Thermodynamics of Sr(NO3)2 and Cd(NO3)2 in aquo-organic solvents from conductance data

The ion-solvent interaction of Sr(NO₃)₂ and Cd(NO₃)₂ in 10, 20 and 30 wt.% organic solvent (dioxane, glycol, methyl alcohol)-water mixtures at different temperatures has been studied using electrolytic conductivity data. The dissociation constant of the ion-pair Sr(NO₃)⁺ and Cd(NO₃)⁺ has been calculated along with ΔG⁰_t, ΔG⁰_t(cl) and ΔG⁰_t(ch). The ion pairs interact with the solvents and the interaction is of the order dioxane+water>methyl alcohol+water>glycol+water.     

Metal‐Sensitive Hydrothermal Synthesis and Structural Characterization of a Mixed‐Metal and Porous Coordination Polymer Containing 2,3‐Pyridinedicarboxylate

The hydrothermal reaction of 2,3‐pyridinedicarboxylic acid (2,3‐H₂pda) with a mixture of Cd(NO₃)₂ and Ni(NO₃)₂ afforded a coordination polymer, [CdNi(2,3‐pda)₂(H₂O)₃]_∞ ( 1 ); in contrast, that with a mixture of Cd(NO₃)₂ and Zn(NO₃)₂ surprisingly produced a discrete molecule, trans‐[Cd(3‐pa)₂(H₂O)₄] ( 2 ) (3‐pa^? = 3‐pyridinecarboxylate). Since a direct reaction between a single metal salt, Cd(NO₃)₂ or Zn(NO₃)₂, and 3‐pyridinecarboxylic acid (3‐Hpa) under similar hydrothermal conditions yielded different coordination polymers containing 3‐pa^?, it appears that the apparently thermal decarboxylation from ligated 2,3‐pda^2? to 3‐pa^? occurs after complexation of both metal cations, Cd(II) and Zn(II). A new coordination mode, formed for 2,3‐pda^2? in structure 1 , appears to help formation of microporous channels by piling up the observed 2D hydrogen‐bonded heteropolynuclear layers. Each channel apparently consists of two interpenetrating 6³ Cd(II) and Ni(II) nets.     

CONTACT STABILIZATION OF HOST COMPLEX MOLECULES DURING CLATHRATE FORMATION: THE PYRIDINE-ZINC NITRATE AND THE PYRIDINE-CADMIUM NITRATE SYSTEMS

Abstract

Clathrate formation ranges of the phase diagrams of two binary systems Py-Zn(NO₃)₂ and Py-Cd(NO₃)₂ (Py = pyridine) were studied. A clathrate of composition [MPy₄(NO₃)₂]·2Py (M = Zn, Cd) was observed in each of the systems. The space group Ccca (orthorhombic system) and the parameters of the unit cells of both clathrates were determined by X-ray analysis of their single crystals. The data obtained show them to be isostructural with the clathrate [NiPy₄(NO₃)₂]·2Py whose structure is known and suggest the actual presence of the host molecules trans-[MPy₄(NO₃)₂] (M = Zn,Cd) inside the clathrate phases. Host complexes do not form as separate compounds but can only arise in clathrate phases due to contact stabilization by the guest molecules. Both Zn- and Cd-clathrates are of constant composition and melt incongruently at 62.3(6) and 106.0(5)°C, respectively, yielding the complexes [ZnPy₃(NO₃)₂] and [CdPy₃(NO₃)₂], these melting congruently at 131.4(5) and 169.5(5)°C, respectively. During thermal decomposition under quasi-equilibrium conditions with different pressures of the liberating pyridine both clathrates also decompose in one stage, giving [MPy₃(NO₃)₂] complexes. The results obtained are discussed in relation to a number of other systems with Schaeffer's and Hofmann-lwamoto's clathrates in which contact stabilization occurs or might be expected to occur.     

Thermodynamics of Sr(NO3)2 and Cd(NO3)2 in mixed solvents from viscosity data

The viscosities of Sr(NO₃)₂ and Cd(NO₃)₂ have been determined in dioxane, glycol and methyl alcohol+water mixtures at 10, 20 and 30% by weight. The B values have been computed at different temperatures both from the Jones—Dole and Das's equation. From the B values, the effective rigid molar volume, its change with % of organic solvent, temperature and the ion—solvent interaction have been inferred. Activation parameters have also been calculated and the structure breaking effect has been deduced.     

