Apparent molar heat capacities and volumes of aqueous electrolytes: CaCl2, Cd(NO3)2, CoCl2, Cu(ClO4)2, Mg(ClO4)2, and NiCl2

We have used a flow calorimeter and a flow densimeter for measurements leading to apparent molar heat capacities and apparent molar volumes of six 21 electrolytes in aqueous solution at 25°C. Results of these measurements have been used to derive apparent molar heat capacities and volumes at infinite dilution for all six electrolytes: CaCl₂, Cd(NO₃)₂, CoCl₂, Cu(ClO₄)₂, Mg(ClO₄)₂, and NiCl₂.     

Preparation and Properties of trans-[CoCl2(tmd>)2]Cl,and trans- and cis-[Co(NCS)2(tmd)2]NO3 (tmd: Tetramethylenediamine)

The cobalt(III) complexes [CoX₂(tmd)₂]⁺ (X: Cl^? or NCS^?, tmd: tetramethylenediamine), in which tmd forms a seven-membered chelate ring, have been prepared. Trans-[CoCl₂(tmd)₂]Cl was derived from [Co(NO₂)₂(tmd)₂]NO₃ in a fairly good yield. Two geometrical isomers, trans and cis, of [Co(NCS)₂-(tmd)₂]NO₃ were independently synthesized from trans-[CoCl₂(tmd)₂]Cl by different methods. The geometrical configurations of the isomeric pair of the NCS complex have been determined based on chromatographic behavior, electronic absorption spectra, and vibrational spectra. The d-d and CT absorption maxima of the NCS complex (18.7 x 10³cm^?1 (ε = 275) and 30.9 x 10³cm^?1 (ε = 3630) for the trans isomer, 19.3 x 10³cm^?1 (ε = 302) and 31.0 x 10³cm^?1 (ε = 4070) for the cis isomer) and the Co-N(amine) stretching frequency of trans-[CoCl₂(tmd)₂]Cl (418 cm^?1) have been compared with those of the corresponding ethylenediamine and trimethylenediamine complexes.     

Anhydrous Nitrates and Nitrosonium Nitratometallates of Manganese and Cobalt,M(NO3)2, NO[Mn(NO3)3], and (NO)2[Co(NO3)4]: Synthesis and Crystal Structure

Crystalline NO[Mn(NO₃)₃] ( I ) and (NO)₂[Co(NO₃)₄] ( II ) were synthesized by reaction of the corresponding metal and a liquid N₂O₄/ethylacetate mixture. I is orthorhombic, Pca2₁, a = 9.414(2), b = 15.929(3), c = 10.180(2) Å, Z = 4, R₁ = 0.0286. II is monoclinic, C2/c, a = 14.463(3), b = 19.154(4), c = 13.724(3) Å, β = 120.90(3), Z = 12, R₁ = 0.0890. Structure I consists of [Mn(NO₃)₃]^– sheets with NO⁺ cations between them. Two types of Mn atoms have CN_Mn = 7 and 8. Structure II is ionic containing isolated [Co(NO₃)₄]‐anions and NO⁺ cations with CN_Co = 8. Crystals of Mn(NO₃)₂ ( III ) and Co(NO₃)₂ ( IV ) were obtained by concentration of metal nitrate hydrate solutions in 100% HNO₃ in a desiccator with P₂O₅. III is cubic, Pa 3, a = 7.527(2) Å, Z = 4, R₁ = 0.0987. IV is trigonal, R 3, a = 10.500(2), c = 12.837(3) Å, Z = 12, R₁ = 0.0354. The three dimensional structure III is isotypic to the strontium and barium dinitrates. Structure IV contains a three dimensional network of interconnected Co(NO₃)_6/3 units with a distorted octahedral coordination environment of Co atoms. General correlations between central atom coordination and coordination modes of NO₃ groups are discussed.     

Kinetics and Mechanism of the Thermal Decomposition of M(NO3)2·nH2O (M=Cu,Co, Ni)

This paper presents the results of simultaneous DTA-TG-DTG and DSC studies on the thermal decomposition of Cu(NO3)2·3H2O, Co(NO3)2·6H2O and Ni(NO3)2·6H2O in an air atmosphere. The mechanism and enthalpies of the investigated processes were determined, as well as the kinetic parameters of the processes run under non-isothermal conditions by means of Kissinger's method. The dependence of the activation energy on the ionic radius of the cations building up the crystal lattices of the investigated compounds was also studied. This revised version was published online in July 2006 with corrections to the Cover Date.     

Solubility products of basic salts Cu2(OH)3NO3 and Hg3O2(NO3)2, determined from dilatometric data

The solubility products of basic salts Cu₂(OH)₃NO₃ and Hg₃O₂(NO₃)₂ were determined using dilatometric data.     

