Crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo [8.8.8]hexacosane nitrate-hydrogen nitrate perchlorate semihydrate

An adduct of 2.2.2-cryptand with nitric and perchloric acids of the [H₂(Crypt-222)· 0.52H₂O]²⁺·ClO ₄ ^? ·NO ₃ ^? ·HNO₃ composition (I) is prepared and characterized by single crystal X-ray diffraction. The triclinic structure of I (space group \(P\overline 1 \), a = 10.176 Å, b = 11.272 Å, c = 12.870 Å, α = 78.61°, β = 76.62°, γ = 79.88°, Z = 2) is solved by a direct method and refined in the full-matrix anisotropic approximation to R = 0.062 for all 3642 measured independent reflections (CAD-4 automated diffractometer, λMoK _α). The structure of I contains a dication of 2.2.2-cryptand in the endo-endo conformation, two hydrogen atoms at the protonated N atoms are directed inside the cavity which also includes a water molecule with a site occupation factor of 0.52. Tetrahedral ClO ₄ ^? anion in I is disordered. In I, the H atom of the NO ₃ ^? ·HNO₃ dimer is split over two close positions with occupation factors of 0.33 and 0.67; this dimer is joined by a very strong single disordered hydrogen bond N-O-H?O = N between the molecule of nitric acid and its anion.     

Synthesis and crystal structure of hexa(nitrato-<Emphasis Type="Italic">O,O</Emphasis>′)dysprosium(III) Bis[4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane] nitrate dihydrate

A new complex salt 2[H₂(Crypt-222)]²⁺ · [Dy(NO₃)₆]^3? · NO ₃ ^? · 2H₂O is synthesized, and its crystal structure is studied by X-ray diffraction analysis (space group R \(\bar 3\), a = 11.445 Å, c = 38.981 Å, Z = 3; direct method, full-matrix least-squares method in the anisotropic approximation, R = 0.027 for 3555 independent reflections; CAD4 automated diffractometer, λMoK _α radiation). The [Dy(NO₃)₆]^3? anion and 2.2.2-cryptand dication lie on axis \(\bar 3\). The [Dy(NO₃)₆]^3? ligand in the [Dy(NO₃)₆]^3? anion is disordered. The Dy³⁺ cation has slightly distorted octahedral coordination with all six split vertices at the O atoms of the six symmetrically equivalent disordered NO ₃ ^? ligands.     

4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane Penta(nitrato)lanthanate(III): Synthesis and Crystal Structure

A new complex salt, 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane penta(nitrato)lanthanate(III) (H₂(Crypt-222)]²⁺ · [La(NO₃)₅]^2?), is synthesized. Its crystal structure is studied using X-ray diffraction analysis (space group Pbcm, a = 9.517 Å, b = 13.358 Å, c = 24.585 Å, Z = 4; direct method, full-matrix least-squares in the anisotropic approximation, R = 0.039 for 4650 measured independent reflections). The [La(NO₃)₅]^2? complex anion lies on the m plane, and the 2 axis passes through the 2.2.2-cryptand dication with two protonated nitrogen atoms. The coordination polyhedron of the La³⁺ cation (coordination number 11) is a distorted octahedron with five bifurcated vertices, each containing two O atoms from the same NO ₃ ^? . ligand. The [La(NO₃)₅]^2? anions are joined into infinite polymer chains along the y axis through the NO ₃ ^? bridging ligand.     

(18-Crown-6)(hydrogennitrato)potassium: Synthesis and crystal structure

A new complex, [K(18-crown-6)(NO₃)(HNO₃)] (I), is synthesized, and its crystal structure is studied using X-ray diffraction analysis: space group P \(\bar 1\), a = 8.253 Å, b = 9.277 Å, c = 13.903 Å, α = 95.89°, β = 104.30°, γ = 91.89°, Z = 2. The triclinic structure of compound I was solved by a direct method and refined by the full-matrix least-squares method in the anisotropic approximation to R = 0.059 for all 3573 independent reflections (CAD4 automated diffractometer, γMoK _α radiation). The structure of compound I contains two independent halves of two centrosymmetric complex molecules with different coordination modes of the K⁺ cations. Two NO ₃ ^? and HNO₃ ligands are randomly disordered relative to the symmetry center and are presented by two average independent H_0.5N ₃ ^1/2? , ligands, which are also orientationally disordered.     

