Synthese,Kristallstrukturen und thermisches Verhalten von Er2(SO4)3 · 8 H2O und Er2(SO4)3 · 4 H2O

Syntheses, Crystal Structures, and Thermal Behavior of Er₂(SO₄)₃ · 8 H₂O and Er₂(SO₄)₃ · 4 H₂O Evaporation of aqueous solutions of Er₂(SO₄)₃ yields light pink single crystals of Er₂(SO₄)₃ · 8 H₂O. X-ray single crystal investigations show that the compound crystallizes monoclinically (C2/c, Z = 8, a = 1346.1(3), b = 667.21(1), c = 1816.2(6) pm, β = 101.90(3)°, R_all = 0.0169) with eightfold coordination of Er³⁺, according to Er(SO₄)₄(H₂O)₄. DSC- and temperature dependent X-ray powder investigations show that the decomposition of the hydrate follows a two step mechanism, firstly yielding Er₂(SO₄)₃ · 3 H₂O and finally Er₂(SO₄)₃. Attempts to synthesize Er₂(SO₄)₃ · 3 H₂O led to another hydrate, Er₂(SO₄)₃ · 4 H₂O. There are two crystallographically different Er³⁺ ions in the triclinic structure (P 1, Z = 2, a = 663.5(2), b = 905.5(2), c = 1046.5(2) pm, α = 93.59(3)°, β = 107.18(2)°, γ = 99.12(3)°, R_all = 0.0248). Er(1)³⁺ is coordinated by five SO₄^2– groups and three H₂O molecules, Er(2)³⁺ is surrounded by six SO₄^2– groups and one H₂O molecule. The thermal decomposition of the tetrahydrate yields Er₂(SO₄)₃ in a one step process. In both cases the dehydration produces the anhydrous sulfate in a modification different from the one known so far.     

Thermal behavior of some compounds of methanesulfonic acid with transition metals

The following compounds of methanesulfonic acid, CH₃SO₃H, have been prepared: Cu(CH₃SO₃)₂ · 4 H₂O; Zn(CH₃SO₃)₂ · 4 H₂O; Mn(CH₃SO₃)₂ · 2 H₂O; Cd(CH₃SO₃)₂ · 2 H₂O and Ag(CH₃SO₃). Their thermal behavior has been studied using TG and DTA, together with X-ray analysis of the solid products formed during the heating. The water of hydration is evolved in one step (Mn, Cd) or in two step (Cu, Zn). The intermediate hydrates and the anhydrous salts are crystallized. The anhydrous Zn, Ag and Cd compounds melt, the anhydrous Cd salt undergoing a polymorphic transition before melting. They then begin to decompose in the temperature range 325–440°C. Under an inert atmosphere, the decomposition yields well-crystallized residues of various composition: Cu + Cu₂S; Ag + Ag₂S (the sulfides being in very minute amounts); MnS; CdS; ZnO + ZnS.     

Glass formation in the systems Al2(SO4)3-MSO4-H2O (M = Cd2+, Zn2+, Mg2+) and Al2(SO4)3-Fe2(SO4)3-H2O

The glass formation region boundaries were found in the systems Al₂(SO₄)₃-MSO₄-H₂O, where M = Cd²⁺, Zn²⁺, and Mg²⁺, and Al₂(SO₄)₃-Fe₂(SO₄)₃-H₂O. The causes of the differences in glass-forming ability between the studied systems were analyzed. The structures and properties of glassy Al₂(SO₄)₃ · 11H₂O and Fe₂(SO₄)₃ · 11H₂O were compared.     

H3OLa(SO4)2 · 3 H2O: Ein neues saures Sulfat der Selten‐Erd‐Elemente

H₃OLa(SO₄)₂ · 3 H₂O: A New Acidic Sulfate of the Rare Earth Elements Colorless single crystals of H₃OLa(SO₄)₂ · 3 H₂O have been obtained by the reaction of La₂O₃ and sulfuric acid (80% H₂SO₄) at 150 °C. In the crystal structure (monoclinic, P2₁/c, Z = 4, a = 1119.5(5), b = 693.3(2), c = 1357.4(4) pm, β = 110.94(4)°) La³⁺ is ninefold coordinated by oxygen atoms which belong to five SO₄^– ions and three H₂O molecules. One of sulfate groups acts as a bidentate ligand. Hydrogen bonding is observed with H₂O molecules as donors and acceptors. Furthermore, strong hydrogen bonds are formed between the H₃O⁺ ions and oxygen atoms of the SO₄^2– groups.     

