Growth and Characterisation of Gel-grown Lead(II)Chloride and Lead(II)Bromide Single Crystals

Single crystals of pure and doped lead(II)chloride and lead(II)bromide were grown by gel technique employing a modified two-stage chemical reaction. Methods to minimise the predomination of needle morphology during the growth of these crystals have been investigated and the results are discussed. The grown crystals were characterised by optical transmission spectrum. Undoped and monovalent cation (K⁺, Na⁺, Cu⁺, Ag⁺ and Hg⁺) doped crystals of PbCl₂ and PbBr₂ were subjected to d.c. electrical conductivity studies. Using the log σT versus T⁻¹ plot, the activation energies for the migration of anion vacancies in lead(II)halides are calculated. They are found to be less for the doped crystals than those of undoped ones.     

Synthesis and crystal structure of <Emphasis Type="Italic">catena</Emphasis>-bis(nicotinamide)aqua(μ-phthalato)copper(II) hemihydrate

The copper(II) phthalate complex with nicotinamide [CuL ₂(μ-Pht)(H₂O)] · 0.5H₂O(I) (where L is nicotinamide and Pht ^2? is an anion of phthalic acid) is synthesized and investigated using IR spectroscopy and X-ray diffraction. The crystals of compound I are monoclinic, a = 13.368(2) Å, b = 7.891(3) Å, c = 20.480(2) Å, β = 108.69(2)°, Z = 4, and space group P2₁/c. The structural units of crystal I are linear chains formed by bridging phthalate anions and crystallization water molecules. The copper atom is coordinated by two pyridine nitrogen atoms of two nicotinamide ligands (Cu-N, 2.001 and 2.045 Å), two oxygen atoms of different phthalate anions (Cu-O, 1.964 and 2.235 Å), and the oxygen atom of the H₂ O molecule (Cu-O, 2.014 Å). The coordination polyhedron of the copper atom is completed to an elongated (4 + 1 + 1) tetragonal bipyramid by the second (chelating) oxygen atom of the carboxyl group (Cu-O, 2.587 Å), which is one of the anions of phthalic acid. The linear polymer molecules are joined into complex macromolecular dimers with the closest internal contacts of the specific type. The macromolecular dimers are the main supramolecular ensembles of the crystal structure.     

Synthesis and Crystal Structure of 2,13-Bis(acetamido)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0<Superscript>1.18</Superscript>,0<Superscript>7.12</Superscript>]docosane Tetrachlorocobalt(II)dihydrate

Abstract The novel ionic compound [H₂bdtd][CoCl₄] · 2H₂O (1) was prepared by the reaction between CoCl₂ and 2,13-bis(acetamido)-3,14-dimethyl-2,6,13,17-tetraazatricyclo[14,4,0^1.18,0^7.12]docosane (bdtd) in adjusted to pH 3.0 by 1.0 M HCl and structurally characterized. The crystals are monoclinic C2/c with a = 18.7777(9), b = 9.7356(4), c = 20.0884(9) ?, β = 109.6340(10)°, V = 3458.9(3) ?³, Z = 4. The dication H₂bdtd occupies a special position about an inversion center. The cobalt(II) atom in the anion is in a distorted tetrahedral environment with four chloride ligands. The crystal structure is stabilized by a variety of hydrogen-bonding contacts involving the dication, chloride anions and solvent water molecules. Cyclic voltammetry of [CoCl₄]²⁻ anion in 1 undergoes irreversible one-electron reduction to the Co^II/Co^I. Graphical abstract The crystal structure of the ionic compound [H₂bdtd][CoCl₄] · 2H₂O (1) consists of [H₂bdtd]²⁺ cation, [CoCl₄]²⁻ anion and water molecules joined together by ionic interaction and hydrogen bonds. Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users.     