Disordered crystal structure of 4,7,13,16,21,24-hexaoxa-1-aza-10-azoniabicyclo[8.8.8]hexacosane perchlorate monohydrate

The disordered crystal structure of 4,7,13,16,21,24-hexaoxa-1-aza-10-azoniabicyclo[8.8.8]-hexacosane perchlorate monohydrate, [H(Crypt-222)·H₂O]⁺·ClO ₄ ^? (I), has been determined by XRD. The triclinic structure of I (space group \(P\overline 1 \), a = 9.748 Å, b = 10.570 Å, c = 13.820 Å; α = 109.40°, β = 109.75°, γ = 93.04°, Z = 2) was solved by direct methods and refined by full-matrix least-squares in the anisotropic approximation to R = 0.072 over all 3675 independent reflections collected (CAD-4 automatic diffractometer, λCuK_α). This compound is the first crystal salt containing the 2.2.2-cryptand cation with one protonated nitrogen atom that was synthesized and structurally investigated.     

Synthesis and crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane sulfate tetrahydrate

A hydrated salt of 2.2.2-cryptand and sulfuric acid [H₂(Crypt-222)]²⁺ · SO ₄ ^2? · 4H₂O(I) was prepared and studied by X-ray diffraction. The structure of I (space group C2/c, a = 22.823, b = 9.610, c = 26.150 Å, β = 107.71°, Z = 8) was solved by the direct method and refined by full-matrix least-squares in the anisotropic approximation to R = 0.056 for 4032 independent reflections (CAD4 automated diffractometer, λMoK _α radiation). In the structure of I, the 2.2.2-cryptand dication (with approximate C ₂ symmetry) has a rare exo-exo conformation where two H atoms at two N atoms are directed away from the cavity. The tetrahedral SO ₄ ^2? anion is disordered over two orientations. In two water molecules, the H atoms are disordered, while in the other two water molecules all atoms are disordered. The crystal structure of I has an extensive three-dimensional system of ion-ion (intermolecular) hydrogen bonds in which infinite chains of alternating SO ₄ ^2? anions and 2.2.2-dications can be distinguished.     

Stability of diammine and chloroammine gold(I) complexes in aqueous solution

The substitution equilibria AuCl ₂ ^? + iNH ₄ ⁺ = Au(NH₃)_iCl_{2 ? i} + iCl^? + iH⁺, β _i ^* . were studied pH-metrically at 25°C and I = 1 mol/L (NaCl) in aqueous solution. It was found that logβ ₁ ^* = ?5.10±0.15 and logβ ₂ ^* = ?10.25±0.10. For equilibrium AuNH₃Cl_solid = AuNH₃Cl, log K _s = ?3.1±0.3. Taking into account the protonation constants of ammonia (log K _H = 9.40), the obtained results show that for equilibria AuCl ₂ ^? + iNH₃ = Au(NH₃)_iCl_{2 ? i} + iCl^?, logβ₁ = 4.3±0.2, and logβ₂ = 8.55±0.15. The standard potentials E ₀ ^1/0 of AuNH₃Cl⁰ and Au(NH₃) ₂ ⁺ species are equal to 0.90±0.02 and 0.64±0.01 V, respectively.     

Theoretical study of oxoborate complexes with MO<Stack><Subscript>4</Subscript><Superscript><Emphasis Type="Italic">n</Emphasis>−</Superscript></Stack> tetraoxo anions in the inner and outer spheres of the B<Subscript>20</Subscript>O<Subscript>30</Subscript> cluster

