Study of the state of uranogermanates MII(HGeUO6)2·6H2O in Aqueous Solutions (MII = Mn, Co, Ni, Cu, Zn)

The state of d-elements uranogermanates M^II(HGeUO₆)₂·6H₂O in aqueous salt solutions in a wide range of ionic strength, ionic composition, and acidity has been investigated. The pH ranges of the uranogermanates stability have been determined, and products of their transformation have been identified. Solubility, solubility equilibrium constant, and Gibbs energy of formation have been determined for the studied uranogermanates. Diagrams of uranium(VI), germanium(IV), and M(II) state in aqueous solutions and in equilibrium solid phases have been plotted.     

State of uranyl silicates MII(HSiUO6)2 ·6H2O (MII=Mn, Co, Ni, Cu, Zn) in aqueous solutions

Uranyl silicates with formula M^II(HSiUO₆)₂·6H₂O (M^II=Mn, Co, Ni, Cu, Zn) were investigated in aqueous solutions in the pH range of 0÷14. The pH interval was established where compounds preserve their composition and structure. It varies in the pH range of (3.5–4.0)÷(10.8–11.4) and depends on M^II type. Out of this pH interval investigated uranyl silicates convert to the compounds of other composition and structure, such as amorphous silica, polyuranates and hydroxides of 3d-transition elements. The solubility of M^II(HSiUO₆)₂·6H₂O was determined, it’s value changes on the several orders of magnitude from 10^?6 M in subalkali solutions to 10^?3 M in acid and strongly alkaline media. Using obtained experimental data the solubility products and solubility curves of uranyl silicates were calculated by mathematical modeling. Also the speciation diagrams of uranium (VI), silicon (IV) and M (II) in solutions and solids were plotted.     

Synthesis and characterization of MIIU3O10 · nH2O (MII = Mg, Mn, Co, Ni, Cu, Zn, Cd) triuranates

Individual crystalline phases of composition M^IIU₃O₁₀ · nH₂O were prepared by reacting schoepite UO₃ · 2.25H₂O with aqueous solutions of Mg, Mn, Co, Ni, Cu, Zn, or Cd nitrates under hydrothermal conditions at 200°C. The composition and structure of the resultant compounds were determined by hightemperature X-ray diffraction, IR spectroscopy, scanning calorimetry, and chemical analysis; the dehydration and thermal destruction of the compounds were studied.     

Coordination polymers of VIV—MII (MII = Mn,Co, Ni,Cd) with ethylmalonate anions

Russian Chemical Bulletin - A series of heterometallic 1D coordination polymers {[MII(VIVO)(Etmal)2(H2O)5] ? 2 H2O}n (MII = Mn (1), Co (2), Ni (3), Cd (4)) were synthesized. These compounds...     

Study of the state of uranoarsenates MII(AsUO6)2·nH2O(MII = Mn2+, Co2+, Ni2+, Cu2+, Zn2+, Cd2+, Pb2+) in aqueous solutions

State of uranoarsenates M^II(AsUO₆)₂·nH₂O (M^II = Mn, Co, Ni, Cu, Zn, Cd, Pb) in aqueous solutions in a wide range of acidity (pH 0?C14) was studied. Acid-base boundaries of existence of the compounds were estimated, products of conversion were identified, and solubility of M^II(AsUO₆)₂·nH₂O was determined. On the basis of the obtained data the solubility products and Gibbs functions of formation of uranoarsenates, and the solubility curves were calculated, phase diagrams of uranium(VI) and arsenic(V) in solutions and in equilibrium solid phases were constructed with the use of the equilibrium thermodynamics technique.     

