A thermal study of some lanthanide trifluoromethyl sulfonates

Lanthanide trifluoromethyl sulfonates, M(SO₃CF₃)₃ · 9H₂O, have been prepared and characterized by analysis, optical properties and thermal behaviour. Dehydration proceeded in two steps for the lanthanum, cerium, praseodymium and neodymium salts and in three steps for other members of the lanthanide series. Thermal decomposition to lanthanide fluoride, carbonyl fluoride and sulfur dioxide occurred at temperatures greater than 400°C. This decomposition has been shown to be a two step process.     

Two- and Three-dimensional Frameworks with (6,3) and (10,3)-a Topology from Self-assembly of Three-connecting Organic Ligands with Cadmium(II) and Silver(I) Salts

Assembly of three-connecting ligands 1,3,5-tris(1-imidazolyl)benzene (tib) and 1,3,5-tris(imidazol-1-ylmethyl)-2,4,6-trimethylbenzene (titmb) with cadmium(II) and silver(I) salts provide new metal-organic frameworks, [Cd(tib)₂](NO₃)₂·4H₂O (1), [Ag(tib)(PPh₃)](CF₃SO₃) (2) and [Ag(titmb)(PPh₃)](CF₃SO₃)·1.5H₂O (3) (PPh₃=triphenylphosphine). Single-crystal X-ray diffraction studies reveal that complexes 1 and 3 are two-dimensional honeycomb networks, while complex 2 is a noninterpenetrated three-dimensional architecture with (10,3)-a topology. The results indicate that the nature (structure and flexibility) of the organic ligands and the bulky auxiliary ligand have great impact on the assembly and structure of metal-organic frameworks. The photoluminescent properties of the synthesized complexes were studied in the solid state at room temperature.     

Thermal decomposition processes of lanthanide trifluoroacetates trihydrates

The thermal decomposition of several lanthanide salts Ln(CF₃COO)₃·3H₂O (Ln=La, Gd, Tb) was studied under quasi-equilibrium conditions and under linear heating. According to mass spectral data, H₂O is the single product of thermal decomposition up to 120-140°C. Thermogravimetric data were processed with 'Netzsch Thermokinetics' computer program. Kinetics parameters of the first decomposition step (as the simple dehydration process, not complicated by the water hydrolysis with the liberation or the decomposition of the organic ligand) were calculated. This revised version was published online in July 2006 with corrections to the Cover Date.     

SYNTHESIS AND PROPERTIES OF ADDITION COMPOUNDS BETWEEN TRIPHENYLPHOSPHINE-OXIDE(TPPO) AND LANTHANIDE TRIFLUOROMETHANESULFONATES

Abstract

Additon compounds between triphenylphosphine-oxide and trifluoromethanesulfonates are synthesized and characterized by microanalyses, electrolytic conductance, vibrational (infrared) spectra, absorption spectra in the visible region and thermogravimetric procedures. The results are in agreement with the formulas La(CF₃SO₃)₃ 3TPPO 4H₂O and Ln(CF₃SO₃)₃·4TPPO. The ligands (TPPO) coordinate through the phosphoryl oxygen. Complex interactions with solvents of different donating capacities are also found. Thermogravimetric studies result in lanthanide trifluoride products.     

Variable temperature PXRD investigation of the phase changes during the dehydration of potassium Tutton salts

The thermal dehydration of the potassium Tutton salts K₂M(SO₄)₂·6H₂O (M = Mg, Co, Ni, Cu, Zn) was investigated using thermal gravimetric analysis (TG), differential scanning calorimetry (DSC), FTIR, and variable temperature powder X-ray diffraction. While each Tutton salts lost all six waters of hydration when heated to 500 K, the decomposition pathway depended on the divalent metal cation. K₂Ni(SO₄)₂·6H₂O lost all six waters in a single step, and K₂Cu(SO₄)₂·6H₂O consistently lost water in two steps in capped and uncapped cells. In contrast, multiple decomposition pathways were observed for the magnesium, cobalt, and zinc Tutton salts when capped and uncapped TG cells were used. K₂Zn(SO₄)₂·6H₂O lost the waters of hydration in a single step in an uncapped cell and in two steps in a capped cell. Both K₂Mg(SO₄)₂·6H₂O and K₂Co(SO₄)₂·6H₂O decomposed in a series of steps where the stability of the intermediates depended on the cell configuration. A greater number of phases were often observed in DSC and capped-cells TG experiments. A quasi-equilibrium model is presented that could explain this observation. These results highlight that experimental conditions play a critical role in the observed thermal decomposition pathway of Tutton salts.     