The energies and structural and spectroscopic characteristics of endohedral (MO₄©B₂₀O ₃₀ ^n? ) and exohedral (MO₄ · B₂₀O ₃₀ ^n? ) isomers of oxoborate complexes with MO ₄ ^n? tetraoxo anions with 32 valence electrons located in the inner and outer spheres of the B₂₀O₃₀ cluster have been calculated by the density functional theory method (B3LYP). It has been demonstrated that, among the endohedral MO₄©B₂₀O ₃₀ ^n? clusters with strong multiply charged anions (VO ₄ ^3? , CrO ₄ ^2? , PO ₄ ^3? , SO ₄ ^2? , AsO ₄ ^3? , SeO ₄ ^2? , etc.), the isomer in which a “guest” tetrahedron MO₄ is located at the center of the B₂₀O₃₀ cage and bonded to it through internal oxygen bridges M-O*-B is the most favorable one. Among the exohedral analogues MO₄ · B₂₀O ₃₀ ^n? , two most favorable isomers contain the “capping” MO₄ tetrahedron bonded to the B₂₀O₃₀ cage through two and three external M-O-B bridges. For the complexes with doubly charged SO ₄ ^2? and SeO ₄ ^2? anions, the third exohedral isomer in which the sulfite or selenite group MO₃ is bidentately coordinated to the oxidized B₂₀O₂₉(OO) cage with one peroxide bridge turns out to be close in energy to the above two isomers. For the systems with high negative charge n, the exohedral isomers are much more favorable than the endohedral isomer; however, with decreasing charge, the difference in energy between them decreases to ~10–18 kcal/mol, so that the exo–endo transition between them can require moderate energy inputs. For the endohedral complexes with singly charged ClO ₄ ^? and BrO ₄ ^? anions, two isomers with close energies are preferable in which the central atoms of the guest tetrahedra are reduced to the state of singly charged ions, while the oxoborate cage is oxidized to B₂₀O₂₆(OO)₄ with four peroxide groups B-O-O-B and retains its closed (closo) structure. In the most favorable isomer of the complexes with multicharged ortho-anions BO ₄ ^5? , CO ₄ ^4? , and NO ₄ ^3? , the outersphere anion is reduced to, respectively, borate, carbonate, and nitrate bidentately coordinated to the oxidized B₂₀O₂₉(O)₂ cage with an open structure and two strongly elongated terminal B-O bonds. The results are compared with the data of previous calculations of endohedral and exohedral vanadate complexes MO₄©V₂₀O ₅₀ ^n? and MO₄ · V₂₀O ₅₀ ^n? with the same guest anions MO ₄ ^n? .     

Degradation of trichloroethylene in aqueous solution by persulfate activated with Fe(III)–EDDS complex

In this study, an environmentally friendly complexing agent, S,S′-ethylenediamine-N,N′-disuccinic acid (EDDS), was applied in Fe(III)-mediated activation of persulfate (PS), and the degradation performance of trichloroethylene (TCE) was investigated. The effects of PS concentration, Fe(III)/EDDS molar ratio, and inorganic anions on TCE degradation were evaluated, and the generated reactive oxygen species responsible for TCE removal were identified. The results showed that nearly complete TCE degradation was achieved with PS of 15.0 mM and a molar ratio of Fe(III)/EDDS of 4:1. An increase in PS concentration or Fe(III)/EDDS molar ratio to a certain value resulted in enhanced TCE degradation. All of the anions (Cl^?, HCO₃ ^?, SO₄ ^2?, and NO ₃ ^? ) at tested concentrations had negative effects on TCE removal. In addition, investigations using radical probe compounds and radical scavengers revealed that sulfate radicals (SO ₄ ^·? ), hydroxyl radicals (^·OH), and superoxide radical anions (O ₂ ^·? ) were all generated in the Fe(III)–EDDS/PS system, and ^·OH was the primary radical responsible for TCE degradation. In conclusion, the Fe(III)–EDDS-activated PS process is a promising technique for TCE-contaminated groundwater remediation.     

Investigation of Chloride Ion Substitution Equilibria in AuCl<Stack><Subscript>4</Subscript><Superscript>−</Superscript></Stack> with Ethylenediamine and 1,3-Diaminopropane Using Capillary Zone Electrophoresis

Substitution of chloride ions in AuCl ₄ ^? with ethylenediamine (en) and propylenediamine (tn) is studied by capillary zone electrophoresis at I = 0.05 M and T = 25°C. The substitution constants are determined: AuenCl ₂ ⁺ + en = Auen ₂ ³⁺ + 2Cl^–, logK₂ = 10.4; AuCl ₄ ^? + tn = AutnCl ₂ ⁺ + 2Cl^–, logK₁ = 16.1; AutnCl ₂ ⁺ + tn = Autn³⁺₂ + 2Cl^–, logK₂ = 12.0.     

