Dielectric constant and dielectric relaxation in aqueous solutions of K<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] and K<Subscript>2</Subscript>[PtCl<Subscript>4</Subscript>]

The MW-dielectric properties of aqueous solutions of K₂[PtCl₄] (I) and K₂[PdCl₄] (II) were studied at 298 and 313 K in the frequency range (12–25 GHz) corresponding to the maximum dielectric constant dispersion for water and aqueous solutions of these salts. The low-frequency conductivities were measured. The static dielectric constant, the dielectric relaxation time, and the enthalpy of activation of the dielectric relaxation of the solutions were determined. Compared to pure water, in solutions of salts I and II, the orientational mobility of water molecules is increased and the network of H-bonds is violated more strongly than that of most other ions with hydrophilic hydration. It was demonstrated for the first time that dielectric spectroscopy can be used for analyzing complexation processes in systems containing aqua and hydroxo chloride complexes of metals.     

Be<Subscript>2</Subscript>(OH)<Subscript>2</Subscript>CO<Subscript>3</Subscript> solubility in carbonate and fluoride aqueous solutions

Be₂(OH)₂CO₃ solubilities at 25°C in 0.7 M NaClO₄ solutions containing variable NaHCO₃ and Na₂CO₃ concentrations has been experimentally determined. The solubilities increase with increasing carbonate alkalinity. The results of the experiments do not contradict the suggestion that the mixed hydroxocarbonate complex Be₂(OH)₂CO ₃ ^2? is the major beryllium solute species. At fluoride concentrations higher than 250 μmol/L, the Be₂(OH)₂CO₃ solubilities noticeably increase as a result of the formation of beryllium fluoride complexes.     

Synthesis and X-ray investigation of Rb<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>] and Cs<Subscript>2</Subscript>[Pd(NO<Subscript>3</Subscript>)<Subscript>4</Subscript>]

Powder and single crystal X-ray diffraction studies have been performed for anhydrous nitrate complexes Rb₂[Pd(NO₃)₄] (I) and Cs₂[Pd(NO₃)₄] (II). Crystal data for I: a = 7.843(1) Å, b = 7.970(1) Å, c = 9.725(1) Å; β = 100.39(1)°, V = 597.9(1) Å ³, space group P2₁/c, Z = 2, d _calc = 2.918 g/cm³; for II: a = 10.309(2) Å, b = 10.426(2) Å, c = 11.839(2) Å; β = 108.17(3)°, V = 1209.0(4) ų, space group P2₁/c, Z = 4, d ^calc = 3.408 g/cm³. The structures are formed by isolated [Pd(NO₃)₄]^2? complex anions and alkali metal cations. The plane-square environment of the Pd atom is formed from the oxygen atoms of the monodentate nitrate groups. The geometrical characteristics of the complex anions are analyzed. Compound II has a short contact Pd...Cs 3.252 Å.     

Crystal Structure of Tl<Subscript>2</Subscript>[NbCl<Subscript>6</Subscript>] and Tl<Subscript>2</Subscript>[NbBr<Subscript>6</Subscript>]

Single crystals of Tl₂[NbCl₆] (1) and Tl₂ [NbBr₆] (2) are obtained as black needles on heating TlCl, Nb, S₂Cl₂ (1) and Tl, Nb, and Br₂ at 400°C (2). Tl₂NbBr₆ also forms in the reaction of TlBr, Nb, Br₂, and S at 500°C. Both compounds crystallize in the K₂[PtCl₆] structure type to form non-distorted octahedral [NbХ₆]^2– anions (Nb–Cl 2.397(4) Å and Nb–Br 2.516(2) Å). The magnetic properties of Tl₂[NbBr₆] in a range 5-300 K indicate an antiferromagnetic interaction between Nb⁴⁺ ion spins (d¹, S = 1/2). On cooling, the compound becomes a noncollinear ferromagnet with T_c = 23 K.     