Synthesis and crystal structure of New Amminecopper(II) Nitrates: [Cu(NH3)2](NO3)2 and [Cu(NH3)](NO3)2

[Cu(NH₃)₂](NO₃)₂ ( I ) and [Cu(NH₃](NO₃)₂ ( II ) were synthesized by interaction of molten NH₄NO₃ with [Cu(NH₃)₄](NO₃)₂ and Cu(NO₃)₂ · 3 H₂O, respectively, at 180 to 195°C for 24 hr. According to X-Ray single crystal analysis, I is orthorhombic (sp. gr. Pbca) with a = 5.678(1), b = 9.765(2), c = 11.596(2) Å, Z = 4, R = 0.060; II is monoclinic (sp. gr. P2₁/c) with a = 6.670(1), b = 8.658(2), c = 9.661(2) Å, β = 101.78(2)°, Z = 4, R = 0.027. In both structures, the nearest coordination environment of Cu is a slightly distorted square formed by N (from NH₃) and O atoms (from NO₃ groups). The structure of I consists of centrosymmetrical [Cu(NH₃)₂](NO₃)₂ molecules linked by hydrogen bonds. The Cu? N and Cu? O distances are 1.98 and 2.01 Å, respectively. In II , the Cu? N distance is 1.95 Å, the Cu? O distances are 1.96, 2.02, and 2.03 Å. The [CuO₃NH₃] squares are connected by NO₃ bridges into zigzag chains, which are linked into layers by longer Cu? O interactions (2.31 Å). Obviously, the layers are additionally strengthened and held together by hydrogen bonds.     

Single crystal EPR of Cu(II) doped [Co(tbz)2(NO3)(H2O)]NO3: probe into copper-thiabendazole interaction

EPR of Cu(II) doped, low symmetry Co(II)-thiabendazole complex [Co(tbz)2(NO3)(H2O)](NO3) is investigated at 300 K. The spin Hamiltonian parameters are found to be orthorhombic with g33=2.305, g22=2.1351, g11=2.0626 and A33=147.0 x 10(-4), A22=33.5 x 10(-4) and A11=23.1 x 10(-4) cm(-1). Computer simulation of isofrequency plots reveal that the Cu(II) ions is substitutionally incorporated in the host lattice. Angular variation of the spectra shows the presence of two magnetic sites in the lattice. The low magnitude of A33 of the complex is rationalized in terms of admixture of d(x2-y2)/d(z2) ground state and delocalization of unpaired spin density onto the ligands.     

Thermodynamic Dissociation Constants for [MPy4(NO3)2]*2Py Clathrates (M=Mn,Co, Ni,Cu)

Abstract

Stoichiometry and thermodynamic parameters of the title clathrates dissociation have been studied with thermoanalytical and strain method techniques. The [MPy₄(NO₃)₂]^*2Py (M = Mn, Co, Ni) clathrates dissociate with collapsing clathrate porous phase and destruction of the host complex to give the respective tripyridine complexes and gaseous pyridine. The [CuPy₄(NO₃)₂]^*2Py dissociates with collapsing clathrate phase but giving the host [CuPy₄(NO₃)₂] complex as individual phase, with the tripyridine complex forming in further course of decomposition. The comparison of the thermodynamic dissociation parameters for the [MPy₄(NO₃)₂]^*2Py series with M = Mn, Co, Ni, Cu, Zn and Cd shows that the differences in the stability of the compounds do not correlate with structural parameters of the clathrates but depend on the nature of the metal cation in the host complex. Thermodynamic stability of these clathrate phases follows the general sequence of stabilty for complexes of the 3d transition metals known as Irwing-Williams sequence: Mn<Fe<Co<Ni<Cu>Zn. These results disclose the main issue of instability of the [MPy₄(NO₃)₂]^*2Py clathrates as instability of the respective host complexes.     

1,2-丙二醇水溶液玻璃化转变与结构松弛

为了考察水含量对1, 2-丙二醇水溶液玻璃化转变和结构松弛参数的影响, 用差示扫描量热法(DSC), 测量了5种高浓度1, 2-丙二醇水溶液(60%、70%、80%、90%、100%, w)玻璃化转变区域的表观比热容. 用5种降温速率(1、2、5、10、20 K·min-1)和10 K·min-1的升温速率获得玻璃化转变的相关参数. 玻璃化转变温度分析结果表明, 虽然水含量增加能从总体上降低体系的玻璃化转变温度, 但与纯羟基类多元醇相比, 水对1, 2-丙二醇的增塑作用并不显著. 结构松弛活化能计算结果表明, 体系水含量的增加能明显降低结构松弛活化能. 脆度分析结果表明, 随着体系水含量增加, 动力学脆度逐渐降低, 但热力学脆度是先升高后降低, 在80%左右达到最大值. 结构松弛协同重排域计算结果表明, 当浓度由60%增加至100%时, 玻璃化转变特征长度由2.79 nm增加至3.57 nm.     