Molecular iodine catenation in the anionic chains [Pd2I6(I2)]2–

In the easily accessible salt [(H₅O₂)(db24c8)]₂[Pd₂I₆(I₂)], iodine molecules are catenated in linear anionic chains [^…I₂PdI₂PdI₂^…I–I^…]^2– which are separated by bulky cations consisting of two (H₅O₂)⁺ cations sequestered in dibenzo‐24‐crown‐8 (db24c8) molecules. The new compound is obtained as black single crystals (triclinic, P1, a = 1001.8(2), b = 1185.8(2), c = 1503.7(3) pm, α = 102.97(1), β = 107.65(1), γ = 90.85(1)°, V = 1652.3(5) 10⁶·pm³, Z = 1) from a moist 1:1 dichloromethane/ethanol solution of PdCl₂, iodine and db24c8. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Preparation,properties, and crystal structure of bis(acetylcholine)tetrabromodioxouranium(VI)

The compound bis(acetylcholine)tetrabromodioxouranium(VI), [C₇H₁₆-NO₂]₂ UO₂ Br₄, has been prepared and its physicochemical properties studied. No influence of the uranyl-bromide system on the muscarinic conformation of acetylcholine in the adduct was inferred on the basis of biological activity measurements. This lack of effect on the acetylcholine molecule by [UO₂Br₄]^2– anion is confirmed by X-ray structure determination. The crystals are orthorhombic, space groupPnma,Z = 4,a =13.60(2),b = 20.94(3),c = 9.22(2) Å. The conventional discrepancy index is 0.087 for 1822 diffractometer data. Some disorder is observed in the acetylcholine molecule.Abbreviations AcCh Acetylcholine - [AcCh]₂UO₂Br₄ bis(acetylcholine)tetrabromodioxouranium(VI) - AcChE Acetylcholinesterase     

Air-stable liquid clathrates. 1. Crystal structure of [NBu4][Br3] and reactivity of the [NBu4][Br3]·5 C6H6 liquid clathrate

[NBu₄][Br₃] interacts with C₆H₆ to form an air-stable liquid clathrate. The tribromide anion reacts with phenol to give para-bromophenol in>95% yield. The HBr which is generated in the reaction combines with the Br^– anion to form [Br-H-Br]^–. The latter forms the basis for a new liquid clathrate, [NBu₄][Br-H-Br]·n C₆H₆. The parent salt, [NBu₄][Br₃], crystallizes in the monoclinic space group C2/c witha=12.983(5),b=10.380(7),c=16.222(6) Å,=93.93(3)°, andD _c =1.47 g cm^–3 forZ=4. The final R value is 0.068 based on 787 observed reflections.     

Imidazolium based ionic liquid crystals: structure,photophysical and thermal behaviour of [Cnmim]Br·xH2O (n = 12, 14; x=0, 1)

The long chain imidazolium halides [C_nmim]Br·xH₂O (n = 10, 12; x = 0, 1) have been synthesized and their structural and thermal behaviour together with their photophysical properties characterized. X‐ray structure analyses of the monohydrates ([C₁₂mim]Br·H₂O: triclinic, P1, no. 2, Z = 2, Pearson code aP112, a = 550.0(5) pm, b = 779.4(5) pm, c = 2296.1(5) pm, α = 81.89(5)°, β = 83.76(5)°, γ = 78.102(5)°, 3523 unique reflections with I_o > 2σ(I_o), R₁ = 0.0263, wR₂ = 0.0652, GooF = 1.037, T = 263(2) K; [C₁₄mim]Br•H₂O: triclinic, P1, no. 2, Z = 12, Pearson code aP11, a = 549.86(8) pm, 782.09(13) pm, c = 2511.3(4) pm, α = 94.86(2)°, β = 94.39(2)°, γ = 101.83(2)°, 2063 unique reflections with I_o > 2σ(I_o), R₁ = 0.0429, wR₂ = 0.0690, GooF = 0.770, T = 293(2) K) show for both compounds similar bilayered structures. Sheets composed of hydrophilic structure regions constituted by positively charged imidazolium head groups, bromide anions and hydrogen bonded water alternate with hydrophobic areas formed by interdigitated long alkyl chains belonging to imidazolium cations with different orientation. Combined differential scanning calorimetry and polarizing optical microscopy shows that the monohydrates as well as the anhydrous imidazolium salts are thermotropic liquid crystals which adopt smectic mesophases. The mesophase region is larger in case of the monohydrates when compared to the anhydrous compounds indicating that water obviously stabilizes the mesophase. All compounds show an intense whitish photoluminescence with short lived (¹π←¹π*) and long lived (¹π←³π*) transitions. (© 2008 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