Crystal structure and EPR spectra of (Bu<Subscript>4</Subscript>N)<Subscript>2</Subscript>[V(dmit)<Subscript>3</Subscript>]

The tris-chelate complex of vanadium(IV) (Bu₄N)₂[V(dmit)₃] is prepared from VCl₃ and (Bu₄N)₂[Zn(dmit)₂] (dmit = isotrithionedithiolate C₃S₅ ^2–) and characterized by single crystal XRD and mass spectrometry. The complex crystallizes in the space group Pna2₁ and has a distorted octahedral environment of vanadium. The complex is paramagnetic and gives a characteristic EPR spectrum in both solution and solid phase. The g factors and hyperfine interaction constants are determined.     

Synthesis and Selected Physicochemical Properties of Complex Na<Subscript>2</Subscript>[Zr(MoO<Subscript>4</Subscript>)<Subscript>3</Subscript>]

The interaction of Zr(NO₃)₄ and Na₂MoO₄ in an aqueous medium has been studied by the method of residual concentrations at 20°C. The compound Nа₂[Zr(MoO₄)₃] is formed starting at the molar ratio Zr(NO₃)₄/Na₂MoO₄ ≥ 0.66. The compound has been characterized by X-ray diffraction, IR spectroscopy, and thermal analysis.     

Phase formation of complex phosphate K<Subscript>4</Subscript>Ti<Subscript>3</Subscript>Ni(PO)<Subscript>4</Subscript> in K<Subscript>2</Subscript>O-P<Subscript>2</Subscript>O<Subscript>5</Subscript>-TiO<Subscript>2</Subscript>-NiO melt solutions

The principles of complex phosphate crystallization in K₂O-P₂O₅-TiO₂-NiO solution melts are studied for the ratios K/P = 0.7?1.4, Ti/P = 0.15, and Ni/Ti = 0.1?2.0. The phase-formation field and parameters are determined for a new complex phosphate K₄Ti₃Ni(PO₄)₆, which is isostructural to langbeinite. A single-crystal X-ray diffraction experiments is carried out for this phosphate (space group P2₁3, a = 9.8247(10) Å).     

Influence of the conformers of the ligand 2-methylamino-1-phenylpropan-1-ol (HA) in the complexes (H<Subscript>2</Subscript>A)<Subscript>2</Subscript>[PdCl<Subscript>4</Subscript>] on their state in solutions and their biological activity

The systems Pd(II)-Cl^?-HA-H₂O (where HA are the conformers of 2-methylamino-1-phenylpropan-1-ol) were studied. The acid dissociation constants of the ligands HA and the resulting complexes were determined by pH-metric titration and mathematical modeling. The pH-distribution diagram of the complex species in the system containing different HA conformers was obtained. The complexes (H₂A)₂[PdCl₄] were obtained and structurally characterized; their toxicity and radioprotective effects were estimated. The biological activity of the complexes was found to depend on both the ligand basicity and the hydrogen bonding system formed by different conformers of the ligand in the cation-anion complexes.     

Crystal structure of new ammonium fluoroindate(III) (NH<Subscript>4</Subscript>)<Subscript>2</Subscript>[InF<Subscript>5</Subscript>]

A new indium(III) fluoride complex with the ammonium cation (NH₄)₂[InF₅] is synthesized and its crystal structure is studied. The structure of (NH₄)₂[InF₅] is formed of NH₄ ⁺ cations and complex [InF₅]^2– anions. The In atom in the complex anion surrounded by four terminal and two bridging F atoms forms an almost regular octahedral coordination polyhedron (CN 6) with two terminal F atoms in the axial positions and two terminal and two bridging F atoms in the equatorial plane. Through bridging F atoms, the InF6 polyhedra are arranged in polymer trans- vertex-connected corrugated anion chains (InF₅) _n ^2n? directed along the c axis. The N–H?F hydrogen bonds organize the chains in a three-dimensional framework.     

