Tetraethylammonium dihydrogenarsenate bis(arsenic acid) and 1,4‐diazoniabicyclo[2.2.2]octane bis(dihydrogenarsenate) arsenic acid: hydrogen‐bonded networks containing dihydrogenarsenate anions and neutral arsenic acid molecules

The title compounds, (C₈H₂₀N)[H₂AsO₄][H₃AsO₄]₂, (I), and (C₆H₁₄N₂)[H₂AsO₄]₂[H₃AsO₄], (II), are unusual salts containing organic cations, dihydrogenarsenate anions and neutral arsenic acid molecules. In (I), the dihydrogenarsenate anion lies across a twofold rotation axis in the space group C2/c, while the cation is disordered across a centre of inversion. The [H₂AsO₄]⁻ and H₃AsO₄ species interact by way of O—H...O hydrogen bonds, leading to sheets and a three‐dimensional network for (I) and (II), respectively.     

Three new acid M+ arsenates and phosphates with multiply protonated As/PO4 groups

The crystal structures of caesium dihydrogen arsenate(V) bis[trihydrogen arsenate(V)], Cs(H₂AsO₄)(H₃AsO₄)₂, ammonium dihydrogen arsenate(V) trihydrogen arsenate(V), NH₄(H₂AsO₄)(H₃AsO₄), and dilithium bis(dihydrogen phosphate), Li₂(H₂PO₄)₂, were solved from single‐crystal X‐ray diffraction data. NH₄(H₂AsO₄)(H₃AsO₄), which was hydrothermally synthesized (T = 493 K), is homeotypic with Rb(H₂AsO₄)(H₃AsO₄), while Cs(H₂AsO₄)(H₃AsO₄)₂ crystallizes in a novel structure type and Li₂(H₂PO₄)₂ represents a new polymorph of this composition. The Cs and Li compounds grew at room temperature from highly acidic aqueous solutions. Li₂(H₂PO₄)₂ forms a three‐dimensional (3D) framework of PO₄ tetrahedra sharing corners with Li₂O₆ dimers built of edge‐sharing LiO₄ groups, which is reinforced by hydrogen bonds. The two arsenate compounds are characterized by a 3D network of AsO₄ groups that are connected solely via multiple strong hydrogen bonds. A statistical evaluation of the As—O bond lengths in singly, doubly and triply protonated AsO₄ groups gave average values of 1.70 (2) Å for 199 As—OH bonds, 1.728 (19) Å for As—OH bonds in HAsO₄ groups, 1.714 (12) Å for As—OH bonds in H₂AsO₄ groups and 1.694 (16) Å for As—OH bonds in H₃AsO₄ groups, and a grand mean value of 1.667 (18) Å for As—O bonds to nonprotonated O atoms.     

Die Kristallstruktur von AgCu3Cu(AsO4)3 und ihre strukturellen Beziehungen zu AgCo3H2(AsO4)3 bzw. AgZn3H2(AsO4)3

Crystal Structure of AgCu₃Cu(AsO₄)₃ and its Structural Relations to AgCo₃H₂(AsO₄)₃ and AgZn₃H₂ (AsO₄)₃ The compound AgCu₃Cu(AsO₄)₃ was synthesized and investigated by X-rays. It crystallizes in the monoclinic space group C2/c with a = 1 212.7(2), b = 1 249.0(2), c = 727.8(1) pm, β = 117.94(1)°, Z = 4. The structure is closely related to the structures of AgCo₃H₂(AsO₄)₃ and AgZn₃H₂(AsO₄)₃. Only two hydrogen atoms are replaced by an additional copper atom forming a copper coordination square instead of two hydrogen bridges. The remaining copper atoms are sixfold coordinated with the generally observed Jahn-Teller distortion. Whereas in AgCo₃H₂(AsO₄)₃ and AgZn₃H₂(AsO₄)₃ silver has a (4+4) coordination, it is in this compound distinctly eightfold coordinated.     