Crystal and molecular structure of 1,4-S,S′-bis-isothiosemicarbazidebutane dihydrobromide

The synthesis and crystal structure of 1,4-S,S-isothiosemicarbazidebutane dihydrobromide have been presented. The crystals are monoclinic:P2₁/n, a=7.9910(10),b=10.979(2),c=8.9240(10)Å, =111.450(10)°,Z=2, room temp. The structure was solved by direct methods. and refined to R=0.0297 for 846 reflections. The title compound consists of the centrosymmetric [C₆H₁₈N₆S₂]²⁺ dication and two Br^– anions. Intramolecular N–H...N and intermolecular N–H...Br hydrogen bonds stabilizetrans conformation of the thiosemicarbazide moiety.     

Synthesis and crystal structure of a silver(I) complex with dithioether ligand

The reaction of the dithioether ligand, 2,3-bis(5-methyl-1,3,4-thiadiazole-2-thiomethyl) quinoxaline (L) with AgBF₄, leads to the formation of a novel complex {[AgL](BF₄)}_∞ 1, which has been characterized by single-crystal X-ray diffraction analysis: monoclinic, space group C2/c, with a = 20.316(7) ?, b = 12.401(4) ?, c = 18.039(6) ?, β = 108.404(6)° and V = 4312(3) ?³. The crystal structure of the complex consists of 1D {[AgL]⁺}_∞ cation chain and BF₄ ⁻ anions. In 1, the coordination geometry of Ag^I center can be best described as trigonal planar coordinated by three N from two distinct L ligands. The ligand is polydentate with one end adopting a bidentate conformation to chelate an Ag^I atom and the other end monodentate to bridge another Ag^I resulting in an infinite chain along b axis. There exist Ag⋯N weak coordination, π–π stacking and F⋯S weak interactions in the complex, and these weak interactions link the 1D complex into 3D supramolecular structure and further stabilize the crystal structure in the solid state.     

Crystal structure of complexes of bivalent Co,Ni, and Cd with anions of benzoic and 2-(acetylamino)-5-nitrobenzoic acids

The structure of three complexes of bivalent metals (cobalt, nickel, and cadmium) with anions of benzoic (HL ¹) and 2-(acetylamino)-5-nitrobenzoic (HL ²) acids, namely, [Co₂¹ (H₂O)₂(μ-C₄H₄N₂)] _n (I), [NiL²(H₂O)₅]L² · 2H₂O (II), and [Cd(μ-L ²)₂(H₂O)₂] _n · 2nH₂O (III), is determined. In chainlike structure I, cobalt atoms are connected by bridging pyrazine molecules; structure II contains isolated complexes. In structure III, centrosymmetric (CdOCO)₂ cycles and polymeric ribbons are formed due to the coordination of the carboxylate group of the L ² ligand to two cadmium atoms.     

One-dimensional chain structure based on bifurcated hydrogen bonding

The structure of complex [PyH][Ni(mnt)₂], as determined by X-ray single crystal analysis, consists of pyridinium cations and [Ni(mnt)₂]^– anions. Crystallographic data for the complex: monoclinic P2₁/c, a = 16.5430(18) Å, b = 6.3847(9) Å, c = 17.430(2) Å, = 118.040(7)°, V = 1625.4(3) ų, Z = 4. The [Ni(mnt)₂]^– anion is not a planar and the CN groups bend away from the S₄ plane. The interactions between anions and cations via the formation of bifurcated N–H···NC hydrogen bonds give rise to an 1D zigzag chain of alternating cations and anions.     