Synthesis and study of (hexacaprolactam)trionium dodecamolybdophosphate (C<Subscript>6</Subscript>H<Subscript>11</Subscript>NO)<Subscript>6</Subscript>H<Subscript>3</Subscript>[PMo<Subscript>12</Subscript>O<Subscript>40</Subscript>]

(Hexacaprolactam)trionium dodecamolybdophosphate (C₆H₁₁NO)₆H₃[PMo₁₂O₄₀] has been prepared and studied by means of chemical and X-ray diffraction analysis as well as NMR and IR spectroscopy.     

Chemistry of the CARBEX process: Identification of absorption bands of the ligands in the electronic spectra of aqueous solutions of Na<Subscript>4</Subscript>[UO<Subscript>2</Subscript>(O<Subscript>2</Subscript>)CO<Subscript>3</Subscript>)<Subscript>2</Subscript>]

On the basis of consideration of dissociation, hydration, association, and ligand exchange, the assignment of absorption bands in the electronic spectra of aqueous solutions of the Na₄[UO₂(O₂)CO₃)₂] complex has been performed. It has been demonstrated that the absorption in the range 190–400 nm is caused by the oxygen atoms of the O₂^2- and CO₃^2- groups and hydration water molecules of dissociated and neutral complex species Na₃[UO₂(O₂)(CO₃)₂]^–, Na₂[UO₂(O₂)(CO₃)₂]^2–, and Na₄[UO₂(O₂)(CO₃)₂].     

Complexation of Zn<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>] with M<Superscript>2+</Superscript> (M = Mn,Co, Ni,Cu, Cd) in Zn<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>] gelatin-immobilized matrices

Electrophilic substitution reactions Zn²⁺ M²⁺ (M = Mn, Co, Ni, Cu, Cd) in thin gelatin layers with immobilized zinc(II) hexacyanoferrate brought in contact with the aqueous solutions of d-element chlorides are studied. In all cases (except for Mn(II)), Zn atoms are partially replaced by all metals in question with the formation of the corresponding binuclear ZnM hexacyanoferrates(II). No complete replacement of Zn(II) to mononuclear hexacyanoferrate(II) of substituting metal occurs in neither of the cases.Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 2, 2005, pp. 110–116. Original Russian Text Copyright © 2005 by Tatarintseva, Mikhailov, Naumkina, Lygina.     

Constant current anodic stripping chronopotentiometric determination of uranium in uranium mineral ores via accumulation of K<Subscript>2</Subscript>UO<Subscript>2</Subscript>[Fe(CN)<Subscript>6</Subscript>] on the palladium plated aluminum electrode

In the present work the uranyl hexacyanoferrate (K₂UO₂[Fe(CN)₆]) is deposited on the palladized aluminum (Pd-Al) electrode from a \textUO₂^{2 +} + \textFe( \textCN )₆ ^{- 3} {\text{UO}}_{2}^{2 + } + {\text{Fe}}\left( {\text{CN}} \right)_{6}^{ - 3} solution. Then the anodic stripping chronopotentiometry (ASCP) was used to strip the K₂UO₂[Fe(CN)₆] from the Pd-Al surface. The operational conditions including: pH, K₃Fe(CN)₆ concentration, deposition potential, deposition time and stripping current were optimized. The ASCP calibration graph was linear in concentration range 10–460 μM. of \textUO₂^{2 +} {\text{UO}}_{2}^{2 + } and the detection limit was 8.5 μM. The interference of some concomitant ions during the deposition process of K₂UO₂[Fe(CN)₆] was studied. The proposed method was successfully applied for analysis of some uranium mineral ores.     