Reactions of heavier lanthanides with hydrazine in the presence of sulphur dioxide

Hydrazine hydrate reacts with sulphur dioxide in aqueous solution in the presence of heavier lanthanide(III) ions to give variety of complexes. The nature of product formed is highly pH dependent. Several hydrazine complexes of Ln(III) ions of the compositions Ln(N₂H₃SOO)₃(H₂O), Ln₂(SO₃)₃·2N₂H₄ and N₂H₅Ln(SO₃)₂(H₂O)₂ where Ln = Eu, Gd, Tb or Dy and the precursors for the hydrazinium lanthanide sulphite hydrates, the anhydrous lanthanide hydrazinecarboxylates, Ln(N₂H₃COO)₃ where Ln = Eu, Gd, Tb or Dy have been prepared and characterized by analytical, spectral, thermal and X-ray powder diffraction techniques. The infrared spectral data are in favour of the coordination of hydrazine and water molecules. These complexes decompose in three stages to yield respective oxides as final residue. The final residues were confirmed by their X-ray powder diffraction patterns and TG mass losses. The SEM photographs of some of the oxides show a lot of cracks indicating that large quantity of gases evolved during decomposition.     

Chair‐ and Boat‐Configurations of Silver(I) Complexes of Ditopic Ligand Involving Benzimidazolyl Substituents

The ditopic ligand 1, 2‐bis(benzimidazol‐1‐ylmethyl)benzene (L¹) as well as its silver(I) complexes [Ag₂L¹₂(CF₃CO₂)₂] ( 1 ) and [Ag₂L¹₂](CF₃SO₃)₂ · (L¹) · 2H₂O · 0.5C₂H₅OH ( 2 ) were prepared and structures characterized by X‐ray crystallography. The Ag^I atoms in 1 are trigonally coordinated by two N_BIm atoms from the arms of L¹ and by one O atom of the anion CF₃CO₂^—, while those in 2 are only linearly ligated by N_BIm. Different silver salts of CF₃CO₂^— and CF₃SO₃^— lead to different configurations of the dimeric unit [Ag₂L¹₂]²⁺: chair‐form in ( 1 ) but boat‐form in ( 2 ). The discrete molecules in both 1 and 2 are assembled into network structures through face‐to‐face π · · · π stacking and edge‐to‐face C—H · · · π interactions in the crystalline state, as well as N—H · · · O and C—H · · · O hydrogen bonds. Solution ¹H NMR studies showed the formation of one sole species in solution or a rapid equilibrium was established on the NMR time scale at room temperature.     

Anion Effect on Structure of Silver(I) Complexes with New Unsymmetrical Tripodal Ligand

Reactions of new unsymmetrical pyridyl‐ and imidazoyl‐containing tripodal ligand, 3‐(1H‐imidazol‐1‐yl)‐N,N‐bis(2‐pyridylmethyl)propan‐1‐amine ( L ), with varied silver(I) salts result in formation of three supramolecular architectures [Ag₂L₂](BF₄)₂·H₂O ( 1 ), [Ag₂L₂](ClO₄)₂·H₂O ( 2 ) and [Ag₃L₂](CF₃SO₃)₃ ( 3 ). All the structures were established by single‐crystal X‐ray diffraction analysis. In the solid state, three complexes consist of one‐dimensional infinite chains, in which the conformation and the bridging mode of L for complexes 1 and 2 are the same but 3 different. There are Ag···Ag and π‐π interactions in 3 . The results imply that the shape and size of the anion have great impact on the structure of the complexes. The complexes were also characterized by electrospray mass spectrometry.     