Synthesis and Crystal Structure of the Salt [PPN+]2[Cu2I2Cl2]2−

Abstract The synthesis of the PPN (PPN=Ph₃P=N=PPh₃) salt of di-μ-iodo-dichlorocuprate (I) anion [Cu₂I₂Cl₂]²⁻ is described and the crystal and molecular structures of this compound are reported. It was found that the compound has the formula [PPN]₂[Cu₂I₂Cl₂]_0.7[Cu₂I₄]_0.3 (3). Compound 3 crystallizes in an orthorhombic crystal system, space group Pbca, with a = 19.654(3), b = 16.130(2), c = 20.108(3) ?, V = 6374.3(16) ?³ and Z = 4. The crystal contains 70% [Cu₂I₂Cl₂]²⁻ anions and 30% [Cu₂I₄]²⁻ anions. This was also confirmed by MSES spectroscopy. The anion [Cu₂I₂Cl₂]²⁻ is planar and the Cu atoms have a trigonal planar configuration. Graphical abstract Synthesis and Crystal Structure of the Salt [PPN ⁺ ] ₂ [Cu ₂ I ₂ Cl ₂ ] ²⁻ Andrey A. Yakovenko, Tatiana V. Timofeeva and Mikhail Yu. Antipin The title compound was synthesized and structurally investigated. The crystal contains 70% [Cu₂I₂Cl₂]²⁻ anions and 30% [Cu₂I₄]²⁻ anions. This was confirmed by MS ES spectroscopy.      

Molecular structure and spectroscopic characterization of tetrakis (2,5-diamino-1,3,4-thiadiazolium) decabromodibismuthate(III)

The title compound [C₂H₅N₄S]₄[Bi₂Br₁₀]; [HL]₄[Bi₂Br₁₀] (L=2,5-diamino-1,3,4-thiadiazole) was prepared and characterized by means of X-ray, and IR measurements. The structure was solved by the heavy-atom method, and least-squares refinement of structural parameters led to a conventionalR factor of 0.036 (R _w =0.032) for 2425 independent reflections. The crystal consists of a condensed [Bi₂Br₁₀]^4– anion and four HL⁺ cations. The anion has three bromine atoms involved in hydrogen bonds with N-bonded H atoms; the nonprotonated nitrogen atom of the cation is involved in hydrogen bonds too. The metal atoms have distorted octahedral geometry.     

Dependence of positron capture rate on dislocation density in solid solutions of KCl—KBr

Generally well-annealed alkali halide crystals exhibit three lifetime components. τ₁ arises due to annihilation with anion and τ₂ due to Bloch Ps. The origin of τ₃ is not well understood. Positron lifetime and etching techniques have been performed on solid solutions of KCl_100−xBr_x with mole % of x = 0.0, 15, 30, 37, 50, 70, and 100. The positron lifetime spectra have been analysed to resolve into three components. The positron capture rate K₃ for the longest lived component and the dislocation density shows a non-linear variation with composition. The positron capture rate varies linearly with the dislocation density of the samples. The origin of τ₃ is identified as due to positronium formation in the dislocations present in the samples. The trapping probability per dislocation has been estimated to be 2.2 × 10⁻¹²/s.     