Iron(II) complexes [Fe(DfgH)<Subscript>2</Subscript>(3-CONH<Subscript>2</Subscript>-Py)<Subscript>2</Subscript>] and [Fe(DfgH)<Subscript>2</Subscript>(4-COOC<Subscript>2</Subscript>H<Subscript>5</Subscript>-Py)<Subscript>2</Subscript>]: Synthesis and structures

The complexes [Fe(DfgH)₂(3-CONH₂-Py)₂] (I) and [Fe(DfgH)₂(4-COOC₂H₅-Py)₂] (II), where DfgH₂ is α-benzyl dioxime, were obtained and examined by X-ray diffraction analysis. The equatorial planes of the coordination octahedra of the metal ions consist of two monodeprotonated α-benzyl dioxime residues united through intramolecular hydrogen bonds O-H…O into a pseudomacrocyclic system. The neutral molecules 3-CONH₂-Py and 4-COOC₂H₅-Py are coordinated to the Fe²⁺ ion through the N atom of the heterocycle. Structure I is layered and structure II is molecular. Intermolecular interactions N-H…O are responsible for the formation of layers in crystal structure I.     

Synthesis,structure and thermal decomposition of [Ni(NH<Subscript>3</Subscript>)<Subscript>6</Subscript>][VO(O<Subscript>2</Subscript>)<Subscript>2</Subscript>(NH<Subscript>3</Subscript>)]<Subscript>2</Subscript>

The compound [Ni(NH₃)₆][VO(O₂)₂(NH₃)]₂ was prepared and characterized by elemental analysis and vibrational spectra. The single crystal X-ray study revealed that the structure consists of [Ni(NH₃)₆]²⁺ and [VO(O₂)₂(NH₃)]⁻ ions. As a result of weak interionic interactions V′···O_p (O_p-peroxo oxygen), ([VO(O₂)₂(NH₃)]⁻)₂ dimers are formed in the solid-state. The thermal decomposition of [Ni(NH₃)₆][VO(O₂)₂(NH₃)]₂ is a multi-step process with overlapped individual steps; no defined intermediates were obtained. The final solid products of thermal decomposition up to 600°C were Ni₂V₂O₇ and V₂O₅.     

Ionothermal syntheses of two new 2D metal-organic frameworks: (EMIM)<Subscript>2</Subscript>[M(Pydc)<Subscript>2</Subscript>] (M = Co,Zn)

Two new coordination polymers, (EMIM)₂[M(Pydc)₂] (M is Co, Zn; EMIM is 1-ethyl-3-methylimidazolium; H₂Pydc is 2,5-pyridinedicarboxylic acid), have been synthesized through the reaction of cobalt or zinc nitrate with H₂Pydc in the ionic liquid medium. The structures exhibit a two-dimensional 4.4-network with the imidazolium cations, acting as charge compensating agent, located between the layers of the coordination anion polymeric frameworks. The article is published in the original.     

Synthesis of nonequilibrium Ir<Subscript>x</Subscript>Re<Subscript>1-x</Subscript> solid solutions. Crystal structure of [Ir(NH<Subscript>3</Subscript>)<Subscript>5</Subscript>Cl]<Subscript>2</Subscript>[ReCl<Subscript>6</Subscript>]Cl<Subscript>2</Subscript>

Synthesis of five binary complex salts with an [Ir(NH₃)₅Cl]²⁺ complex cation is described. The counterions are [ReCl₆]^2–, [IrCl₆]^2–, [ReBr₆]^2–, and Cl^–. A polycrystal X-ray diffraction study has been performed for [Ir(NH₃)₅Cl]₂[ReCl₆]Cl₂, and its crystal structure has been determined. A series of Ir _x Re_1–x phases (0.5 x > 1) were obtained by reductive thermolysis. For the Ir-Re system, the history of the V/Z(x) dependence has been refined.Original Russian Text Copyright © 2004 by S. A. Gromilov, S. V. Korenev, I. V. Korolkov, K. V. Yusenko, and I. A. BaidinaTranslated from Zhurnal Strukturnoi Khimii, Vol. 45, No. 3, pp. 508–515, May–June 2004.