Crystal structure of glycine phosphite C<Subscript>2</Subscript>H<Subscript>5</Subscript>NO<Subscript>2</Subscript>·H<Subscript>3</Subscript>PO<Subscript>3</Subscript>

Single crystal X-ray diffraction study of glycine phosphite C₂H₅NO₂·H₃PO₃ was performed (monoclinic, space group P2₁/c, a = 7.401(3) Å, b = 8.465(3) Å, c = 9.737(3) Å; β = 100.73(5)°, Z = 4). It has been found that one of hydrogen atoms is located at the centre of symmetry forming two strong hydrogen bonds to yield H₄P₂O ₆ ^?2 dimers, while another hydrogen atom is statistically disordered over two positions and organizes the dimers into an infinite corrugated chain. The ordering of this hydrogen atom position and/or displacement of the other one from the centre of symmetry will lead to the loss of symmetry centre and lowering of the point group symmetry from C_2h to piezo-active group C₂ or C _s .     

Thermal properties of dimethylgold(III) 8-hydroxyquinolinate and 8-mercaptoquinolinate

Dimethylgold(III) complexes with 8-hydroxyquinoline Me₂Au(Ox) (I) and 8-mercaptoquinoline Me₂Au(Tox) (II) were synthesized and studied. Complex II obtained for the first time was identified from the elemental analysis, IR, ¹H NMR, and mass spectrometry data. The thermal properties of complexes I, II in condensed state were investigated by thermography. The temperature dependences of the saturated vapor pressure over crystals were measured by the Knudsen effusion method with mass spectrometric recording of the gas phase composition and the thermodynamic characteristics of the sublimation process were determined: for I, log P[Torr] = (14.6 ± 0.3) ? (6.34 ± 0.10) × 10³/(T, K), Δ H _subl ^o = 121.2 ± 1.9 kJ^?1, Δ S _subl ^o = 224.1 ± 4.6 J mol^?1 K^?1 (the temperature interval under study 80–115°C); for II, log P [Torr] = (13.3 ± 0.2) ? (6.30 ± 0.09) × 10³/(T, K), Δ H _subl ^o = 120.5 ± 1.7 kJmol^?1, ΔS _subl ^o = 199.3 ± 3.0 J mol^?1 K^?1 (86–145°C).     

Crystal Structure and Properties of Levofloxacinium 2-Thiobarbiturate Trihydrate

The structure of levofloxacinium 2-thiobarbiturate trihydrate LevoH ₂ ⁺ Htba^–·3H₂O (I) (LevoH is levofloxacin, H₂tba is 2-thiobarbituric acid) is determined (CIF file CCDC No. 1547466); its thermal decomposition and IR spectrum are studied. The crystals of I are triclinic: a = 8.670(1) Å, b = 9.605(1) Å, c = 15.786(2) Å, α = 89.144(5)°, β = 88.279(5)°, γ = 76.068(5)°, V = 1275.4(3) ų, space group P1, Z = 2. The unit cell of I contains two LevoH ₂ ⁺ ions, two Htba^– ions, and six H₂O molecules. The absolute structure of the crystal and the configuration of the chiral center in a levofloxacin molecule S are determined. Experiments for generating the second optical harmonics gave a positive result. Intermolecular hydrogen bonds (HBs) N–H···O and O–H···O in I form a bilayer system along the ab diagonal with hydrophilic moieties within a layer and hydrophobic moieties directed outward. The structure is stabilized by multiple HBs and the π–π interaction between the Htba–and LevoH ₂ ⁺ ions and between the LevoH ₂ ⁺ ions.     