Features of Component Interaction in Concentrated Solutions of Multicomponent Systems

Classical complex formation processes in the multicomponent systems Cd(NO₃)₂-MCl-H₂O (M = Li, Cs) occur at preeutectic concentrations of salts. At posteutectic concentrations of salts the formation of cadmium chloride complexes is of structurally enforced nature and depends on the type of the cybotactic group dominating in the solution. The example of the system Cd(NO₃)₂-LiCl-H₂O was used to show that the law of mass action does not apply to systems in which structurally enforced processes occur. Differences in the solubility of MCl (M = Li, Cs, Na) in concentrated solutions of cadmium nitrate are proposed to explain in terms of differences in interactions of cybotactic groups formed by cadmium nitrate and the corresponding chloride.     

The effect of Cd(II) complexes with nicotinamide (NA) on microalgae growth,production of chlorophylls,oxygen evolution and Cd adsorption

The effects of Cd [Cd(NO₃)₂] and its complexes with nicotinamide (NA) [Cd(ac)₂(NA)₂, Cd(NCS)₂(NA)₂, Cd(NCSe)₂(NA)₂] were examined by using the algae Scenedesmus quadricauda and Chlorella vulgaris as a function of Cd speciation in a well-defined aqueous medium. The parameters observed during the experiments were algal growth inhibition, chlorophyll a and b content, oxygen evolution and Cd adsorption by algal cells. With regard to growth and production of chlorophylls (Chla, Chlb), the most toxic compound was Cd(NO₃)₂. On the basis of EC50 values for these parameters, the following rank order can be arranged for both algae: Cd(NO₃)₂?>?Cd(ac)₂(NA)₂?>?Cd(NCS)₂(NA)₂?>?Cd(NCSe)₂(NA)₂. While Cd(NO₃)₂ in EC50 concentration for algal growth also reduced oxygen evolution nearly by half, all Cd(II) complexes used in EC50 concentrations for the same parameter reduced oxygen evolution less. When a comparison was done for Cd(NO₃)₂, all Cd(II) complexes stimulated oxygen evolution in both algal species. Base on the adsorbed Cd quantity, the tested compounds for both algae could be arranged in the following sequence: Cd(NO₃)₂?>?Cd(ac)₂(NA)₂?>?Cd(NCS)₂(NA)₂?>?Cd(NCSe)₂(NA)₂. The results confirmed that the adsorbed Cd amount markedly exerted its influence on algal growth and intensity of their physiological processes. Higher sensitivity was confirmed for alga S. quadricauda, which adsorbed a higher amount of Cd, and reduction of all observed parameters in this alga was more intensive than in C. vulgaris. As less toxic for both algae was confirmed the complex Cd(NCSe)₂(NA)₂.     

Solubility and solid phases in the systems zinc nitrate-dimethylcarbamide-water and cadmium nitrate-dimethylcarbamide-water at 25°C

Solubility isotherms have been studied in the systems Zn(NO₃)₂-(CH₃)₂NCONH₂-H₂O and Cd(NO₃)₂-(CH₃)₂NCONH₂-H₂O at 25°C. Crystallization fields have been determined for the congruent-melting compounds Zn(NO₃)₂ · 4(CH₃)₂NCONH₂ · 2H₂O (I) and Cd(NO₃)₂NCONH₂ (II). The compounds have been characterized by chemical analysis, differential thermal analysis, powder X-ray diffraction, and IR spectroscopy.     

PMR study of Cd(II) complexes with 2,2′-bipyridine

The NMR method has been used to study the structure of the complexes [Cd(bipy)]SO₄.4H₂O, [Cd(bipy)](NO₃)₂.2H₂O, [Cd(bipy)₂](NO₃)₂.$\text{1}\text{2}$H₂O and [Cd(bipy)₃](NO₃)₂.7H₂O. The influence of the central ion and of diamagnetic currents of the rings in these complexes on the PMR spectrum has been investigated. In the complexes [Cd(bipy)](NO₃)₂.2H₂O and [Cd(bipy)]SO₄.4H₂O two kinds of hydration isomers, with different PMR spectra, have been obtained.     