XPS study of the electronic structure of heterometallic complexes [Fe2MO(O2CCH3)6(H2O)3] · 3H2O (M = Co,Ni)

Heterometallic compounds of general formula [Fe ₂ ^III M^IIO(O₂CR)₆(H₂O)₃] · 3H₂O (R = CH₃, M = Co, Ni; R = CCl₃, M = Co, Ni) have been studied by XPS. The compounds have been identified as high-spin complexes with metal atoms in oxidation states M(II) and M(III). Analysis of the XPS data revealed the tendency of the XPS pattern and magnetic parameters of molecules to change with a change in the electronic nature of metal atoms. The assignment is based on the degree of covalence of the M-O bond. In chloro-substituted heterocomplexes, electron density delocalization on the metal atoms with metal-to-ligand charge transfer through three bonds (M-O-C-C) is observed. The substitution in terminal groups leads to the change in the electron density distribution between the carboxylate and terminal groups.     

Comparison of the crystal structures of Co2(X 2O7)·2H2O,X=P and As

Summary Crystals of Co₂(X ₂O₇)·2H₂O,X=P/As were synthesized under hydrothermal conditions. Their crystal structures were determined by single crystal X-ray diffraction:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2)Å, =94.77(2)/94.74(2)°, space group P2₁/n,R=0.032/0.046,R _w=0.028/0.034 for 2423/2042 reflections and 131/119 variables. Within the twoXO₄ tetrahedra connected via a common corner to anX ₂O₇ group the average P-O bond lengths are approximately equal (1.540 and 1.543 Å), but As-O differs significantly (1.685 and 1.696 Å). A comparison with the isotypic Mn and Mg pyrophosphates shows a correlation between the ratio Me-O/X-O and the angle O-X-O.

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Vergleich der Kristallstrukturen von Co₂(X ₂O₇)·2H₂O,X=P und As

Zusammenfassung Kristalle von Co₂(X ₂O₇)·2H₂O,X=P/As wurden unter Hydrothermalbedingungen synthetisiert. Ihre Kristallstrukturen wurden mittels Röntgenbeugung an Einkristallen bestimmt:a=6.334(1)/6.531(2),b=13.997(2)/14.206(4),c=7.637(1)/7.615(2) Å, =94.77(2)/97.74(2)°, Raumgruppe P2₁/n,R=0.032/0.046,R _w=0.028/0.034 für 2423/2042 Reflexe und 131/119 Variable. In den beiden über eine gemeinsame Ecke zuX ₂O₇-Gruppen verknüpftenXO₄-Tetraedern sind die mittleren P-O-Abstände ungefähr gleich (1.540 und 1.543 Å), hingegen differiert As-O signifikant (1.685 und 1.696 Å). Ein Vergleich mit den isotypen Mn- und Mg-Pyrophosphaten zeigt eine Korrelation zwischen dem Quotienten Me-O/X-O und dem WinkelX-O-X.

     

Vibrational studies of metal-ethylenediamine thiosulfates—I. Infrared and Raman spectra of the tris-ethylenediamine thiosulfates MII(en)3S2O3(MII = Zn,Cd, Fe,Ni, Co,Mn) and some of their N-deuterated analogues

As a contribution to an extensive study of the vibrational behaviour of the thiosulfate ion in various compounds, i.r. and Raman spectra of solid isostructural tris-ethylenediamine thiosulfates, M^II(en)₃S₂O₃ (M^II = Zn, Cd, Fe, Ni, Co, Mn) and some of their N-deuterated derivatives, have been examined. In accordance with group theory expectations, the investigation of experimental methods, namely: (i) the vibrational behaviour of both pure compounds and isotopic species; (ii) a systematic comparison of the intensities and shapes of the i.r. bands and Raman peaks; (iii) the establishment of regular band shifts correlated to the nature of the central atom in the isostructural M^II(en)₃S₂O₃ compounds, leads to a consistent set of assignments of all the bands arising in the 100–4000 cm⁻¹ frequency region. Moreover, the investigation of isotopic species allows an easy discrimination between bands due to the vibration of the M(en)₃²⁺ entity and those arising from the S₂O₃²⁻ anion. Our data support the assumption that both ions retain their point group symmetry (D₃ for M(en)₃²⁺ and C_3v for S₂O₃²⁻) unaltered in the crystal lattice.     