Raman und infrarotspektroskopische Untersuchungen an Alkylderivaten der Arsensäure. III. Die Schwingungsspektren von Methan- und Äthanarsonsäure sowie von Natriumhydrogenmethanarsonat

RAMAN and IR-spectroscopic Investigation of Alkyl Derivatives of Arsenic Acid. III. The Vibrational Spectra of Methane and Ethanearsonic Acid and Sodium Hydrogenmethanearsonate. The RAMAN spectra of CH₃AsO₃H₂, C₂H₅AsO₃H₂ CH₃AsO₃HN₂. 3/2 H₂O (solid and in concentrated aqueous solution) and the IR spectra (400 -4000 cm^?1) of these solid acids – partially deuterated – and of the hydrogenarsonate are discussed. The very probable symmetry of these compounds is C_s. As the IR spectra show (two strong broad OH valence bands at 2820 and 2350 cm^?1; OH deformation frequency at 1220 cm^?1), rather strong H-bonds exist in these acid substances.     

Enzyme-catalysed Transformations of Compounds Containing the –CH2-AsO3H2 Group

Enzymes that act on substrates R–O–PO₃H₂ often work on substrate analogues R–O–AsO₃H₂; such substrates are unstable, since esters of H₃AsO₄ hydrolyse easily. They also form easily, so that an enzyme that acts on R–O–PO₃H₂ often acts on a mixture of R–OH and arsenate via an ester that forms at the active site. Similarly coenzyme analogues may be formed; for example, a stable and active aspartate aminotransferase forms from the apoenzyme with free pyridoxal and arsenate. Enzymes that convert R–O–PO₃H₂ into a diester often act on R–CH₂–AsO₃H₂, a stable substrate analogue; then the product is unstable and hydrolyses to re-form the analogue, giving a futile cycle. For example, RNA polymerase acquires exonuclease activity in the presence of H₂O₃P–CH₂–AsO₃H₂; adenylate kinase acquires ATPase activity in the presence of the arsonomethyl analogue of AMP. A recent observation is that HO–CH₂–CHOH–CH₂–CH₂–AsO₃H₂ is a good substrate for glycerol-3-phosphate dehydrogenase. The product is unstable and eliminates arsenite, sharing this ability with other 3-oxoalkylarsonates. Thus this enzyme–catalysed oxidation is a lethal synthesis, in view of the toxicity of arsenite. Another unusual biochemical reaction of an arsonic acid is seen in the ability of a bacterium to use arsonoacetate as its sole source of carbon and energy. In contrast with the elimination of arsenite by 3-oxoalylarsonic acids, 3-oxoalkylphosphonic acids, R–CO–CH₂–CH₂–PO₃H₂, are stable. 2-Oxoalkylphosphonic acids, R–CO–CH₂–PO₃H₂, however, are moderately unstable to hydrolysis, yielding phosphate and R–CO–CH₃. 2-Oxoalkylarsonic acids, R–CO–CH₂–AsO₃H₂, decompose in the same way, but much more readily, yielding arsenate. © 1997 by John Wiley & Sons, Ltd.     

Loss of activity by vanadium sulfuric acid catalysts under the action of arsenic(III) oxide vapor

Chemical processes leading to inactivation of vanadium sulfuric acid catalysts by arsenic(III) oxide vapor were studied. The interaction and solubility in the system VO(H₂AsO₄)₂-VOAsO₄-H₃AsO₄-H₂O and the composition of oxovanadium arsenate in a mixed oxidation state, used as a starting substance in synthesis of (V^IVO)(V^VO)₂(As₂O₇)₂, were examined.     

Dimethylphosphinato and dimethylarsinato complexes of Sb(III) and Bi(III) and their chemistry

Abstract  

The reaction of Me₂PO₂H and Me₂AsO₂H with SbCl₃, BiCl₃, and Bi(NO₃)₃·5H₂O gave the complexes Sb(Me₂PO₂)₃, Sb(Me₂AsO₂)₃, (Me₂PO₂)₂Bi-Cl, Bi(Me₂AsO₂)₃, (Me₂PO₂)₂Bi(NO₃), and (Me₂AsO₂)₂Bi(NO₃)·H₂O, respectively. The arsinato complexes did not react with the Lewis bases pyridine, Ph₃P, and Ph₃As in acetone. The compounds Sb(Me₂AsO₂)₃ and (Me₂AsO₂)₂Bi(NO₃)·H₂O reacted to a small extent with nicotinic acid in methanol but Bi(Me₂AsO₂)₃ gave (Me₂AsO₂-BiO) _x in good yields. (Me₂AsO₂)₂Bi(NO₃)·H₂O in methanol quantitatively rearranged to new complexes with the same composition, [(Me₂AsO₂)₂Bi(NO₃)·H₂O]′ and [(Me₂AsO₂)₂Bi(NO₃)·H₂O]″ in the presence of pyridine. With thiophenol in air, Sb(Me₂AsO₂)₃ gave PhSSPh and Me₂As-SPh (1:1 mol ratio), (Me₂AsO₂-SbO) _x and some Sb(Me₂AsO₂)₃ was reformed, Bi(Me₂AsO₂)₃ gave (Me₂AsO₂-BiO) _x , PhSSPh, and Me₂As-SPh (1:0.6 mol ratio), whereas (Me₂AsO₂)₂Bi(NO₃)·H₂O quantitatively gave PhSSPh, thus acting as a catalyst for the air oxidation of thiophenol.     