Physicochemical investigation of the solubilization of ytterbium nitrate in AOT reverse micelles and liquid crystals

A wide investigation of the solubilization of the water-soluble salt Yb(NO₃)₃ in sodium bis(2-ethylhexyl)sulfosuccinate (AOT) reverse micelles and AOT liquid crystals has been carried out. After saturation of water/AOT/organic solvent w/o microemulsions with pure Yb(NO₃)₃, the Yb(NO₃)₃/AOT composites were prepared by complete evaporation under vacuum of the volatile components (water and organic solvent) of the salt-containing microemulsions. It was observed that these composites can be totally dissolved in pure n-heptane or CCl₄, allowing the solubilization of a noticeable amount of Yb(NO₃)₃ in quite dry apolar media. By UV–vis–NIR, FT-IR, and ¹H NMR spectroscopies, some information on the state of Yb(NO₃)₃ within AOT reverse micelles were acquired, whereas by small angle X-ray scattering (SAXS), it has been ascertained that Yb(NO₃)₃ is quite homogeneously distributed as very small clusters among the reverse micelles. An analysis of SAXS and wide-angle X-ray scattering spectra of Yb(NO₃)₃/AOT composites leads to the hypothesis that, also in these systems, Yb(NO₃)₃ is dispersed in the surfactant matrix as very small clusters.     

Synthesis and Characterization of a Novel Energetic Complex [Cd(DAT)6](NO3)2 (DAT = 1,5‐diamino‐tetrazole) with High Nitrogen Content

The novel high nitrogen‐containing energetic complex [Cd(DAT)₆](NO₃)₂ was synthesized by reaction of Cd(NO₃)₂·6H₂O with 1,5‐diamino‐tetrazole (DAT). It was characterized by elemental analysis, FT‐IR spectroscopy and single‐crystal X‐ray diffraction analysis. The central Cd²⁺ ion is coordinated by six nitrogen atoms from six DAT ligand molecules to form a hexacoordinate distorted octahedral compound. The [Cd(DAT)₆](NO₃)₂ molecules are linked together through two types of hydrogen bonds thus forming a stable three‐dimensional net structure. The thermal decomposition mechanism of [Cd(DAT)₆](NO₃)₂ was investigated by DSC and TG/DTG analyses and FT‐IR spectroscopy. The kinetic parameters of the exothermic process were studied by using Kissinger’s and Ozawa–Doyle’s methods.     

Chemical effects of heavy metals on the hydration of calcium sulphoaluminate 4CaO·3Al2O3·SO3

The system 4CaO·3Al₂O₃·SO₃-CaSO₄·2H₂O-Ca(OH)₂ was hydrated in the presence of ten dopants, specifically soluble salts of heavy metals.When added in 10% amount, the effect of each salt is strongly evident at shorter curing times, the hydration kinetics being more favoured in the order Pb(NO₃)₂2CrO₄< Cd(NO₃)₂< Zn(NO₃)₂t~Mn(NO₃)₃=K₂MoO₄3)₂3)₂3)₃3)₃. At longer curing times the differences among the systems decrease significantly.The 28-day compressive strength is almost the same for all the systems except those containing Pb(NO₃)₂, K₂MoO₄ and K₂CrO₄.     

Thermal decomposition of [Cd(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

Thermal decomposition of [Cd(NH₃)₆](NO₃)₂ was studied by thermogravimetry (TG) with simultaneous differential thermal analysis (SDTA) for two samples and at two different sets of measurement parameters. The gaseous products of the decomposition were on-line identified by evolved gas analysis (EGA) with a quadruple mass spectrometer (QMS). The decomposition of the title compound proceeds, for both cases, in the three main stages. In the first stage, deammination of [Cd(NH₃)₆](NO₃)₂ to [Cd(NH₃)](NO₃)₂ undergoes by three steps and 5/6 of all NH₃ molecules are liberated. At second stage the liberation of residual 1/6NH₃ molecules and the formation of Cd(NO₃)₂ undergoes. However, during this process simultaneously a two-step oxidation of a part of ammonia molecules also takes place. In a first step as a result a mixture of ammonia, water vapour and nitrogen is formatted. At the second step, subsequent oxidation of a next part of NH₃ molecules undergoes. As a result, a mixture of nitrogen oxide, nitrogen and water vapour is formatted, what for these both steps clearly indicates the EGA analysis. The third stage of the thermal decomposition is connected with the melting and subsequent decomposition of residual Cd(NO₃)₂ to oxygen, nitrogen dioxide and solid CdO. Additionally, third sample was measured by differential scanning calorimetry (DSC) and the results are fully consistent with those obtained by TG.     