The luminescence of some lanthanide decatungstates

Luminescence of Na₉LnW₁₀O₃₆ · 18H₂O (Ln = Sm, Tb, Dy) and K₉EuW₁₀O₃₆ · 18H₂O is reported. Low efficiency of the Tb³⁺ compound is ascribed to non-radiative loss via a charge-transfer (Tb⁴⁺-W⁵⁺) state. The Sm³⁺ and Dy³⁺ compounds have only medium luminescence efficiency due to cross relaxation between lanthanide ions. The Eu³⁺ compound demonstrates again the sensitivity of Eu³⁺ luminescence to small changes.     

TG/DTA/MS Study of the thermal decomposition of FeSO4·6H2O

The thermal decomposition of FeSO₄·6H₂O was studied by mass spectroscopy coupled with DTA/TG thermal analysis under inert atmosphere. On the ground of TG measurements, the mechanism of decomposition of FeSO₄·6H₂O is: i) three dehydration steps FeSO₄·6H₂O FeSO₄·4H₂O+2H₂O FeSO₄·4H₂O FeSO₄·H₂O+3H₂O FeSO₄·H₂O FeSO4+H₂O ii) two decomposition steps 6FeSO₄ Fe₂(SO₄)₃+2Fe₂O₃+2SO₂ Fe₂(SO₄)3 Fe₂O₃+3SO₂+3/2O₂ The intermediate compound was identified as Fe₂(SO₄)₃ and the final product as the hematite Fe₂O₃.     

Syntheses,Structural Characterization,Reactivity, and Theoretical Studies on Some Heteroligand Oxoperoxotungstate(VI)

White microcrystalline diamagnetic oxoperoxotungstate(VI) complexes K[WO(O₂)₂F]·H₂O, K₂[WO(O₂)₂(CO₃)]·H₂O, [WO(O₂)(SO₄)(H₂O)₂] have been synthesized from reaction of Na₂WO₄·2H₂O with aqueous HF, solid KHCO₃, aqueous H₂SO₄ (W:F⁻ 1:3; W: CO₃ ^{2 −} 1:1; and W: SO₄ ^{2 −} 1:3), and an excess of 30% H₂O₂ at pH 7.5–8. Precipitation was completed by the addition of precooled acetone. The occurrence of terminal WO and triangular bidentate O₂ ^{2 −}(C _{2 v} ) in the synthesized compounds was ascertained from IR spectra. The IR spectra also suggested that the F⁻ and SO₄ ^{2 −} ions in K[WO(O₂)₂F]·H₂O and [WO(O₂)(SO₄)(H₂O)₂] were bonded to the WO ⁺⁴ center in monodentate manner, while CO₃ ^{2 −} ion in K₂[WO(O₂)₂(CO₃)]·H₂O binds the metal center in bidentate chelating fashion. The complex [WO(O₂)(SO₄)(H₂O)₂] is stable upto 110°C. The water molecule in [WO(O₂)(SO₄)(H₂O)₂] is coordinated to the WO ⁺⁴ center, whereas it occurs as water of crystallization in the corresponding peroxo(fluoro) and peroxo(carbonato) compounds. Mass spectra of the compounds are in good agreement with the molecular formulae of the complexes. K₂[WO(O₂)₂(CO₃)]·H₂O acts as an oxidant for bromide in the aqueous‐phase bromination of organic substrates to the corresponding bromo‐organics, and the complex also oxidizes Hantzsch‐1,4‐dihydropyridine to the corresponding pyridine derivative in excellent yield at room temperature. Density functional theory computation was carried out to compute the frequencies of relevant vibrational modes and electronic properties, and the results are in agreement with the experimentally obtained data.     