Synthesis,spectral, thermal and structural characterization of {[Cu(H2O)3][Cu(MAL)2] · 2H2O}∞ and [Cu(MAL)(TEA)] · H2O (MAL = malonate and TEA = triethanolamine)

A polymeric malonato-bridged copper(II) complex, {[Cu(H₂O)₃][Cu(MAL)₂]· 2H₂O}, and a mononuclear malonato-copper(II) complex with triethanolamine, [Cu(MAL)(TEA)]·H₂O, have been prepared and characterized by elemental analyses, i.r., u.v.–vis, magnetic measurements and single crystal X-ray diffraction. The polymeric complex consists of one-dimensional chains containing the MAL bridged [Cu(H₂O)₃]²⁺ and [Cu(MAL)₂]^2– ions and each MAL ligand simultaneously exhibits chelating bidentate (at one copper atom) and bridging (at the adjacent copper atom) coordination modes. The intrachain Cu1...Cu2 separation is 4.963 Å and the polymeric complex exhibits antiferromagnetic behaviour. In the mononuclear complex, the copper(II) ion is octahedrally coordinated by one bidentate MAL and one tetradentate neutral TEA ligands. The i.r. spectra and thermal decompositions of both complexes are described.     

Bending modes of the water molecules and the MO stretching modes in the series MF2 · 4H2O (M = Fe,Co, Ni,Zn)

The infrared spectra of the series MF₂·4X₂O (M = Fe, Co, Ni, Zn; X = H, D) are reported in the frequency ranges of the bending vibrations of the water molecules (ν₂) at 296 and ∼100 K and the MO lattice vibrations (ν_MO) at 296 K. Four ν_MO vibrations consisting of two doublets are identified using deuterium substitution. The various ν_ZnO vibrations correlate well with the metal-oxygen distances R(ZnO), and this correlation is further used to calculate R(MO)'s of the remainder of the series and to refine R(ZnO). Four ν₂(H₂O, HDO, D₂O) vibrations, consisting of two sharp overlapping bands flanked by two broad shoulders, are identified. The number of ν₂(H₂O) components, the sequence of ν₂ in the series and the correlation with R(MO) suggest that the ν₂ frequencies are mainly determined by R(MO). Using this assignment the two types of ν₂ bands are assigned to the two types of crystallographically distinct water molecules found in the MF₂·4H₂O structure.     

MF2 vibrations and librations of water molecules in the series MF2·4H2O (M = Fe,Co, Ni or Zn)

The infrared absorption spectra of the series MF₂·4H₂O (M = Fe, Co, Ni or Zn) and of the respective deuterates were recorded at 296 and ∼ 100 K in the 1200-400 cm⁻¹ wavenumber region. Using the known ZnF₂·4H₂O structure as a model, the number of i.r. active librations and MF₂ vibrations was predicted with the aid of a group theoretical treatment. The librations were distinguished from the MF₂ and MO vibrations and assigned, using isotopic ratios and correlations between the unit cell volumes, the uncoupled OH and OD stretch vibrations of HDO and the twisting libration. The six librations are assigned to two types of water molecules with low symmetry and with different hydrogen bond strengths, and are compatible with an orthorhombic Pca2₁ structure. The v₁ and v₃ intramolecular MF₂ vibrations are assigned, using ZnF₂·4H₂O crystal data and matrix-isolated v₁ and v₃ (v_1.3) values as guide. Shifts of v_1.3 and v₁/v₃ relative to the matrix-isolated values suggest smaller MF bond lengths. The shifts in the values of v_1.3 and v₁/v₃ upon deuteration and lowering of the temperature indicate smaller MF bond lengths and FMF angles.     