Molecular Association of Almotriptan with Oxalate and Terephthalate Anions

Abstract  

Crystal structures of anti-migraine drug almotriptan were crystallized with oxalic acid (I) and with terephthalic acid (II) and their crystal structures and molecular associations were determined using X-ray diffraction methods. Crystals of both (I) and (II) are monoclinic, space group P2₁/c, with a = 5.6270(4) ?, b = 27.6419(19) ?, c = 13.6228(9) ?, β = 93.057(1)°, V = 2115.9(3) ?³, Z = 4 (I) and a = 13.3756(15) ?, b = 15.6065(17) ?, c = 10.7238(12) ?, β = 98.017(2)°, V = 2216.7(4) ?³, Z = 4 (II). In almotriptan oxalate {systematic name: N,N-dimethyl-2-[5-(pyrrolidin-1-ylsulfonyl-methyl)-1H-indol-3-yl]-ethanaminium semioxalate}, C₁₇H₂₆N₃O₂S⁺, C₂HO₄ ⁻, (I) and in almotriptan hemi terephthalate hydrate {systematic name: N,N-dimethyl-2-[5-(pyrrolidin-1-ylsulfonyl-methyl)-1H-indol-3-yl]-ethanaminium hemi terephthalate monohydrate}, C₁₇H₂₆N₃O₂S⁺, 0.5(C₈H₄O₄ ²⁻), H₂O, (II), both the almotriptan cations form a trimer with the corresponding anions via N–H···O hydrogen bonds. In (I), the oxalate salt is monoprotonated and in (II), the terephthalic acid is located across the inversion centre and exists as doubly protonated anion. In (I), the cation and anion are interlinked by the N–H···O and O–H···O hydrogen bonds into continuous two-dimensional layers generate an R₆⁶(34) hydrogen-bonded motif tetramers running parallel to the (0 0 1) plane. In (II), the cation and water form a centrosymmetric tetramer of R₄⁴(22) hydrogen-bonded motif via N–H···O and O–H···O hydrogen bonds and further cross-linked by centrosymmetric anions to form an infinite three-dimensional supramolecular hydrogen-bonded networks.     

The Investigation of Relation Between the Transition Temperature and the Unit Cell Volume in (K1-xCsx)2ZnCl4 Mixed Crystals

The relation between the phase transition temperature and unit cell volume in the (K_1-xCs_x)₂ZnCl₄ mixed crystals was studied. The phase transition temperature of A₂BX₄ family is dependent on the size of cation and anion (FABRY and PEREZ-MATO). That is, the transition temperature of crystal decreases with increasing unit cell volume. In this study we investigated this property of mixed crystals with the increasing mixture ratio. From the current study, we obtained the result that in the mixed crystals (K_1-xCs_x)₂ZnCl₄, the increase of x induces the increase of unit cell volume, so that T_I decreases with increasing unit cell volume. In order to determine the distribution of the substituted Cs⁺, using the near IR and UV spectrophotometer, we investigated both the band gap energy and the type of transition.     

Polyene ring attack in diag-CpRe(CO)2Br2 by hydride and cyclopentadiene displacement to furnish trans(Br)-[Re(CO)4Br2]? under CO: X-ray diffraction structure of trans(Br)-[Re(CO)4Br2][PPh4]

The reducing agent [Et₃BH][Li] reacts with diag-CpRe(CO)₂Br₂ in THF at –78C by polyene ring attack to give the anionic rhenium(I) compound [(⁴-C₅H₆)Re(CO)₂Br₂]^–. Monitoring the reaction by low-temperature IR spectroscopy has revealed that the reaction between diag-CpRe(CO)₂Br₂ and hydride is instantaneous and that the known compounds CpRe(CO)₂Br^– and CpRe(CO)₂Br(H) are not formed as the principal reduction products. The reduced compound [(⁴-C₅H₆)Re(CO)₂Br₂]^– is extremely temperature sensitive and decomposes upon warming to afford low yields of CpRe(CO)₃. We have explored the reactivity of the hydride reduction product with added CO and have isolated and structurally characterized the anionic tetracarbonyl compound trans(Br)-[Re(CO)₄Br₂]^– as the tetraphenylphosphonium salt. trans(Br)-[Re(CO)₄Br₂][PPh₄] crystallizes in the monoclinic space group C2/c, a = 16.908(2) Å, b = 7.1579(7) Å, c = 23.543(2) Å, = 96.144(9), V = 2832.9(5) ų, Z = 4, D_cacl = 1.870 g/cm³; R = 0.0419, R_w = 0.0450 for 1629 observed reflections with I > 3(I). The reaction between the product of hydride reduction and dppe is shown by IR and ³¹P NMR spectroscopies to produce mer-cis-BrRe(CO)₂(²-dppe)(¹-dppe).     