Polymer-Enhanced Ultrafiltration of Fe(III) and Cu(II) Aqueous Solutions Using Poly(Vinyl Alcohol)-Alginic Acid/Cellulose Membranes

This study deals with the removal of Fe(III) and Cu(II) from dilute aqueous solutions using a polymer-enhanced ultrafiltration process. The ultrafiltration studies were carried out in batch stirred cell and the applied pressure was controlled by nitrogen gas. Properties of the composite membranes and its application in metal removal from aqueous solutions were studied. A composite poly(vinyl alcohol)-alginic acid/cellulose membranes were prepared by coating poly(vinyl alcohol)-alginic acid mixture solutions on the filter paper. Poly(vinyl alcohol) and alginic acid were also used as complexing agents to enhance the retention of metal ions. In the filtration of Fe(III) and Cu(II) solutions, the effects of membrane contents, pressure and pH on the retention and the flux were studied. The maximum retention of metals was found as 99% for Fe(III) solution at pressure of 45 psi, pH of 3 in the presence of poly(vinyl alcohol) as complexing agent by using 0.50 (w/v)% [(75 Poly(vinyl alcohol)/25 Alginic acid) (w/w)]/cellulose composite membranes.     

Synthese und Kristallstrukturen der Phosphanimin-Komplexe MCl2(Me3SiNPMe3)2 mit M = Zn und Co,und CoCl2(HNPMe3)2

Syntheses and Crystal Structures of the Phosphaneimine Complexes MCl₂(Me₃SiNPMe₃)₂ with M = Zn and Co, and CoCl₂(HNPMe₃)₂ The molecular complexes MCl₂(Me₃SiNPMe₃)₂ (M = Zn, Co) have been prepared by the reaction of the dichlorides of zinc and cobalt with Me₃SiNPMe₃ in CH₃CN and CH₂Cl₂, respectively, whereas the complex CoCl₂(HNPMe₃)₂ has been prepared by the reaction of CoCl₂ with NaF in boiling acetonitrile in the presence of Me₃SiNPMe₃. All complexes were characterized by IR spectroscopy and by crystal structure determinations. The complexes MCl₂(Me₃SiNPMe₃)₂ crystallize isotypically. ZnCl₂(Me₃SiNPMe₃)₂: Space group P2₁2₁2₁, Z = 4, 2677 observed unique reflections, R = 0.024. Lattice dimensions at ?70°C: a = 1243.6; b = 1319.0; c = 1464.7 pm. CoCl₂(Me₃SiNPMe₃)₂: Space group P2₁2₁2₁, Z = 4, 3963 observed unique reflections, R = 0,071. Lattice dimensions at ?80°C: a = 1236.3; b = 1317.4; c = 1457.6 pm. CoCl₂(HNPMe₃)₂ · CH₂Cl₂: Space group Pbca, Z = 8, 1354 observed unique reflections, R = 0.055. Lattice dimensions at ?80°C: a = 1247.3; b = 998.4; c = 2882.4 pm. All complexes have monomeric molecular structures, in which the metal atoms are coordinated in a distorted tetrahedral fashion by the two chlorine atoms and by the nitrogen atoms of the phosphaneimine molecules.     

The Reactivity of the Nitrate Radical (•NO3) in Aqueous and Organic Solutions

Rate constants for the nitrate (^•NO₃) radical reaction with alcohols, alkanes, alkenes, and several aromatic compounds were measured in aqueous and tert‐butanol solution for comparison to aqueous and acetonitrile values from the literature. The measured trends provide insight into the reactions of the ^•NO₃ radical in various media. The reaction with alcohols primarily consists of hydrogen‐atom abstraction from the alpha‐hydroxy position and is faster in solvents of lower polarity where the diffusivity of the radical is greater. Alkenes react faster than alkanes, and their rate constants are also faster in nonpolar solution. The situation is reversed for the nitrate radical reaction with the aromatic compounds, where the rate constants in tert‐butanol are slower. This is attributed to the need to solvate the NO₃⁻ anion and corresponding tropylium cation produced by the ^•NO₃ radical electron transfer reaction. A linear correlation was found between measured rate constants in water and acetonitrile, which can be used to estimate aqueous nitrate radical rate constants for compounds having low water solubility.     