Crystal structures and vibrational spectra ofMSnF6·6H2O(M=Fe,Co, Ni)

Summary Single crystal X-ray structural data (atT=300 K) are reported for CoSnF₆·6H₂O (rhombohedral; R{ie61-1}-C _3i ² ;a=9.735(7) Å,c=10.095(7) Å, =120°;Z=3;R=0.047) and for NiSnF₆· 6H₂O (rhombohedral; R{ie61-2}-C _3i ² ;a=9.697(1)Å,c=10.021(1)Å, =120°;Z=3;R=0.038). The two compounds are isostructural to FeSnF₆·6H₂O. IR and Raman spectroscopic data (atT=300 and 75 K) are reported for hydrated and for partially deuterated samples ofMSnF₆·6H₂O (M=Fe, Co, Ni). Two rather similar (OD) stretching frequencies and one (HDO) bending frequency of isotopically dilute HDO molecules are observed for either of the three compounds, which is consistent with one crystallographically distinct water molecule forming two different, but rather similar O ... F hydrogen bonds.

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Kristallstrukturen und Schwingungsspektren vonMSnF₆·6H₂O (M=Fe, Co, Ni)

Zusammenfassung Die Kristallstrukturen von CoSnF₆·6H₂O (rhomboedrisch; R{ie61-3}-C _3i ² ;a=9.735(7) Å,c=10.095(7) Å, =120°;Z=3;R=0.047) und von NiSnF₆·6H₂O (rhomboedrisch; R{ie61-4}-C _3i ² ;a=9.697(1)Å,c=10.021(1)Å, =120°;Z=3;R=0.038) wurden mittels Röntgen-Einkristalldaten (beiT=300 K) bestimmt. Die beiden Verbindungen sind isostrukturell zu FeSnF₆·6H₂O. IR- und Raman-Spektren vonMSnF₆·6H₂O (M=Fe, Co, Ni) wurden von Proben mit unterschiedlichem Deuterierungsgrad gemessen (beiT=300 und 75 K). Bei allen drei Verbindungen findet man für isotopenverdünnte HDO Moleküle zwei nur geringfügig unterschiedliche (OD)-Valenzfrequenzen und eine (HDO)-Deformationsfrequenz, was mit der Existenz von nur einer Art von Wassermolekülen mit zwei verschiedenen, aber doch sehr ähnlichen O ... F Wasserstoffbrückenbindungen übereinstimmt.

     

The conditions of formation of heterometallic complexes in the GeCl4 (SnCl4)-citric acid-M(CH3COO)2-H2O systems. The crystal and molecular structures of [M(H2O)6][Ge(HCit)2] · 4H2O (M = Mg, Mn, Co, Cu, Zn) and [M(H2O)6][Sn(HCit)2] · 4H2O (M = Mg, Co, Ni)

Fourteen bis(citrato)germanates(IV) and bis(citrato)stannates(IV) were prepared, in particular, [M(H₂O)₆][Ge(HCit)₂] · 4H₂O (M = Mg (I), Mn (II), Fe (III), Co (IV), Ni (V), Cu (VI), Zn (VII)) and [M(H₂O)₆][Sn(HCit)₂] · nH₂O (M = Mg, n = 4 (VIII); Mn, n = 2 (IX); Fe, n = 4 (X); Co, n = 4 (XI); Ni, n = 4 (XII); Cu, n = 4 (XIII); Zn, n = 3 (XIV)) (H₄Cit is citric acid). The purity and the composition of the products were determined by a set of physicochemical methods including elemental analysis, thermogravimetry, and IR spectroscopy. The structures of I, II, IV, VI, VII, VIII, XI, and XII were determined by X-ray diffractometry. All eight crystals composed of centrosymmetrical octahederal [M(H₂O)₆]²⁺ cations, [Ge(HCit)₂]^2? (or [Sn(HCit)₂]^2?) anions, and crystal water molecules are isostructural. The structural units in I, II, IV, VI, VII, VIII, XI, and XII are connected by systems of hydrogen bonds to form a three-dimensional framework.     