Research of thermal decomposition of hydrated methanesulfonates

Hydrated methanesulfonates Ln(CH₃SO₃)₃·nH₂O (Ln=La, Ce, Pr, Nd and Yb) and Zn(CH₃SO₃)₂·nH₂O were synthesized. The effect of atmosphere on thermal decomposition products of these methanesulfonates was investigated. Thermal decomposition products in air atmosphere of these compounds were characterized by infrared spectrometry, the content of metallic ion in thermal decomposition products were determined by complexometric titration. The results show that the thermal decomposition atmosphere has evident effect on decomposition products of hydrated La(III), Pr(III) and Nd(III) methanesulfonates, and no effect on that of hydrated Ce(III), Yb(III) and Zn(II) methanesulfonates. This revised version was published online in August 2006 with corrections to the Cover Date.     

Platinum complexes bearing 2,2′-dipyridylamine ligand

The replacement of the iodide ligands in the complex [PtI₂(dpa)] (1) (dpa is 2,2′-dipyridylamine) by silver triflate in acetonitrile afforded the compound [Pt(dpa)(MeCN)₂](SO₃CF₃)₂ (2). Homoleptic complexes [Pt(dpa)₂](X)₂ (3·(X)₂) were synthesized by the treatment of [PtI₂(dpa)] (1) with 2,2′-dipyridylamine in the presence of silver salts AgX in methanol (X = NO₃) or acetonitrile (X = SO₃CF₃). The deprotonation of the complex [3](SO₃CF₃)₂ to give the homoleptic complex [Pt(dpa-H)₂] (4) was performed by two methods, e.g., by the treatment of [3](SO₃CF₃)₂ with 2 equiv. of NaOH in methanol or by the addition of excess Et₃N to a suspension of [3](SO₃CF₃)₂ in methanol. The structures of compounds 1–4 were established by elemental analyses, high resolution electrospray ionization mass spectrometry, IR and NMR spectroscopy; the crystal structure of complexes [2](SO₃CF₃)₂, [3](NO₃)₂·H₂O, [3](SO₃CF₃)₂·2H₂O, and 4 were determined by single-crystal X-ray diffraction.     

Magnetostructural examination of Mn(III) complexes [Mn(cyclam)X2]+ with strong axial ligands

Three novel Mn(III) cyclam complexes, [Mn(cyclam)(NCBH₃)₂](CF₃SO₃), [Mn(cyclam)(NCBPh₃)₂](CF₃SO₃), and [Mn(cyclam)(NCSe)₂](CF₃SO₃) · H₂O, have been synthesized. These complexes are in the high-spin state between 4 and 350 K, and show large zero-field splittings. The crystal structure of [Mn(cyclam)(NCBH₃)₂](CF₃SO₃) was determined where the axial elongation of Mn–N bonds is found to be the largest among the homologue complexes. Ligand field in the [Mn(cyclam)X₂]⁺ complex series was examined by angular-overlap model calculation.     

Double sulphates of plutonium(III) and lanthanides with sodium

Sodium plutonium double sulphate monohydrate, NaPu(SO₄)₂ · H₂O and its lanthanide isomorphs NaLn(SO₄)₂ · H₂O (Ln ≡ Y, La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm and Yb) were synthesized and characterised by chemical and X-ray diffraction methods. All these compounds belonged to the same structural family where the Pu³⁺ or Ln³⁺ ion is coordinated to nine oxygen atoms. The structure of NaPu(SO₄)₂ · H₂O was found in the present work to be isomorphous with NaCe(SO₄)₂ · H₂O reported in the literature. The unit cells of all the lanthanide compounds showed regular contraction with atomic number.     

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.     

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.     

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.     