AgCo3H2(AsO4)3 und AgZn3H2(AsO4)3 Darstellung und Kristallstruktur Ein weiterer neuer Arsenat-Strukturtyp

AgCo₃H₂(AsO₄)₃ and AgZn₃H₂(AsO₄)₃. Preparation and Crystal Structure. Another New Structure Type of an Arsenate AgCo₃H₂(AsO₄)₃ ( 1 ) and AgZn₃H₂(AsO₄)₃ ( 2 ) were prepared by heating of As₂O₅, AgNO₃, CoSO₄ · 7H₂O, ZnSO₄ · 7H₂O, respectively, and water in a sealed tube at 300°C and investigated with X-rays. Both compounds are isotypic and crystallize in the monoclinic space group C2/c with 4 formula units per cell. The lattice parameters are ( 1 ): a = 1215.9(6), b = 1243.8(7), c = 678.2(3) pm, β = 113.16(3)° ( 2 ): a = 1216.9(2), b = 1249.5(3), c = 675.5(1) pm, β = 112.77(1)°. The structure contains chains of edge-shared CoO₆ or ZnO₆ octahedra, respectively, which are connected by AsO₄ tetrahedra and silver oxygen ribbons with square planar coordinated silver forming a framework. Based on the charge balances derived from the geometrical data and the IR spectra the occurence of hydrogen bonds is discussed.     

Effect of Sodium Hydroarsenate on the Kinetics of Reduction of Hydrogen Ions at Iron and on the Hydrogen Diffusion through a Steel Membrane from Aqueous and Ethylene Glycol Solutions of Hydrochloric Acid

Effect of arsenic compounds H₃AsO₄, H₂AsO₄ ^–, and HAsO₄ ^2– on the hydrogen overvoltage, the slow stage of discharge of hydronium ions on the Armco iron, and the hydrogen diffusion through a steel membrane from aqueous and ethylene glycol solutions of hydrochloric acid with a constant ionic strength of unity is considered.     

CsAl(H2AsO4)2(HAsO4): a new monoclinic protonated arsenate with decorated kröhnkite‐like chains

The crystal structure of hydro­thermally synthesized caesium aluminium bis­[dihydrogen arsenate(V)] hydrogen arsen­ate(V), CsAl(H₂AsO₄)₂(HAsO₄), was determined from single‐crystal X‐ray diffraction data collected at room temperature. The compound represents a new structure type that is characterized by decorated kröhnkite‐like [100] chains of corner‐sharing AlO₆ octa­hedra and AsO₄ tetra­hedra. Ten‐coordinated Cs atoms are situated between the chains, which are inter­connected by five different hydrogen bonds [O⋯O = 2.569 (4)–2.978 (4) Å]. All atoms are in general positions. CsAl(H₂AsO₄)₂(HAsO₄) is very closely related to CsGa(H_1.5AsO₄)₂(H₂AsO₄) and isotypic CsCr(H_1.5AsO₄)₂(H₂AsO₄).     

Vibrational spectroscopy,electrical characterization,nonlinear optical properties and DFT calculation of (NEt4)(H2AsO4)(H3AsO4)2

An organic-inorganic compound of tetraethylammonium dihydrogenarsenate bis(arsenic acid) salts of formula (NEt₄)(H₂AsO₄)(H₃AsO₄)₂, a potential new nonlinear optical material, was prepared by a slow evaporation technique and characterized by IR and Raman spectroscopy accomplished with DFT calculation and electrical-dielectrical measurements. The structure has been solved using direct method and refined by least-squares analysis. In this case, the structure consists of infinite parallel two-dimensional planes built of mutually H₂AsO₄^?, H₃AsO₄ tetrahedra connected by strong O–H?O hydrogen bonding giving birth to trimers. The geometry, first hyperpolarizability and harmonic vibrational wavenumbers were calculated by means of density functional theory (DFT) with the B3LYP/6-31G(d) level of theory. Good consistency was found between the calculated and the experimental structure, IR, and Raman results. The first hyperpolarizability β_tot of the title compound is about 1.75 times more than that of the reference crystal KDP. The complex impedance has been investigated in relation to the temperature and frequency ranges 297 and 373 K and 1 to 100 KHz, respectively. The conductivity temperature variation shows a typical Arrhenius-type behavior with a linear dependence on logarithm of conductivity. Transport properties in this material appear to be due to proton hopping mechanism.     