4,7,13,16,21,24-Hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane hydrogen phosphate octahydrate: Synthesis and crystal structure

A crystalline hydrated salt of the 2.2.2-cryptand and phosphoric acid, [H₂(Crypt-222)](HPO₄) · 8H₂O (I), is synthesized. Its crystal structure is studied using X-ray diffraction analysis (space group P2₁/n, a = 9.244 Å, b = 25.750 Å, c = 13.218 Å, β = 95.87°, Z = 4; direct method, full-matrix least-squares method in the anisotropic approximation to R = 0.055 for 4622 reflections, CAD4 automated diffractometer, λMoK _α radiation). The structure contains the 2.2.2-cryptand dication with the rare exo-exo, conformation with two H atoms at two N atoms directed outside from the cavity. A P atom of the HPO ₄ ^2? anion has a considerably distorted tetrahedral coordination. The crystal of compound I contains a branched infinite three-dimensional system of intermolecular (interionic) hydrogen bonds.     

Crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH<Subscript>2</Subscript>NHC(O)NH<Subscript>2</Subscript>)<Subscript>2</Subscript>](NO<Subscript>3</Subscript>)<Subscript>2</Subscript>

The crystal structure of bis(semicarbazido)copper(II) nitrate [Cu(NH₂NHC(O)NH₂)₂](NO₃)₂ has been studied by X-ray diffraction. Monoclinic crystals, a = 6.835(2) Å, b = 7.733(2) Å, c = 10.320(3) Å, β = 105.701(3)°, V = 525.1(2) ų, space group P2₁/c, Z = 2, d _msd = 2.136 g/cm³, μ(MoK _α) = 2.143 mm⁻¹. The structure was solved with the program for automatic analysis of Patterson’s function and refined by full-matrix least squares in an anisotropic approximation for all non-hydrogen atoms using 753 independent reflections; R ₁ = 0.0203. The square environment of the Cu atom is formed from the amino nitrogen atoms of the hydrazine fragments and the C=O oxygen atoms of the two semicarbazide bidentate molecules (Cu-N 1.928 Å, Cu-O 1.999 Å). The axial positions are occupied by the O atoms of the NO ₃ ⁻ outer-spheric anions (Cu-O 2.505 Å). In the structure, the complex cations and the NO ₃ ⁻ anions are linked into a framework by N-H...O type hydrogen bonds. Original Russian Text Copyright ? 2007 by G. V. Romanenko, Z. A. Savelieva, and S. V. Larionov __________ Translated from Zhurnal Strukturnoi Khimii, Vol. 48, No. 2, pp. 370–373, March–April, 2007.     

Dissolution kinetics of silver metal nanoparticles in their reaction with nitric acid in an reverse micelle solution of AOT

The dissolution of silver nanoparticles in their reaction with aqueous HNO₃ solubilized to an reverse micelle solution of sodium bis(2-ethylhexyl)sulfosuccinate in decane is studied spectrophotometrically. A physicochemical model is advanced for quantifying the process kinetics on th basis of the following autocatalytic scheme: Ag⁰ + H⁺ + NO ₃ ^? → Ag⁺ + products (k ₁), and Ag⁰ + Ag⁺ + NO ₃ ^? → 2Ag⁺ + products (k ₂). The effective rate constant k ₂ decreases with decreasing solubilization capacity V _S/V _O (where V _S is the volume of the solubilized dispersed aqueous phase and V _O is the volume of the micelle solution); the solubilization capacity determines the size of the micelle cavities in which the reaction between Ag⁰ and HNO₃ occurs: k ₂ = 74 (V _S/V _O) · 100% ≈ 3.8%), 41 (2.9), and 35 (2.0) L/(mol s). The effective constant k ₁ is determined with a high uncertainty; the effect of V _S/V _O on k ₁ has the opposite tendency.     