IR spectra and thermal decomposition/dehydration of double complex salts of lanthanum(III) sulphate complex anions with several cobalt(III) ammine complex cations

Double complex salts of lanthanum(III) sulphate complex anions with several cobalt(III) ammine complex cations, [Co(NH₃)₆][La(SO₄)₃]·H₂O (1), (NH₄)₃[Co(NH₃)₅ H₂O]-[La(SO₄)₃]₂·2H₂O (2), and (NH₄)₃[Co(NH₃)₄(H₂O)₂][La(SO₄)₃]₂·2H₂O (3), were prepared by the addition of hexaamminecobalt(III), pentaammineaquacobalt(III), and cis- tetra-amminediaquacobalt(III) complexes to the solution containing lanthanum(III) ion and excess ammonium sulphate. The IR spectra of sulphate groups of these double complex salts were much more complicated than those of the almost free sulphate groups such as (NH₄)₂SO₄ and [Co(NH₃)₆]₂(SO₄)₃·5H₂O. Furthermore, values of activation energy in the dehydration process of 1, 2 and 3 were estimated using modified Doyle's and Wiedemann's method. They were 95.6 ± 4.3, 157.1 ± 15.5 and 163.2 ± 20.8 kJ mol^?1, respectively. Here, one molecule water is released per molecule of 1, 2 and 3.     

Insights into crystal structures,supramolecular architectures and antioxidant activities of self-assembled fluorescent hetero-multinuclear [Cu (II)-Ln (III)] (Ln = La,Ce, Pr and Nd) salamo-like complexes

Newly designed hetero-dinuclear 3d–4f complex [Cu(L)La (NO₃)₂(μ-NO₃)(H₂O)]·EtOH ( 1 ), hetero-tetranuclear 3d–4f complex [Cu(L)Ce (NO₃)₂(μ-NO₃)(OAc)₂]₂·MeOH ( 2 ) and hetero-multinuclear 3d–4f complexes [{Cu(L)Ln (NO₃)₃}₂][Cu(L)Ln (NO₃)₃]₂ (Ln = Pr ( 3 ) and Nd = ( 4 )) have been self-assembled from the reaction of Cu (OAc)₂·H₂O, Ln (NO₃)₃·6H₂O (Ln = La, Ce, Pr and Nd) with an unsymmetric salamo-like bisoxime ligand H₂L (6-Methoxy-6′-ethoxy-2,2′-[ethylenedioxybis (nitrilomethylidyne)]diphenol) based on a Schiff base condensation of 2-[O-(1-ethoxyamide)]oxime-6-methoxyphenol and 3-ethoxysalicylaldehyde. The structures of complexes 1 – 4 were characterized by elemental analyses, PXRD analyses, IR, UV–Vis spectra, and single-crystal X-ray analyses. In addition, the supramolecular interactions and fluorescence properties of complexes 1 – 4 are discussed in detail. Moreover, the antioxidant activities of the complexes 1 – 4 were determined by superoxide radical-scavenging method in vitro, which indicates that the complexes 1 – 4 all show potential antioxidant properties.     

Thermal decomposition of Cu(II) complexes with salicylaldehyde S-methyl thiosemicarbazone

The thermal decomposition of copper(II) complexes with salicylaldehyde S-methylthiosemicarbazone of general formula Cu(HL)X·nH₂O (X=Py+NO₃, NCS, 0.5SO₄) and [Cu(L)NH₃]·H₂O was investigated in air atmosphere in the interval from room temperature to 1000°C. Decomposition of the complexes occurred in several successive endothermic and exothermic processes, and the residue was in all cases CuO.     

The syntheses and magnetic properties of a series of heterospin [LnIIICuII 4] pentanuclear complexes

Twelve oxamide-bridged Ln(III)–Cu(II) heteropentanuclear complexes Ln[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (Ln = La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Yb, and PMoxd = the N,N′-Bi(α-pyridylmethyl)-oxamide dianion) and 12 oxamide-bridged Ln(III)–Cu(II) heteropentanuclear complexes with the formula of Ln[Cu(PEoxd)]₄(ClO₄)₃ · 5H₂O (PEoxd = the N,N′-Bi(α-pyridylethyl)-oxamide dianion) were synthesized and characterized. The magnetic properties of Gd[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (7) and Gd[Cu(PEoxd)]₄(ClO₄)₃ · 2H₂O (19) show that there are ferromagnetic interactions between Gd(III) and Cu(II) in the complexes with J _Cu–Gd = 1.38 cm^?1 and J _Cu–Gd = 1.00 cm^?1, respectively. Fluorescent quenching phenomena for Eu[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (6) and Tb[Cu(PMoxd)]₄(ClO₄)₃ · 5H₂O (8) were also observed.     

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.