Physicochemical Analysis of the System Zr(SO<Subscript>4</Subscript>)<Subscript>2</Subscript>–Na<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>SO<Subscript>4</Subscript>–H<Subscript>2</Subscript>O at 25°С

The solubility in the quaternary water–salt system Zr(SO₄)₂ · 4Н₂О–Na₂SO₄–H₂SO₄–H₂O at 25°C was studied. It was found that, in the system, there is crystallization of not only Na₂SO₄ and Zr(SO₄)₄ · 4H₂O, but also sodium sulfate zirconates Na₂Zr(SO₄)₂(OH)₂ · 0.3H₂O, Na₄Zr(SO₄)₄ · 3H₂O, and Na₂Zr(SO₄)₂ · 3H₂O and two new compounds, S₁ and S₂, which are presumably Na₂ZrO(SO₄)₂ · 2H₂O and Na₂Zr₂O₂(SO₄)₃ · 6H₂O.     

Lanthanide Cluster Organic Frameworks Derived from Pyridine-2,6-dicarboxylate and Oxalate: Syntheses,Structures and Luminescence

Two novel cluster organic frameworks derived from pyridine-2,6-dicarboxylate (PDA) and oxalate (ox^2?) have been hydrothermally made: [Eu₃(SO₄)(PDA)₃(ox)_0.5(H₂O)₅]·4H₂O (1) and Er(PDA)(ox)_0.5(H₂O) (2). Compound 1 possesses one-dimensional chain structure constructed from the alternate linkage of tetranuclear [Eu₄(SO₄)₂]⁸⁺ (Eu₄) and dinuclear [Eu₂(ox)]⁴⁺ (Eu₂) clusters. Compound 2 is a two-dimensional layer based on dimeric [Er₂(COO)₂]²⁺ (Er₂) cluster units. Interestingly, such layer can be intuitively viewed as the linkages of helical chains and oxalate. In these two compounds, all anions are bivalent, and the ratio of trivalent lanthanide ions to these dianions is 2:3. Furthermore, compound 1 exhibits strong red luminescence upon 276 nm excitation.     

Coordination‐directed and Hydrogen‐bonded Assembly of Supramolecular Architectures Constructed from Diverse Coordination of Linear,Triangular, Tetragonal Pyramid,Trigonal Bipyramid,and Octahedral Mononuclear Units

Reaction of a imidazole phenol ligand 4‐(imidazlo‐1‐yl)phenol (L) with 3d metal salts afforded four complexes, namely, [Ni(L)₆] · (NO₃)₂ ( 1 ), [Cu(L)₄(H₂O)] · (NO₃)₂ · (H₂O)₅ ( 2 ), [Zn(L)₄(H₂O)] · (NO₃)₂ · (H₂O) ( 3 ), and [Ag₂(L)₄] · SO₄ ( 4 ). All complexes are composed of monomeric units with diverse coordination arrangements and corresponding anions. All the hydroxyl groups of monomeric cations are used as hydrogen‐bond donors to form O–H ··· O hydrogen bonds. However, the coordination habit of different metal ions produces various supramolecular structures. The Ni^II atom shows octahedral arrangement in 1 , featuring a 3D twofold inclined interpenetrated network through O–H ··· O hydrogen bond and π–π stacking interaction. The Cu^II atom of 2 displays square pyramidal environment. The O–H ··· O hydrogen bond from the [Cu(L)₄(H₂O)]²⁺ cation and lattice water molecule as well as π–π stacking produce one‐dimensional open channels. NO₃^– ions and lattice water molecules are located in the channels. 3 is a 3D supramolecular network, in which Zn^II has a trigonal bipyramid arrangement. Two different rings intertwined with each other are observed. The Ag^I in 4 has linear and triangular coordination arrangements. The mononuclear units are assembled into a 1D chain by hydrogen bonding interaction from coordination units and SO₄^2– anions.     