Syntheses and characterization of mixed-anion cadmium(II) complexes,structural characterization of [Cd(phen)2(NO2)1.65(NO3)0.35], as a new eight-coordinate Cd(II) complex

New mixed-anion cadmium(II) complexes of 2,2′-bipyridine (bpy) and 1,10-phenanthroline (phen) ligands, [Cd(phen)₂(NO₂)_1.65(NO₃)_0.35] and Cd(bpy)(ClO₄)(CH₃COO) have been synthesized and characterized by elemental analysis, IR-, ¹H NMR-, ¹³C- NMR and ¹¹³Cd NMR spectroscopy. The single crystal X-ray data of [Cd(phen)₂(NO₂)_1.65(NO₃)_0.35] show the complex to be a monomer and that the Cd atom has an unsymmetrical eight-coordinate geometry, being coordinated by four nitrogen atoms of ‘phen’ ligands and four oxygen atoms of the nitrite and nitrate anions. There is a short π–π stacking interaction between parallel aromatic rings.     

Cationic Cd(II) metal − organic framework based on tetrakis(1,2,4-triazol-1-yl)methane

Abstract

Solvothermal reaction of a multidentate ligand (tetrakis[4-(1-triazolyl)phenyl]-methane (ttpm)), with Cd(NO₃)₂ afforded a cationic Cd(II) coordination polymer {[Cd(ttpm)·DMSO]·2NO₃}_n. Single-crystal X-ray diffraction analyses showed that ttpm belonged to the tetragonal space group I4₁/a, and 1 was a 2-D (4,4) network. 1-D channels along the c direction exist in the 3D stacking map to accommodate the charge-balancing NO₃^? anions. N₂ adsorption/desorption experiments showed the framework had a BET surface area of 11.36?m²·g^?1. Compared with luminescence of ttpm, 1 showed red-shifted luminescence spectra with higher intensity from the more rigid arrangement of the π systems.     

Über die Veränderung der mittleren Ionenaktivitäts-koeffizienten der Komponenten in Dreistoffsystemen,aus denen reine Salze kristallisieren

About the Change of Mean Ionic-activity Coefficients of the Components in Triple Systems, from which Pure Salts Crystallize The isotherms of solubility of the systems Mg(NO₃)₂? Cd(NO₃)₂? H₂O and MgSO₄? CdSO₄? H₂O are studied at 25°C. Using the GIBBS -DUHEM equation the mean ionic-activity coefficients (γ±) in saturated triple solutions are calculated by a simplified method. The course of change of γ± along the isotherm of solubility for systems of simple eutectic type is shown.     

Synthesis and spectral studies of new macrocyclic Schiff base Cu(II), Ni(II), Cd(II), Zn(II), Pb(II), and La(III) complexes containing pyridine head unit

1,6-Bis(2-formylphenyl) hexane (I) was derived from 1,6-dibromohexane with salicylaldehyde and K₂CO₃ and the ligand (L) was derived from compound I and 2,6-diaminopyridine. Then, the Cu(II), Ni(II), Pb(II), Zn(II), Cd(II), and La(III) complexes with L were synthesized by the reaction of this ligand and Cu(NO₃)₂ · 3H₂O, Ni(NO₃)₂ · 6H₂O, Pb(NO₃)₂, Zn(NO₃)₂ · 6H₂O, Cd(NO₃)₂ · 6H₂O, and La(NO₃)₃ · 6H₂O, respectively. The ligand and its metal complexes were characterized by elemental analysis, IR, ¹H and ¹³C NMR, UV-Vis spectra, magnetic susceptibility, conductivity measurements, and mass spectra. All complexes are diamagnetic and the Cu(II) complex is binuclear. The article is published in the original.     

