Synthesis and Structure of [Pd(NH3)4][cis-Pd(NH3)2(SO3)2][Pd(NH3)3(SO3)] · H2O

A new palladium compound [Pd(NH₃)₄][cis-Pd(NH₃)₂(SO₃)₂][Pd(NH₃)₃(SO₃)] · H₂O (I) was synthesized and its structure was studied by X-ray powder diffraction method. In the course of the synthesis, the initial trans-diamminesulfite anionic complex is transformed into the cis-configuration. Further heating in aqueous solution results in isomerization of a substance into a neutral complex [Pd(NH₃)₃(SO₃)]. Crystals I are triclinic: a = 10.3297(2) Å, b = 14.1062(3) Å, c = 6.8531(1) Å, = 101.36(0)°, = 92.74(0)°, = 92.71(0)°, space group P1¯. Structure I consists of the columns with alternating cis-[Pd(NH₃)₂(SO₃)₂]^2– and [Pd(NH₃)₃(SO₃)] complexes and [Pd(NH₃)₄]²⁺ ions between the columns.     

Structure of [NH3(CH2)4NH3]2P4O12·2H2O

After a short survey of what is the present state of the cyclophosphates associated with the organic molecule NH₂(CH₂)₄NH₂, we report chemical preparation and crystal structure for a new example of such compounds. [NH₃(CH₂)₄NH₃]₂P₄O₁₂.2H₂O is monoclinic (S.G. : P2₁/n), with Z = 2 and the following unit-cell parameters : a = 7.6728(8) Å, b = 18.962(3) Å, c = 7.9789(9) Å β = 111.751(9)°. Bidimensional layer arrangement of P₄O₁₂ rings connected to the water molecules thanks to weak H-bonds run parallel to the ab plane. The organic groupements located between these inorganic planes perform the three-dimensional cohesion by NH····O hydrogen bonds.     

Syntheses and structures of nine-coordinate NH4[HoIII(Edta)(H2O)3] · 1.5H2O, (NH4)4[Ho 2 III (Dtpa)2] · 9H2O, and (NH4)3[HoIII(Ttha)] · 5H2O complexes

The three title complexes, NH₄[Ho^III(Edta)(H₂O)₃] · 1.5H₂O (I) (H₄Edta = ethylenedianine-N,N,N′,N′-tetraacetic acid), (NH₄)₄[Ho ₂ ^III (Dtpa)₂] · 9H₂O (II) (H₅Dtpa = diethylenetriamine-N,N,N′,N″,N″-entaacetic acid), and (NH₄)₃[Ho^III(Ttha)] · 5H₂O (III) (H₆ Ttha = triethylenetetramine-N,N,N′,N″,N?,N?-hexaacetic acid), have been prepared and characterized by FT-IR, elemental analyses, and single-crystal X-ray diffraction technique. Complex I has a nine-coordinate mononuclear structure with distorted monocapped square antiprismatic conformation and its crystal structure belongs to orthorhombic system and Fdd2 space group. The crystal data are as follows: a = 19.343(9), b = 35.125(17), c = 12.364(6) Å, V = 8400(7) ų, Z = 16, M = 552.26, ρ_calcd = 1.747 g cm^?3 μ = 3.828 mm^?1, and F(000) = 4368. Complex II has a binuclear nine-coordinate pseudomonocapped square antiprismatic conformation and its crystal structure belongs to triclinic system and space P1 group. The crystal data are as follows: a = 9.7637(16), b = 9.9722(16), c = 12.945(2) Å, α= 85.853(2)°, β = 77. 140(2)°, γ = 77.140(2)°, V = 1198.4(3) ų, Z = 1, M = 1340.80, ρ_calcd = 1.858 g cm^?3, μ = 3.380 mm^?1, and F(000) = 674. As for complex III, it also has nine-coordinate mononuclear structure with distorted tricapped trigonal prism and its crystal structure belongs to monoclinic system andP2₁/c space group. The crystal data are as follows: a = 10.349(3), b = 12.760(4), c = 23.142(7) Å, β = 91.020(6)°, V = 3055.6(16) ų, Z = 2, M = 797.55, ρ_calcd = 1.734 g cm^?3, μ = 2.674 mm^?1, and F(000) = 1624. The results showed that although the ligands are different from one another in the shape and the numbers of coordination atoms, they all have nine-coordinate structures. However, one of them has binuclear structure and the other two have mononuclear structures because of the difference of the ligands.     