Influence of ethyl alcohol in the preparation, morphology and properties of compound DAS–Eu3+ and its thermal degradation products

In this study, two compounds presenting characteristics different from each other were produced from there action between hydrated Eu³⁺ sulfate and Ba²⁺ diphenylamine-4-sulfonate using, respectively, aqueous solution for producing the Eu(C₁₂H₁₀NSO₃)₃·7H₂O (A) compound and water/ethyl alcohol (7:1) solution for the Eu(C₁₂H₁₀NSO₃)₃·5H₂O (B) production. The presence of alcohol molecules in the solution will interfere in the structural arrangement of anionic surfactant DAS^? (diphenylamine-4-sulfonate) around the metal ions Eu³⁺ allowing differentiation in the stoichiometric formulas, morphology, and thermal properties of these compounds and their derivatives. Thus, when treating both compounds under oxidizing atmosphere, we found different temperatures of the water loss and conversion of the intermediate pair oxydisulfate [Eu₂O(SO₄)₂]/dioxysulfate [(Eu₂O₂SO₄)]. However, the effect of water/surfactant/alcohol interactions in the metal ion structural arrangement becomes still more evident under reducing atmosphere. After this thermal treatment, significant changes were observed in the morphological characteristics and physical properties of the (Eu₂O₂S oxysulfide) in compound B with respect to compound A.     

Darstellung und Eigenschaften von Na2CuII (SO4)2 · 6 H2O

Preparation and Properties of Na₂Cu^II (SO₄)₂ · 6 H₂O The preparation of the complex compound of Na₂Cu(SO₄)₂ · 6 H₂O is described. Its structure and properties were investigated using spectral methods (u.v.-vis., i.r., n.m.r.), by means of X-ray powder diffraction, and by thermal methods. On the basis of experimental results it is suggested that another member of the Tutton salts series has been prepared, appearring isostructural with them and showing the less distorted coordination polyhedron of [Cu(H₂O)₆]²⁺ from them. On its dehydration oxygen atoms from the sulphate groups enter the coordination sphere of Cu^II and the symmetry of SO₄^2? becomes lower. The experimental results indicate that Na₂Cu(SO₄)₂ · 6 H₂O as also Na₂Cu(SO₄)₂ as likewise Na₂Cu(SO₄)₂ · 2 H₂O are monoclinic.     

Tribochemistry and kinetics of Al2(SO4)3·xH2O decomposition

The thermal decomposition of tribochemically activated Al₂(SO₄)₃·xH₂O was studied by TG, DTA and EMF methods. For some of the intermediate solids, X-ray diffraction and IR-spectroscopy were applied to learn more about the reaction mechanism. Thermal and EMF studies confirmed that, even after mechanical activation of Al₂(SO₄)₃·xH₂O, Al₂O(SO₄)₂ is formed as an intermediate. Isothermal kinetic experiments demonstrated that the thermochemical sulphurization of inactivated Al₂(SO₄)₃·xH₂O has an activation energy of 102.2 kJ·mol^?1 in the temperature range 850–890 K. The activation energy for activated Al₂(SO₄)₃·xH₂O in the range 850–890 K is 55.0 kJ·mol^?1. The time of thermal decomposition is almost halved when Al₂(SO₄)₃·xH₂O is activated mechanically. The results permit conclusions concerning the efficiency of the tribochemical activation of Al₂(SO₄)₃·xH₂O and the chemical and kinetic mechanisms of the desulphurization process.     

Kinetics of thermal dehydration of Ce2(SO4)2, n(H,D)2O (n=5, 8, 9)

The thermal dehydration of Ce₂(SO₄)₃·5H₂O, Ce₂(SO₄)₃·8H₂O, Ce₂(SO₄)₃·9H₂O and their isomorphous deuterated compounds was studied by means of thermogravimetric measurements. A kinetic analysis of the TG curves obtained was carried out by computer. The thermal stability, Arrhenius parameters and mechanism of dehydration were investigated.     

Conductimetric and spectrophotometric investigation of lanthanide cyclohexaphosphates

The preparation and properties of some lanthanide cyclohexaphosphates Ln₂P₆O₁₈·nH₂O (Ln=La, Ce, Pr, Nd, Sm, Er and Yb) are described. Conductivity measurements and IR spectra are presented. The comparison with properties of some other salts, Nd (BrO₃)₃·9H₂O, NdP₃O₉·3H₂O and Nd₄ (P₄O₁₂)₃·13H₂O, suggests that the coordination number of Nd³⁺ in the cyclohexaphosphate is nine.     