Crystallization of MIGe2(PO4)3 (MI – Na,K, Ag) from molten phosphate media

A number of NASICON‐related M^IGe₂(PO₄)₃ (M^I – Na, K, Ag) have been prepared using a high‐temperature solution method in the molten system M^I‐Ge‐P‐O (M^I – Na, K) based on the solubility data for GeO₂ at 1123 K for the Na‐P‐O system and 1173 K for the K‐P‐O one. The single crystals of AgGe₂(PO₄)₃ were obtained after crystallization of a melt with Ag/P = 1.4. It crystallizes in the trigonal system, space group R‐3, cell parameters a = 8.06340(1) Å, c = 21.8385(4) Å, Z = 6. The framework is built up from two GeO₆ units that are isolated from each other by PO₄ tetrahedra to form the main building block of the structure [Ge₂(PO₄)₃]⁻. Two types of silver cations M1 and M2 are found to have different coordination requirements shown by the bond valence sum calculations.     

Effects in B–doped KDP crystals irradiated with neutrons of large spectra energy

The results obtained for the r₆₃ electro‐optic coefficient of B‐doped and undoped KDP (KH₂PO₄) crystals irradiated with neutrons (including thermalized neutrons) produced by scattering of 30 Mev cyclotron protons on a target of Ta²⁰¹, are presented and compared to those obtained for non‐irradiated doped and undoped crystals. The B‐doped (H₃BO₃, Na₂B₄O₇ and Li₂B₄O₇) crystals were obtained by the conventional growth method by temperature decrease with 1 wt % dopant concentration in solution. The thermal neutron flux was around ϕ = 1. 10¹⁰ n/cm² s. Pulses of ∼15 μs long, in damped oscillatory mode (V= 8 kV, τ=1.95 μs) were used for the electro‐optic measurements. A Pockels cell, a photomultiplier, a He‐Ne laser (λ=632.8 nm, 5 mW, linearly polarized) and a Tk 720 A oscilloscope complete the experimental setup. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)     

A far infrared investigation of anionic species present in solution during the crystallization of a polynuclear bromocuprate(I) cluster containing three-coordinated copper (I)

Ethanolic solutions of tetrapropylammonium bromide and copper(I) bromide, from which bis(tetrapropylammonium) hexa--bromo-tetrahedro-tetracuprate(I), [N(C₃H₇)₄]₂[Cu₄Br₆], a bromocuprate(I) cluster comprised of three-coordinated copper(I), crystallizes have been shown, by means of far i.r. spectroscopy, to contain the centrosymmetric, monomeric [CuBr₂]^– anion as the major, and probably the sole, bromocuprate(I) species, ₃=323 cm^–1. Crystalline [N(C₃H₇)₄]₂[Cu₄Br₆], [N(CH₃)₄]₃[Cu₂Br₅] and [P(CH₃)₄]₂[CuBr₃], all of which contain anions in which copper(I) is three-coordinated, dissolve in nitro-methane to give solutions of the dibromocuprate(I) monomer. Variation of the coordination number of copper(I) in bromocuprates(I) crystallizing with symmetrically substituted quaternary ammonium and related unipositive cations is discussed in terms of dilution of the bromide ions by the cations, and a tentative mechanism for the formation of such compounds is proposed.Toward the end of the precipitation of [N(C₃H₇)₄]₂[Cu₄Br₆] from the ethanolic solution of tetrapropylammonium bromide and copper(I) bromide, a few crystals of a second bromocuprate(I) phase were obtained. This compound has been identified as tetrapropylammonium dibromocuprate(I), and its crystal structure determined from X-ray diffraction data. [N(C₃H₇)₄][CuBr₂] crystallizes in space groupP2/n, witha=13.010(15),b=7.577(5),c=8.858(4) Å,=91.09(7)° andZ=2. The anion is a monomer in which Cu-Br is 2.194(3) Å and Br-Cu-Br 178.4(1)°, copper(I) being situated on a twofold axis.