A theoretical study of the H2SO4+H2O → HSO4 −+H3O+ reaction at the surface of aqueous aerosols

The surface region of sulfate aerosols (supercooled aqueous concentrated sulfuric acid solutions) is the likely site of a number of important heterogeneous reactions in various locations in the atmosphere, but the surface region ionic composition is not known. As a first step in exploring this issue, the first acid ionization reaction for sulfuric acid, H₂SO₄ + H₂O HSO₄^– + H₃O⁺, is studied via electronic structure calculations at the Hartree–Fock level on an H₂SO₄ molecule embedded in the surface region of a cluster containing 33 water molecules. An initial H₂SO₄ configuration is selected which could produce H₃O⁺ readily available for heterogeneous reactions, but which involves reduced solvation and is consistent with no dangling OH bonds for H₂SO₄. It is found that at 0 K and with zero-point energy included, the proton transfer is endothermic by 3.4 kcal/mol. This result is discussed in the context of reactions on sulfate aerosol surfaces and, further, more complex calculations.Contribution to the Jacopo Tomasi Honorary Issue     

Theoretical studies of the g factors and local structures of the Ni3+ centers in Na2Zn(SO4)2·4H2O and K2Zn(SO4)2·6H2O crystals

The local structures and the g factors g_i (i = x, y, z) for Ni³⁺ centers in Na₂Zn(SO₄)₂·4H₂O (DPPH) and K₂Zn(SO₄)₂·6H₂O (PHZS) crystals are theoretically studied by using the perturbation formulas of the g factors for a 3d⁷ ion with low spin (S = 1/2) in orthorhombically compressed octahedra. In these formulas, the contributions to g factors from both the spin-orbit coupling interactions of the central ion and ligands are taken into account, and the required crystal-field parameters are estimated from the superposition model and the local geometry of the systems. Based on the calculations, the Ni-O bonds are found to suffer the axial compression δz (or Δz) of about 0.111 Å (or 0.036 Å) along the z-axis for Ni³⁺ centers in DPPH (or PHZS) crystals. Meanwhile, the Ni-O bonds may experience additional planar bond length variation δx (≈0.015 Å) along x- and y-axes for the orthorhombic Ni³⁺ center in DPPH. The theoretical g factors agree well with the experimental data. The obtained local structural parameters for both Ni³⁺ centers are discussed.     

Phase Equilibria in the System NH4Al(SO4)2–H2SO4–H2O

Equilibrium solubility curves of the ammonium aluminium sulphate in aqueous solutions of sulphuric acid have been calculated using checked literature data and our own measurements. The concentration of sulphuric acid ranged from 0 to 23 mass%, temperature range between 20 and 60°C has been extrapolated up to 75°C by means of a thermodynamically based correlation method. The solubility correlation as well as the hydration analysis implied a possible destructuralization of solutions at higher acid concentrations. This revised version was published online in August 2006 with corrections to the Cover Date.     

A theoretical investigation on optimal structures of ethane clusters (C2H6)n with n ≤ 25 and their building-up principle

Geometry optimization of ethane clusters (C(2)H(6))(n) in the range of n ≤ 25 is carried out with a Morse potential. A heuristic method based on perturbations of geometries is used to locate global minima of the clusters. The following perturbations are carried out: (1) the molecule or group with the highest energy is moved to the interior of a cluster, (2) it is moved to stable positions on the surface of a cluster, and (3) orientations of one and two molecules are randomly modified. The geometry obtained after each perturbation is optimized by a quasi-Newton method. The global minimum of the dimer is consistent with that previously reported. The putative global minima of the clusters with 3 ≤ n ≤ 25 are first proposed and their building-up principle is discussed.     

Synthesis,crystal structure of Gd(H2O)(C2O4)2 · NH4 and of La(C2O4)2 · NH4. Characterization of the Ln(H2O)(C2O4)2 · NH4 with Ln=Eu…Yb

Single crystals of two lanthanide complexes, presenting similar formula Ln(H₂O)_x(C₂O₄)₂ · NH₄ with Ln=La, x=0 and Ln=Gd, x=1, have been prepared, in closed system at 200 °C. The gadolinium complex is bi-dimensional. A layer is built by the packing of the basic unit, [Gd(C₂O₄)]₄. The gadolinium atoms are related only by bischelating oxalate ligands, the ammonium ion and the water molecule (bound to the gadolinium atom) are localized into the interlayer space. The lanthanum complex is tri-dimensional. The basic building unit remains approximately the same and the packing of these units form a layer. However, within these units, the lanthanum atoms are related by either an oxalate ligand or an edge. Moreover, an oxalate ligand assumes the connection between the layers. The ammonium ion is localized into two sets of intersecting channels. Pure phase of the gadolinium complex has been prepared at 100 °C and extended to some lanthanide elements, Eu…Yb. As the size of the lanthanide ionic radius is decreasing, it is noticeable that the a unit–cell constant follows an expansion pattern while the others two follow an usual contraction one. The thermal behavior of this family shows that the anhydrous compounds are obtained and that some water molecule is sorbed during the cooling. Thus, the anhydrous compounds present a relatively open-framework with some small micropores.     