Hemi(piperazinediium) hexaaqua­aluminium(III) bis­(sulfate) tetrahydrate: a new double aluminium sulfate salt

Piperazinium aluminium sulfate decahydrate, (C₄H₁₂N₂)_0.5[Al(H₂O)₆](SO₄)₂·4H₂O, exhibits a crystal structure built from isolated [Al(H₂O)₆]³⁺, SO₄²⁻, C₄H₁₂N₂²⁺ and H₂O units connected by a complex hydrogen‐bond network. The title compound shows strong similarities to many double alumin­ium sulfates, such as alums and Tutton's salts. However, since its structure is not derived directly from that of these compounds, it is assumed to be a new structure type.     

Synthesis, characterization and thermal analysis of 1:1 and 2:3 lanthanide(III) citrates

The synthesis and characterization of lanthanide(III) citrates with stoichiometries 1:1 and 2:3; [LnL·xH₂O] and [Ln₂(LH)₃·2H₂O], Ln=La, Ce, Pr, Nd, Sm and Eu are reported. L stands for (C₆O₇H₅)^3? and LH for (C₆O₇H₆)^2?. Infrared absorption spectra of both series evidence coordination of carboxylate groups through symmetric bridges or chelation. X-ray powder patterns show the amorphous character of [LnL·xH₂O]. The compounds [Ln₂LH₃·2H₂O] are crystalline and isomorphous. Emission spectra of Eu compounds suggest C _2v symmetry for the coordination polyhedron of [LnL·xH₂O] and C _4v for [Ln₂(LH)₃·2H₂O]. Thermal analyses (TG-DTG-DTA) were carried out for both series. The thermal analysis patterns of the two series are quite different and both fit in a 4-step model of thermal decomposition, with lanthanide oxides as final products.     

Vibrational spectra of NH4-Ln(SO4)2·4H2O/D2O (LnLa and Ce)

Infrared and Raman spectra of NH₄Ce(SO₄)₂·4H₂O, NH₄La(SO₄)₂·4H₂O and the deuterated compounds NH₄Ce(SO₄)₂·4D₂O and NH₄La(SO₄)₂·4D₂O have been analysed. Splittings indicating the presence of two types of SO₄ ions are not observed. The SO bond strengths of the different SO₄ units are not significantly different. The SO₄ ion is distorted in these compounds. Deuteration causes changes in the SO₄ bond strength. Three crystallographically distinct water molecules exist in the unit cell.     

Spectrophotometric and thermal analytical studies on the dehydration of copper(II) sulfate and its double salts

Spectrophotometric (diffuse reflection) and TG-DTA data on the dehydration of CuSO₄ · 5H₂O, Na₂Cu(SO₄)₂ · 2H₂O, M₂Cu(SO₄)₂ · 6H₂O(M⁺ = K⁺, Rb⁺, Cs⁺ and NH⁺₄) and Co₂Cu(SO₄)₃ · 18H₂O are given. Although complete dehydration of CuSO₄ · 5H₂O brings about a striking color change from blue to white, it was found that there is only a slight decrease in the v?_max. of its d-d band in the course of this change, and the total light absorption in the visible-UV region increases at the same time. The dehydration of the alkali metal and ammonium double salts, most of which contain [Cu(OH₂)₆]²⁺ aquo ions (in contrast to the [Cu(OH₂)₄]²⁺ in CuSO₄ · 5H₂O), occurs generally more easily than that of CuSO₄ - 5H₂O, and their v?_max. increases slightly in the change, leading to blue or green anhydrous products, although the formation of a white modification was observed with the potassium salt. It was also found that the v?_max. of the Cu²⁺ ion in the dehydrated cobalt(II) double salt is still lower than that in anhydrous CuSO₄, i.e., the ligand field and/or tetragonality around it is decreased by the presence of Co²⁺ ions.