EPR studies on Cu(3-amino, 5-methyl isoxazole)4 (ClO4)2 and Cu(3-amino, 5-methyl isoxazole)4 (NO3)2

EPR studies have been carried out on Cu(3-AMI)₄(ClO₄)₂ and Cu(3-AMI)₄(NO₃)₂[3-AMI = 3-amino, 5-methyl isoxazole] in polycrystalline and solution forms both at room (300 K) and liquid nitrogen temperature to obtain stereochemical information and the nature of the metal-ligand bond. Cu(II) hyperfine lines are obtained in these complexes even at room temperature, which is rare for a non-dilute Cu(II) complex. No ligand hyperfine (LHF) structure from bonded nitrogen is obtained in polycrystalline samples of these complexes at the above temperatures to allow the σ-bond strength to be estimated more accurately. The change in the spectral parameters and resolution at liquid nitrogen temperature (LNT) is negligible. The above parameters obtained in MeCN and pyridine solutions of Cu(3-AMI)₄(ClO₄)₂ obtained at LNT are of comparable magnitude with the polycrystalline values indicating less solvation in these solvents. LHF structure from bonded nitrogens observed on the perpendicular component of the above sample in forzen pyridine solution enabled us to calculate the σ-bond strength more accurately than the other cases. The species formed in the DMF (N, N′-dimethylformamide) solution of Cu(3-AMI)₄(NO₃)₂ is characteristic of a CuO₆ chromophore indicating stronger solvation in the above solution. The 4s-character in the ground state of Cu(II) in all the above cases was calculated to determine the relative strengths of axial fields.     

Diffusion of Solvents and Cations in Porous Sol-Gel Glass

Diffusion coefficients for water, cyclohexane, toluene, chloroform, acetone and acetonitrile in porous sol-gel glass were determined using the diaphragm and radioactive tracer techniques. Polar solvents were found to diffuse faster than nonpolar solvent within porous sol-gel glass. The diffusion coefficients of Nd³⁺ and Er³⁺ inside porous sol-gel glass were determined from concentration profiles within monoliths impregnated by 1.6 M rare earth salts dissolved in either acetone or water. To study the effects of ligands on the diffusion, four different erbium salts were used: nitrate, chloride, bromide, and perchloride. It was found that the diffusion rate increases with decreasing radius of rare earth coordination sphere.     

Synthesis and X-Ray Structure of New Copper(II) Nitrates: Cu(NO3)2 · H2O and β-modification of Cu(NO3)2

Blue crystals of a Cu(NO₃)₂ · H₂O were synthesized by interaction of CuO with boiling 100% HNO₃. Stable β-Cu(NO₃)₂ modification was obtained by the sublimation of copper(II) nitrate in evacuated ampoule over the 150→100°C temperature gradient for 24 hr. According to X-Ray single crystal analysis Cu(NO₃)₂ · H₂O is monoclinic with a = 6.377(1), b = 8.548(1), c = 9.769(1) Å, β = 100.41(1)°, Z = 4, and space group P2₁/c. β-modification Cu(NO₃)₂ is orthorhombic with a = 14.161(5), b = 7.516(3), c = 12.886(2) Å, Z = 12, and space group Pbcn. In the both structures Cu atoms are square coordinated by 4 O atoms at the distances ranging from 1.92 to 2.02 Å. In each structure there are also additional Cu? O bonds with the distance of 2.33 or 2.35 Å and some weaker ones with the distances in the range of 2.65–2.72 Å. In the Cu(NO₃)₂ · H₂O structure the [CuO₄] squares are connected by the bridging NO₃ groups into zigzag chains, which are linked into layers by the longer Cu? O bonds. In the β-Cu(NO₃)₂ structure the [CuO₄] fragments of two types are joined by the bridging NO₃ groups in a three-dimensional framework. Some correlations were found between N? O distances and coordination functions of O atoms.     

Interaction of Co(II), Ni(II), and Cu(II) with Quartz Surface in Aqueous Solutions at Varied pH

Sorption%sol;desorption of Co(II), Ni(II), and Cu(II) on quartz was studied in aqueous solutions at pH 3.0, 5.0, and 7.3 [for Co(II) and Ni(II)] and 3.0 and 5.0 [for Cu(II)].     

四元轻稀土硝酸盐水溶液体系{H2O+La(NO3)3+Pr(NO3)3+Nd(NO3)3}的热力学研究

在298.15 K条件下, 利用等压法研究了四元轻稀土硝酸盐水溶液{H2O La(NO3)3 Pr(NO3)3 Nd(NO3)3}及其3个二元亚系{H2O La(NO3)3}, {H2O Pr(NO3)3}和{H2O Nd(NO3)3}的热力学性质. 以NaCl或CaCl2水溶液为参考溶液, 测定了不同水活度条件下该四元溶液的渗透系数及各溶质组元的活度系数. 实验结果表明, 上述四元系与其3个二元亚系之间存在简单共性, 在实验误差允许范围之内(|Δ|≤0.0010), 该四元系符合偏理想溶液模型.