic parameters and thermal behaviors further verify that two compounds possess closely-related structures.     

Synthesis, crystal structures, and magnetic properties of two three-dimensional octacyanotungstate(IV)- based bimetallic frameworks with 4,4′-bipyridine dioxide (4,4′-dpdo)

The reaction of [HN(n-C4H9)3]3[WV(CN)8]·4H2O, 4,4′-bipyridine dioxide(4,4′-dpdo), and MnCl2·4H2O or CuCl2·2H2O gives two new three-dimensional octacyanometalate-based bimetallic assemblies, {[Mn2 (4,4′-dpdo)(H2O)4] [WIV(CN)8]}·6H2O (1) and {[Cu2(4,4′-dpdo)(H2O)][W(CN)8]}·CH3OH·H2O (2). Compound 1 crystallizes in the orthorhombic system, space group P21212 with cell constants a=10.397(2) -, b= 11.321(2) -, c=12.295(3) - and Z=2, whereas 2 crystallizes in the monoclinic system, space group P21/c with cell con...     

Synthesis,crystal structure,and magnetic characterization of two manganese Schiff-base-containing complexes

The reactions of [Mn^III(3-MeOSalen)(H₂O)₂]⁺ (Salen = N,N-ethylenebis(salicylideneaminato) dianion) with (Et₄N)₄[M(CN)₈] (M = Mo, W) have been investigated and one mononuclear manganese(II) complex [Mn^II(Salen)(H₂O)] (I) and one bimetallic ion-pair complex [Mn^III(3-MeO-Salen)(H₂O)₂]₄[W(CN)₈] · DMSO · 4H₂O (II) were obtained unexpectedly and characterized by element and single crystal structure analysis. Single crystal X-ray diffraction (CIF files CCDC nos. 1456365 (I) and 1456366 (II)) showed that the Mn²⁺ ion in complex I is five-coordinated involving in a distorted square pyramid. Furthermore, with the help of the intermolecular hydrogen bond interactions, this complex can be constructed into interesting one-dimensional zig-zag chain structure. For complex II, the coordination sphere of Mn³⁺ ion is an elongated octahedron. Additional, the four mononuclear manganese(III) units are self-complementary through the coordinated aqua ligand from one molecule and the free O(4) compartment from the neighboring molecule, giving supramolecular dimmers structure. Investigation of the magnetic susceptibility of the two complexes reveals the overall weak antiferromagnetic interactions between the adjacent manganese centers caused by H-bond interactions.     

Disproportionation of manganese(II) (1-hydroxyethylidene) diphosphonate in reaction with 2-aminoethanol

Reaction of poorly soluble manganese(II) bis(1-hydroxyethylidene)diphosphonate tetrahydrate Mn(H₃L)₂ · 4H₂O with 2-aminoethanol H₂NCH₂CH₂OH in an aqueous solution on heating to 70–80°C causes the initial formation of soluble tris(2-hydroxyethanaminium) manganese(II) bis(1-hydroxyethylidene) diphosphonate Mn(H₃L)₂ · 3H₂NCH₂CH₂OH · 4H₂O, which next disproportionates into poorly soluble 2-hydroxyethanaminium manganese(II) (1-hydroxyethylidene)diphosphonate MnH₂L · H₂NCH₂CH₂OH and metal-cation-free coordination polymer of (1-hydroxyethylidene)diphosphonic acid with 2-aminoethanol. Poorly soluble MnH₂L · H₂NCH₂CH₂OH can be readily converted into the soluble form by treatment with 2-aminoethanol or 2-amino-2-(hydroxymethyl)propane-1,3-diol H₂NC(CH₂OH)₃.     

Two bimetallic W(IV)-Mn(II) complexes based on octacyanometallates: structures and magnetic properties

Two cyano-bridged heterobimetallic coordination polymers, [{Mn(dpa)₂}₂W(CN)₈·CH₃CN·₄H₂O] _n (1) (dpa = 2,2′-dipyridylamine) and [Mn₂(H₂O)₄{W(CN)₈}·3H₂O] _n (2), have been synthesized and characterized structurally and magnetically. X-ray analysis shows that complex 1 is a one-dimensional (1-D) polymer of W₂(CN)₄Mn₂ square units in which adjacent square fragments are interlinked by sharing [W(CN)₈]^4? moieties to form an infinite chain. Complex 2 is a three-dimensional (3-D) polymer, which shows an unforeseen structure, exhibiting a 3-D open network with a 1-D channel (ca.13.21 Å × 11.82 Å). Fitting of the magnetic properties indicates that both polymers exhibit weakly antiferromagnetic interactions between the adjacent Mn ions.     