Solubility and stability of (NH4)2SO4 · H2O2 in aqueous solutions and change in some crystallographic parameters of (NH4)2SO4 precipitates

Stability of (NH₄)₂SO₄ · H₂O₂ aqueous solutions and some structural changes in ammonium sulfate in the course of its solvation and subsequent desolvation were studied.     

Thermochemical investigations of the systems KCl−KBr−H2O,K2SO4−(NH4)2SO4−H2O and KNO3−NH4NO3−H2O at 298.15 K

For the equilibrium solid phases occurring in the systems: KCl?KBr?H₂O, K₂SO₄?(NH₄)₂SO₄?H₂O and KNO₃?NH₄NO₃?H₂O, the concentration dependencies of differential solution enthalpies, Δ_sol H ₂ for several crystallization paths, were measured. The limiting differential solution enthalpies, Δ_sol H ₂ ⁰ , were determined by extrapolation of the above dependencies to the ionic strength,I _m ⁰ , corresponding to the appropriate binary solutions. For KCl?KBr?H₂O system only, the clear dependence between Δ_sol H ₂ ⁰ andI _m ⁰ values was found and discussed.     

Influence of MgHPO4·3H2O and Mg3(PO4)2·8H2O on Thermal Reactions (20°-1000°C) in Solid Solutions with Al2(SO4)3·16H2O

Abstract

The following binary systems were studied: AI₂(SO₄)₃·16H₂0 - MgHPO₄·3H₂O and AI₂(SO₄)₃·16H₂O - Mg₃(P0₄)₂·8H₂0.     

Structure of (C3H5NH3)2H2P2O7·H2O

The bis(cyclopropylammonium)dihydrogenodiphosphate monohydrate is a new diphosphate associated with the organic molecule C₃H₅NH₂. We report the chemical preparation and the crystal structure of this organic cation diphosphate. (C₃H₅NH₃)₂H₂P₂O₇.H₂O is orthorhombic (S.G. : P2₁2₁2₁), with Z = 4 and the following unit-cell parameters : a = 4.828(1) Å, b = 11.011(1) Å, c = 25.645(2) Å. The P₂O₇ groups and H₂O water molecules form a succession of bidimensional layers perpendicular to the c axis. The organic cations ensure the three-dimensional cohesion by NH-O hydrogen bonds.     

A Novel Copper Ammonium Diphosphate--Dimorphic Cu 3 (NH 4 ) 2 (P 2 O 7 ) 2 ·3H 2 O

This article deals with the insoluble compounds, formed in CuSO 4 -(NH 4 ) 4 P 2 O 7 -H 2 O system. The solutions were analyzed by means of chemical analysis, the precipitate--by means of x-ray diffraction, chemical and thermal analysis, and FTIR spectroscopy. We have established that at least three poorly soluble compounds can form in the system CuSO 4 -(NH 4 ) 4 P 2 O 7 -H 2 O. Their chemical formulae are Cu 2 P 2 O 7 ;5H 2 O and polymorphic Cu 3 (NH 4 ) 2 (P 2 O 7 ) 2 ;3H 2 O. The first modification is most stable when |Cu + P 2 O 7 | = 0.25 M ( n = 1.0), and, in a matter of days, Dimorph A transforms to Dimorph B, which has not been described in any publications.     

A Raman spectroscopic study of the mineral coquandite Sb6O8(SO4)·(H2O)

Raman spectra of coquandite Sb₆O₈(SO₄)·(H₂O) were studied, and related to the structure of the mineral. Raman bands observed at 970, 990 and 1007 cm^?1 and a series of overlapping bands are observed at 1072, 1100, 1151 and 1217 cm^?1 are assigned to the SO₄^2? ν₁ symmetric and ν₃ antisymmetric stretching modes respectively. Raman bands at 629, 638, 690, 751 and 787 cm^?1 are attributed to the SbO stretching vibrations. Raman bands at 600 and 610 cm^?1 and at 429 and 459 cm^?1 are assigned to the SO₄^2? ν₄ and ν₂ bending modes. Raman bands at 359 and 375 cm^?1 are assigned to O–Sb–O bending modes. Multiple Raman bands for both SO₄^2? and SbO stretching vibrations support the concept of the non-equivalence of these units in the coquandite structure.     