Phosphate ion vibrations in dihydrogen phosphate salts of the type M(H2PO4)2·2H2O (M = Mg,Mn, Co,Ni, Zn,Cd): Spectra–structure correlations

The infrared, far-infrared and Raman spectra of acid phosphate salts of the type M(H₂PO₄)₂·2H₂O (M = Mg, Mn, Co, Ni, Zn, Cd) in both protiated and deuterated forms have been recorded at ambient and liquid nitrogen temperature. The vibrational spectra have been interpreted with respect to the vibrations of the H₂PO₄⁻ ions. Strong vibrational couplings are established between the PO₄ stretching modes and POH bending modes as well as between the PO₄ bending modes and the water librations. The magnitude of the correlation field splittings A–B and g–u of the vibrational modes have been estimated. The influence of the metal ions on the frequencies of the stretching vibrations of the PO bonds has been discussed and some trends regarding the frequency variation within the M(H₂PO₄)₂·2H₂O series have been found. It has been established that the extent of the energetic distortions of H₂PO₄⁻ with respect to the PO bond lengths revealed by the spectroscopic data correlates with the extent of the geometric distortion shown by the structural data.     

Synthesis,Structure and Characterization of Three Metal Molybdate Hydrates: Fe(H2O)2(MoO4)2·H3O,NaCo2(MoO4)2(H3O2)and Mn2(MoO4)3·2H3O

Three metal molybdate hydrates,Fe(H2O)2(MoO4)2·H3O(FeMo),NaCo2(MoO4)2(H3O2)(CoMo)and Mn2(MoO4)3·2H3O(MnMo),were synthesized by the mixed-solvent-thermal methods and characterized by singlecrystal X-ray...     

Crystal structure of the coordination polymer [Cu2(S-mal)2(bpy)2(H2O)]·2.5H2O

Journal of Structural Chemistry - In the interaction of basic copper carbonate with optically pure malic acid and 4,4′-bipyridine [Cu2(S-mal)2(bpy)2(H2O)]·2.5H2O (1) is obtained. The...     

The magnetochemistry of novel cyano-bridged complexes Ln(DMF)4(H2O)2Mn(CN)6 · H2O (Ln = Tb,Dy, Er)

Using K₃Mn(CN)₆, DMF and Ln(NO₃)₃ · 6H₂O (Ln = Tb, Dy or Er), novel cyano-bridged complexes Ln(DMF)₄(H₂O)₂Mn(CN)₆ · H₂O (TbMn, DyMn and ErMn, respectively) were prepared and their magnetochemical properties were studied in detail. A weak antiferromagnetic interaction was found to exist between the rare earth ions and the manganese ion. Er(DMF)₄(H₂O)₂Mn(CN)₆ · H₂O, in particular, exhibits long-range magnetic ordering, a higher critical temperature (T _c = 17.5 K) and a stronger coercive force (H _c = 980 Oe).     

Single-molecule magnetism behavior of [Mn12O12(O2CR)16(H2O)4]2− salts

(PPh₄)₂[Mn₁₂O₁₂(O₂CCHCl₂)₁₆(H₂O)₄] (3) has been prepared by the two-electron reduction of [Mn₁₂O₁₂(O₂CCHCl₂)₁₆(H₂O)₄] (2) using iodide. Crystallization from CH₂Cl₂/hexanes yields a mixture of two crystal forms, 3·4CH₂Cl₂·H₂O (3a) and 36CH₂Cl₂ (3b), which are triclinic and monoclinic, respectively. They are both trapped valence 2Mn(II), 6Mn(III), 4Mn(IV). DC magnetization data for dried, unsolvated 3 in 1.80–4.00 K and 10–70 kG ranges were fit to give S=10, D=−0.28 cm⁻¹, g=2.00. Frequency-dependent out-of-phase (χ″_M) signals in AC susceptibility studies on crystalline sample of 3a and 3b combined with DC relaxation decay data were fit to the Arrhenius equation to give an effective energy barrier of U_eff=18.5 and 30.3 K, respectively. Magnetization vs. DC field sweeps on single crystals of 3a and 3b gave hysteresis loops containing steps due to quantum tunneling of magnetization (QTM). The step separations yielded ∣D∣/g values of 0.087 and 0.14 cm⁻¹, and consequently U=20 and 39 K (for g=2) for 3a and 3b, respectively, suggesting that the differences in U_eff are primarily caused by changes to D. This work demonstrates the sensitivity of the magnetic properties of [Mn₁₂]²⁻ single-molecule magnets to subtle differences in their environment.