Phase composition,formation parameters,and morphology of precipitates in the LiVO<Subscript>4</Subscript>-VOSO<Subscript>4</Subscript>-H<Subscript>2</Subscript>O system

The phase and chemical compositions of the precipitates formed in the LiVO₃-VOSO₄-H₂O system at initial pH within 1 ≤ pH ≤ 4 and 90°C were studied. The following phases were prepared: an α phase Li_1.4(VO)_1.3[H₂V₁₀O₂₈] · nH₂O and a β phase Li_{0.6 ? x} H_{1.4 + x} [V₁₂O_{31 ? y/2}] · nH₂O (0 ≤ x ≤ 0.5, 1.3 ≤ y ≤ 2.0) with a layered structure. Li_0.4V₂O₅ · H₂O nanorods with the interlayer distance 10.30 ± 0.08 Å were synthesized at 180°C in an autoclave. The morphology, IR spectra, and main formation processes for these polyvanadates were studied.     

Calcium peroxosilicates

Calcium peroxosilicates CaO·nSiO₂·xH₂O·yH₂O₂ (n = 1, 2) were synthesized by three methods: (1) the reaction of CaSiO₃·nH₂O (～7% CaSiO₃ suspension in water) with 50.7, 73.4, and 92% H₂O₂ at 0–5°C produced compositions CaSiO₃·6H₂O·2H₂O₂, CaSiO₃·2H₂O·4H₂O₂, and CaSiO₃·3H₂O·8H₂O₂, respectively; (2) the reaction of CaSiO₃·17H₂O with 50.7 and 73.4% H₂O₂ at 0–5°C produced the solvate CaO·2SiO₂·4H₂O·0.15H₂O₂; and (3) the reaction of CaSiO₃·3H₂O with H₂O₂ vapor at 5°C in the absence of anhydrone produced the solvate CaSiO₃·3.5H₂O·0.5H₂O₂. The products were characterized by X-ray powder diffraction, thermogravimetry, and IR spectroscopy.     

Synthesis and study of solid solutions between cobalt and nickel phosphates with varied degree of anion protonation

Continuous substitutional solid solutions between cobalt and nickel phosphates with varied degree of anion protonation were obtained: Co_1?x Ni _x HPO₄·1.5H₂O and (Co_1?x Ni _x )₃(PO₄)₂·8H₂O, where 0 ≤ x ≤ 1.00. The thermolysis of the solid solutions was studied by the example of Co_1?x Ni _x HPO₄·1.5H₂O. The phases synthesized were compared with the previously described continuous solid solution Co_1?x Ni _x (H₂PO₄)₂·2H₂O.     

Catalytic Properties of Heteropolytungstates with 3<Emphasis Type="Italic">d</Emphasis> Elements and Their Thermolysis Products

The catalytic properties of the potassium salts of heteropolytungstates with the general formulas K_m[X₂W₁₁(H₂O)O₃₉] (X = Fe³⁺, Co²⁺, and Zn²⁺) and K₅[H₂W₁₁Cr(H₂O)₂O₃₈] with the Keggin anion structure and K_n[XH_nW₆O₂₄] (X = Ni²⁺ and Mn⁴⁺) with the Anderson anion structure and their thermolysis products were studied in the reaction of isopropanol oxidation to acetone by atmospheric oxygen. Changes in their catalytic properties depending on their constituent 3d elements were established. The test heteropolytungstates and the thermolysis products of their potassium salts—phases with the structures of the types of pyrochlore and hexagonal tungsten bronzes—are promising compounds for the preparation of catalysts for organic synthesis reactions. The results of the studies can be useful for the prognostication of the properties of new catalytic systems based on these compounds.     

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.     

Two New One-Dimensional Chain-Like Compounds Constructed from the Sandwich-Type Polyoxotungstate Clusters

Two new one-dimensional chain-like compounds, K₄Na₄[Mn₂(H₂O)₈Mn₄(H₂O)₂(GeW₉O₃₄)₂] · 20.5H₂O (1) and K₂Na₄Cu₂(H₂O)₁₂[Cu(H₂O)₂Cu₄(H₂O)₂(SiW₉O₃₄)₂] · 15H₂O (2), constructed from the sandwich-type clusters, have been obtained by the routine synthetic reactions in aqueous solutions, and their structures were determined by X-ray single crystal diffraction analysis. The crystal data is following: for 1, space group, monoclinic, P _21/n, a = 16.693(3) Å, b = 14.935(3) Å, c = 20.090(4) Å, β = 92.23(3)°, V = 5004.7(17) ų, Z = 2; For 2, space group, triclinic, P _?1, a = 11.744(2) Å, b = 13.415(3) Å, c = 17.609(4) Å, α = 73.08(3)°, β = 82.68(3)°, γ = 65.18(3)°, V = 2409.1(8) ų, Z = 1. The crystal structure of 1 shows a 1D ladder-like chain, built up of the sandwich anions [Mn₄(H₂O)₂(GeW₉O₃₄)₂]^12? and the Mn²⁺ ions. Compound 2 is a polymeric chain, composed of the Cu-substituted sandwich-type anions [Cu₄(H₂O)₂(SiW₉O₃₄)₂]^12? linked by the Cu(H₂O)₄ clusters. These extended materials based on the sandwich-type polyoxoanions are rarely reported in the POM chemistry.     