A cobalt molybdenum phosphate with a tunnel: Hydrothermal synthesisand structure of (NH3CH2CH2NH3)4·(NH3CH2CH2NH2)·Na·[Co2Mo12O30(PO4)(HPO4)4(H2PO4)3]·5H2O

Transition Metal Chemistry -     

Polarized Raman study of the Ce2(SO4)3·9(H,D)2O

The Raman spectra of oriented single crystals of cerium sulfate enneahydrate and that of its fully deuterated analogue are reported and compared. The role of the two types of lattice water molecules have been determined from the geometries of their immediate environments and consequent vibrational properties. The data obtained are subjected to certain geometric criteria to determine the orientations of the H₂O(C₁) and H₂O(C_s) molecules consistent with optimum interactions with their surroundings.     

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.     

Syntheses and Structural Researches of Nine-Coordinated (NH4)[EuIII(Edta)(H2O)3] · H2O and (NH4)3[EuIII(Ttha)] · 5H2O1

The crystal and molecular structures of the (NH₄)[Eu^III(Edta)(H₂O)₃] · H₂O (I); Edta^4– is an ethylenediaminetetraacetate anion) and (NH₄)₃[Eu^III(Ttha)] · 5H₂O (II); Ttha^6– is a triethylenetetraminehexaacetate anion) complexes have been determined by single-crystal X-ray structure analysis. The crystal of complex I is orthorhombic with Fdd2 space group. The crystal data are as follows: a = 1.9505(8) nm, b = 3.5445(14) nm, c = 1.2442(5) nm, V = 8.602(6) nm³, Z = 16, M = 531.29, p = 1.579 g cm^–3, = 2.970 mm^–1, and F(OOO) = 3924. The final R and wR values are 0.0378 and 0.1030 for 2799 (I > 2.0(I)) unique reflections, and 0.0495 and 0.1072 for all 6237 reflections, respectively. The nine-coordinated [Eu^III(Edta)(H₂O)₃]^– complex anion has a pseudo-monocapped square antiprismatic structure in which the nine coordinated atoms, two N and four O are from one Edta ligand and three O atoms from water molecules. The crystal of complex II is monoclinic with P2₁/c space group. The crystal data are as follows: a = 1.0387(3) nm, b = 1.2737(4) nm, c = 2.3031(7) nm, = 90.870(5)°, V = 3.047(2) nm³, Z = 4, M = 784.58, C 51.83, H 4.32, N 115.12. = 1.710 g cm^–3, = 2.143 mm^–1 and F(000) = 1608. The final R and wR are 0.0400 and 0.0720 for 5909 (I > 2.0(I)) unique reflections, and 0.0747 and 0.0799 for all 13825 reflections, respectively. The nine-coordinated [Eu^III(Ttha)]^3– complex anion has a pseudo-monocapped square antiprismatic structure in which the Ttha acts as an ninedentate ligand with four N atoms of amino groups and five O atoms of carboxylic groups actually, in addition, there is a non-coordinated free carboxylic group in the structure.     

Studies of the hydrated oxonium radical H3O·(H2O)n and the ammoniated ammonium radical NH4·(NH3)n by neutralized ion beam techniques

Neutralized ion beam studies of the clusters NH₄·(NH₃)_n and H₃O·(H₂O)_n,n = 0–3, and their fully deuterated analogs are presented. Stabilization of the hypervalent monomer radicals is found to accompany solvation. Cluster stability is found to decrease with increasing size. Reasons for this observation are discussed. Internally excited clusters are found to stabilize efficiently through the sequential loss of structural units (NH₃ or H₂O). The mixed isotopic dimer clusters (D₂¹⁸O)·D·(D₂¹⁶O) and (HDO)·D·(D₂O) are also investigated. Presence of the D₃¹⁶O radical structural unit is found to be crucial to dimer stability. This is consistent with the results of earlier investigations involving the monomer which showed the surprising lifetime progression τ(D₃¹⁶O) ≫; τ(D₃¹⁸O) ⩾ τ(H₃¹⁶O).     

Study of the solubility of components in the system Mg(ClO3)2-2NH2C2H4OH · H3C6H5O7-H2O

The solubility of components in the system Mg(ClO₃)₂-2NH₂C₂H₄OH · H₃C₆H₅O₇-H₂O was studied from the complete freezing temperature ?59.4°C to 20.0°C. A polythermal solubility diagram was constructed, in which the crystallization fields were determined for ice, Mg(ClO₃)₂ · 16H₂O, Mg(ClO₃)₂ · 12H₂O, Mg(ClO₃)₂ · 6H₂O, 2NH₂C₂H₄OH · H₃C₆H₅O₇ · H₂O, 2NH₂C₂H₄OH · H₃C₆H₅O₇, and two new compounds, [(HOC(CH₂COOH)₂COO)₂Mg · 2H₂O] and [HOC(CH₂COO)₂MgCOOH · 2H₂O], which were identified by chemical and physicochemical analysis methods.