Octa­hedral–tetra­hedral framework structures of InAsO4·H2O and PbIn(AsO4)(AsO3OH)

Indium arsenate(V) monohydrate, InAsO₄·H₂O, (I), crystallizes in the structure type of MnMoO₄·H₂O. The structure is built of In₂O₈(H₂O)₂ dimers (mean In—O = 2.150 Å) corner‐linked to slightly distorted AsO₄ tetra­hedra (mean As—O = 1.686 Å). The linkage results in a three‐dimensional framework, with small voids into which the apical water ligand of the InO₅(H₂O) octa­hedron points. The hydrogen bonds in (I) are of medium strength. Lead(II) indium arsenate(V) hydrogen arsenate(V), PbIn(AsO₄)(AsO₃OH), (II), represents the first reported lead indium arsenate. It is characterized by a framework structure of InO₆ octa­hedra corner‐linked to AsO₄ and AsO₃OH tetra­hedra. The resulting voids are occupied by Pb₂O₁₀(OH)₂ dimers built of two edge‐sharing highly distorted PbO₆(OH) polyhedra (mean Pb—O = 2.623 Å). The compound is isotypic with PbFe^III(AsO₄)(AsO₃OH). The average In—O bond length in (II) is 2.157 Å. In both arsenates, all atoms are in general positions.     

Electroactivity of Cacodylic Acid in Aqueous and Nonaqueous Media

Abstract

The electroreduction of dimethylarsenic acid (cacodylic acid), (CH₃)AsO₂H, and methylarsonic acid, (CH₃)ASO₃H₂, in both nonaqueous and aqueous buffer electrolytes, is described.     

Raman- und infrorofspektroskopische Untersuchungen on Alkylderivaten der Arsensäure. V1 Die Schwingungsspektren der Dimethyl- und Diäthylarsinsäure sowie deren Reaktionsprodukte mit Chlorwasserstoff

RAMAN and IR Spectroscopic Investigation on Alkyl Derivatives of Arsenic-Acid. V. Vibrational Spectra of Dimethyl and Diethyl Arsinic Acid and their Reaction Products with HCl The RAMAN and IR spectra of (CH₃)₂AsO₂H–partially deuterated–and (C₂H₅)₂AsO₂H and of the reaction products of these acids with HCl (solid and in concentrated aqueous solution) are discussed. The symmetry of the R₂AsO₂H skeleton is C_s. of the [R₂As(OH)₂]+ ion very probably C_2v. Whereas (CH₃)₂AsO₂H gives with HCl only a compound (CH₃)₂ACO₂H · HCl (connected by H bonds), the weaker (C₂H₅)₂AsO₂H is able to form a salt [(C₂H₅)₂As(OH)₂]Cl. The H bonds in the substances are discussed.     

M3+(H2AsO4)(H2As2O7) (M3+ = Al,Ga) and In2(H2AsO4)2(H2As2O7)2: a new layer structure type and a new framework structure type containing the rare H2As2O72− group

The crystal structures of hydrothermally synthesized aluminium dihydrogen arsenate(V) dihydrogen diarsenate(V), Al(H₂AsO₄)(H₂As₂O₇), gallium dihydrogen arsenate(V) dihydrogen diarsenate(V), Ga(H₂AsO₄)(H₂As₂O₇), and diindium bis[dihydrogen arsenate(V)] bis[dihydrogen diarsenate(V)], In₂(H₂AsO₄)₂(H₂As₂O₇)₂, were determined from single‐crystal X‐ray diffraction data collected at room temperature. The first two compounds are representatives of a novel sheet structure type, whereas the third compound crystallizes in a novel framework structure. In all three structures, the basic building units are M ³⁺O₆ octahedra (M = Al, Ga, In) that are connected via one H₂AsO₄⁻ and two H₂As₂O₇²⁻ groups into chains, and further via H₂As₂O₇²⁻ groups into layers. In Al/Ga(H₂AsO₄)(H₂As₂O₇), these layers are interconnected by weak‐to‐medium–strong hydrogen bonds. In In₂(H₂AsO₄)₂(H₂As₂O₇)₂, the H₂As₂O₇²⁻ groups link the chains in three dimensions, thus creating a framework topology, which is reinforced by weak‐to‐medium–strong hydrogen bonds. The three title arsenates represent the first compounds containing both H₂AsO₄⁻ and H₂As₂O₇²⁻ groups.     