Effect of hydrothermal and ultrasonic/hydrothermal treatment on the phase composition and micromorphology of yttrium hydroxocarbonate

The effect of hydrothermal and ultrasonic/hydrothermal treatment on the phase composition and micromorphology of yttrium hydroxocarbonates has been studied. The hydrothermal treatment of a suspension of amorphous yttrium hydroxocarbonate hydrate, Y(OH)CO₃ · 1.25H₂O, does not significantly alter the composition of the powder, while ultrasonication directly in the course of hydrothermal treatment under the same conditions yields crystalline yttrium hydroxocarbonate Y(OH)CO₃. The thermolysis of yttrium hydroxocarbonates Y(OH)CO₃ · xH₂O and Y(OH)CO₃ has been studied.     

New approach to the synthesis of polynuclear heterometallic pivalates with iron and manganese atoms

New hexanuclear Fe(III)–Mn(II, III) pivalates [Fe₂ ^III Mn₄ ^II(O)₂(Piv)₁₀(HPiv)₄] (I) or [Fe₄ ^III Mn₂ ^III(O)₂(Piv)₁₂(CH₂O₂)(HPiv)₂] · Et₂O (II) are synthesized using the solid-state thermolysis of [Fe₂Mn(O)(Piv)₆(HPiv)₃] (90°С). Complexes I and II differ by the ratio of iron and manganese ions, which depends on the atmospheric composition during thermolysis. The structures of compounds I and II are determined by X-ray diffraction studies. According to the parameters of the Mössbauer spectrum, complex I contains the Fe³⁺ ions in the high-spin state in the octahedral environment of oxygen atoms.     

New binuclear complex of bis(2,4,6,8-tetramethyl-2,4,6,8- tetraazabicyclo(3.3.0)octane-3,7-dione-<Emphasis Type="Italic">O,O</Emphasis>')-diaquatetrakis(nitrato-<Emphasis Type="Italic">O,O</Emphasis>')-dimanganese(II) monohydrate: Synthesis and crystal structure

The centrosymmetric binuclear manganese(II) nitrate complex with a bicyclic bis-carbamide, namely, 2,4,6,8-tetramethyl-2,4,6,8-tetraazabicyclo(3.3.0)octane-3,7-dione, or mebicar (Mk) [Mn(C₈H₁₄N₄O₂)(H₂O)(NO₃)₂]₂ · H₂O (I), has been synthesized for the first time. The structure of complex I has been solved (CCDC no. 1435139). Crystals of complex I are monoclinic, space group P2₁/c, a = 12.8108(11) Å, _b = 10.0662(2) Å, c = 18.6367(17) Å, β = 136.512(16)°, V = 1654.0(4) ų, ρcalcd = 1.659 g/cm³, Z = 2. Each manganese atom is coordinated to the two oxygen atoms of two Mk molecules related by the symmetry codes (1–x, 2–y, 1–z) and to two bidentate nitrate anions and one water molecule. The coordination polyhedron of the manganese atom is a strongly distorted pentagonal bipyramid. The Mn···Mn distance in the complex is 8.7261(9) Å.     

A mononuclear nickel(II) complex and a dinuclear manganese(III) complex derived from N,N'-bis(5-methoxysalicylidene)-1,2-ethanediamine: Synthesis,crystal structures and catalytic epoxidation property

Synthesis and characterization of a mononuclear nickel(II) complex [NiL] · CH₃OH (I) and a dinuclear manganese(III) complex [Mn₂L₂(NCS)₂] (II) derived from the bis-Schiff base N,N'-bis(5-methoxysalicylidene)-1,2-ethanediamine (H₂L) are reported. The complexes were characterized by elemental analyses, IR spectra and molar conductivity. Single crystal X-ray structures of the complexes have been determined (CIF files CCDC nos. 1056778 (I) and 1056688 (II)). The Ni atom in I is in a square planar coordination, and the Mn atom in II is in an octahedral coordination. Catalytic property for epoxidation of styrene by the complexes using PhIO and NaOCl as oxidant has been studied. As a result, complex II is efficient for the styrene epoxidation.