Crystal structure of Cs[(UO<Subscript>2</Subscript>)<Subscript>2</Subscript>(C<Subscript>2</Subscript>O<Subscript>4</Subscript>)<Subscript>2</Subscript>(OH)] · H<Subscript>2</Subscript>O

Single crystals of Cs[(UO₂)₂(C₂O₄)₂(OH)] · H₂O were synthesized and structurally studied using X-ray diffraction. The compound crystallizes in monoclinic space group P2₁/m, Z = 2, with the unit cell parameters a = 5.5032(4) Å, b = 13.5577(8) Å, c = 9.5859(8) Å, β = 97.012(3)°, V = 709.86(9) ų, R = 0.0444. The main building units of crystals are [(UO₂)₂(C₂O₄)₂(OH)]^? layers of the A₂K ₂ ⁰² M² (A = UO ₂ ²⁺ , K⁰² = C₂O ₄ ^2? , and M² = OH^?) crystal-chemical family. Uranium-containing layers are linked into a three-dimensional framework via electrostatic interactions with outer-sphere cations and hydrogen bonds with water molecules.     

Field-induced π-polarization in barrelene derivatives: a computational study based on structural variation

Barrelene, H–C(CH=CH)₃C–H, is an unsaturated polycyclic hydrocarbon containing three isolated double bonds in a non-planar arrangement. We have studied the transmission of field effects through the barrelene framework by analyzing the small structural changes occurring in the phenyl group of many Ph–C(CH=CH)₃C–X molecules, where X is a variable substituent. Molecular geometries have been determined by quantum chemical calculations at the HF/6-31G* and B3LYP/6-311++G** levels of theory. Comparison with the results obtained for the corresponding saturated molecules, the bicyclo[2.2.2]octane derivatives Ph–C(CH₂–CH₂)₃C–X, reveals a small, but significant, field-induced π-polarization of the barrelene cage, especially when the remote substituent is a charged group. Additional evidence of π-polarization is obtained by comparing the electric dipole moments of the two sets of uncharged molecules. The structural variation of the barrelene cage caused by the variable substituent in Ph–C(CH=CH)₃C–X molecules has also been investigated. It is much larger than that of the phenyl group and depends primarily on the electronegativity of the substituent. Particularly pronounced is the concerted variation of the non-bonded distance between the bridgehead carbons of the cage, r(C···C) ₁ ^BARR , and the average of the three C–C–C angles at the cage carbon bonded to the variable substituent, α ₁ ^BARR . A scattergram of r(C···C) ₁ ^BARR versus the corresponding parameter for bicyclo[2.2.2]octane derivatives, r(C···C) ₁ ^BCO , shows that the variation of r(C···C) ₁ ^BARR becomes gradually less pronounced than that of r(C···C) ₁ ^BCO as the electronegativity of the substituent increases.     

Stability of gold(I) glycinate complexes in aqueous solution

The stepwise substitution equilibrium AuCl ₂ ^? +iX^?=AuCl_2?i X _i ^? +iCl^?, β_i, where X^? is the glycinate ion (H₂N-CH₂-COO^?), i = 1 or 2, at 25°C in an aqueous solution with I = 1.0 mol/L (NaCl) has been studied pH-metrically. The corresponding constants are logβ₁ = 3.60 ± 0.10, and logβ₂ = 6.2 ± 0.2.     

Disordered crystal structure of 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane <Emphasis Type="Italic">bis</Emphasis>(picrate) hydrate

For 4,7,13,16,21,24-hexaoxa-1,10-diazoniabicyclo[8.8.8]hexacosane bis(picrate) hydrate [H₂(Crypt-222)]²⁺·2Pic^?·1.19 H₂O (I), its disordered crystal structure has been determined by X-ray diffraction (XRD) analysis. The structure of I (space group \(P\bar 1\), a = 10.662 Å, b = 12.586 Å, c = 15.342 Å, α = 107.73°, β = 102.33°, γ = 90.49°, Z = 2) was solved by direct methods and refined by full-matrix least-squares in an anisotropic approximation to R = 0.111 for all 5000 independent reflections collected (CAD-4 automatic diffractometer, CAD-4, λMoK_α). The 2.2.2-cryptand dication is disordered and has two different conformations with probabilities of 66.7% and 33.7%. In addition to one independent water molecule, the cavity of the dication has a low-probability site of another water molecule, whose occupancy is 0.19. In the two independent picrate anions, some of their NO₂ groups are disordered over two orientations. The crystal structure of I has various interionic (intermolecular) and intracation hydrogen bonds.