Vibrational spectral studies of ion-ion and ion-solvent interactions. II. Zinc nitrate in water/dioxane mixtures

Raman and infrared spectral data have been collected forp-dioxane and solvated and bound nitrate ions for Zn(NO₃)₂/p-dioxane/water systems. It is concluded that Zn²⁺ is preferentially solvated by water and that this aquation is also responsible for a lower concentration of ion pairs than is found for methanol/Zn(NO₃)₂ solutions for which the dielectric constant of the bulk solvent is similar. Values of K₁ (M^–1), the association constant for Zn(NO₃)⁺, are 0.22±0.02 (2/1 solvent,D=12.6) and 0.071±0.01 (4/1 solvent,D=33.0). The log K₁ against 1/D plot is not linear.     

Metal nitrate driven nitro Hunsdiecker reaction with α,β-unsaturated carboxylic acids under solvent-free conditions

Hunsdiecker reactions with α,β-unsaturated carboxylic acids were conducted under solvent-free conditions in the presence of a few drops of HNO₃ together with a variety of metal nitrates [Mg(NO₃)₂, Sr(NO₃)₂], Al(NO₃)₃, Ca(NO₃)₂, Ni(NO₃)₂, Cd(NO₃)₂, Zn(NO₃)₂, Hg(NO₃)₂, AgNO₃, ZrO(NO₃)₂, UO₂(NO₃)₂, Th(NO₃)₂] or ammonium nitrate. α,β-Unsaturated aromatic carboxylic acids underwent nitro decarboxylation to afford β-nitro styrenes in moderate to good yields, while α,β-unsaturated aliphatic carboxylic acids underwent decarboxylation to yield the corresponding nitro derivatives.     

Structure cristalline et polymorphisme du nitrate de cadmium anhydre

Cd(NO₃)₂ undergoes a phase transition at 160°C. The high temperature form is cubic and isomorphic with M(NO₃)₂ (M = Ba, Ca, Sr, Pb). The crystal structure of the low temperature phase has been solved by X-ray diffraction at 20°C, using 774 independent reflections collected with a 4-circle diffractometer. The dimensions of the orthorhombic unit cell are: $\text{a ? c = 7.5073 (14)}$ Å, b = 15.3692 (35) Å, Z = 8, space group Pca2₁. The structure has been refined to the final weighted R = 0.044. The cadmium atoms are nearly in a face-centered arrangement. Each cadmium is octahedrally surrounded by six oxygen, the CdO distances varying from 2.34 to 2.46 Å. Each nitrate group belongs through its three oxygens to three different octahedra. The structural change cubic Cd(NO₃)₂ → orthorhombic Cd(NO₃)₂ is characterized by a small rotation of NO₃ groups in their plane; the face-centered array of cadmium atoms is only slightly modified. The coordination of cadmium atoms changes from 12 to 6, and the approximate doubling of parameter (b) as well as the difference of symmetry can be explained by two different directions of rotation of the NO₃ groups situated in the same plane.     

Synthesis and characterization of three Cd(II) Schiff-base macrocyclic N3O2 complexes

Three polyamine ligands of N1-(2-nitrobenzyl)-N1-(2-aminoethyl)ethane-1,2-diamine (L₁), N1-(2-nitrobenzyl)-N1-(2-aminoethyl)propane-1,3-diamine (L₂) and N1-(2-nitrobenzyl)-N1-(3-aminopropyl)propane-1,3-diamine (L₃) were synthesized and their cyclocondensation with 2-[2-(2-formyl phenoxy)ethoxy]benzaldehyde (L₄) in the presence of various metal(II) ions was examined. These reactions only in the presence of a stoichiometric amount of cadmium(II) nitrate gave the related cadmium(II) macrocyclic Schiff-base complexes. In all the other cases no cyclic complexes have been obtained and metal(II) polyamines were the only products. The complexes have been studied with IR, ¹H NMR, ¹³C NMR, DEPT, COSY, HMQC and microanalysis. The crystal structures of [Cd(NO₃)(L₅)(μ-NO₃)Cd(NO₃)(L₅)]0.5Cd(NO₃)₄ (1) and [CdL₅(NO₃)(CH₃OH)]ClO₄ (2) have been also determined.