Structure and Properties of UO2(H2AsO4)2 · H2O

UO₂(H₂AsO₄)₂ · H₂O was synthesized by dissolving elemental uranium in arsenic acid (80.5%) for twelve weeks at room temperature. The resulting small crystals were transparent and of yellow‐green color. The crystal structure was refined from single‐crystal X‐ray data: C2/c, a = 1316.4(3) pm, b = 886.2(2) pm, c = 905.0(3) pm, β = 124.41(3)°, R1 = 0.023, wR2 = 0.060, 981 structure factors, and 65 variable parameters. The uranium atoms of this new structure type are coordinated by two very close oxygen atoms in linear arrangement. Four further oxygen atoms which belong to four different AsO₄ tetrahedra and the oxygen atom of the water molecule complete the 7‐fold coordination of the uranium atoms. [UO₂(H₂O)]²⁺ and two H₂AsO₄^– units form infinite electroneutral chains which are the main building units of the structure and which are interconnected by hydrogen bridging bonds. IR heating experiments show that dehydration around 500 K leads to a complete decomposition of the structure. Magnetic measurement gave a diamagnetic behavior with a susceptibility of χ = –8.68 10^–9 m³/mol in good agreement with the diamagnetic increment of the compound (χ = –8.20 10^–9 m³/mol) calculations with U⁶⁺.     

Computational chemistry and molecular simulations of phosphoric acid

Quantum mechanics (QM) calculations, molecular dynamics (MD) simulations using the condensed‐phase optimized molecular potentials for atomistic simulation studies (COMPASS) force field, and the atom‐centered density matrix propagation (ADMP) approach have been used to investigate properties of phosphoric acid (PA). QM using B3LYP/6‐31++G(d,p) density functional theory were used to calculate gas‐phase proton affinities and interaction energies of PA and its derivatives. Detailed single coordinate driving, followed by quadratic synchronous transit optimization was used to determine energy barriers for different proton transfer (PT) pathways. Determined energy barrier heights in ascending order are (unit: kJ/mol): H₃O⁺→H₃PO₄ (0); H₄P₂O₇→H₃PO₄ (2.61); H₃PO₄→H₂PO (5.31); H₄PO→H₃PO₄ (～7.33); H₃PO₄→H₄P₂O₇/H₃PO₄→H₃PO₄ (15.99); H₄P₂O₇→H₂O (28.61); H₃PO₄→H₂O (47.14). The COMPASS force field was used to study condensed‐phase properties of PA. Good agreement between experimental data and MD results including density, radial distribution functions, and self‐diffusion coefficient at different temperatures provides validation of the COMPASS force field for PA. Finally, preliminary ADMP studies on a cluster of three PA molecules shows that the ADMP approach can reasonably describe the PT and self‐dissociation processes in PA. © 2010 Wiley Periodicals, Inc. Int J Quantum Chem, 2011     

Influence of pressure in the 0.1–100 MPa interval on the first dissociation constant of arsenous acid in water solutions at 298.15 K

The influence of pressure on the dissociation of arsenous acid H₃AsO₃ was studied at 298.15 K by the potentiometric method. In the pressure interval from 0.1 to 100 MPa the values of logK ₁^o = −9.32 + 0.00246P. The change in the molar volume of the reaction of the dissociation of H₃AsO₃ from the first step (ΔV ₁^o = −15.4 ± 1 cm³/mol) and the partial molar volume of its dissociation product, H₂AsO₃⁻ (V ^o = 32.1 ± 1 cm³/mol) were determined.     

Polarised vibrational spectra of Bet·H3AsO4 single crystal: Part II. Low temperature studies

Polarised infrared transmission (4000–400 cm⁻¹) and Raman (3500–10 cm⁻¹) spectra of betaine ortho-arsenic acid crystal ((CH₃)₃NCH₂COO·H₃AsO₄; abbreviated as BA) were measured at various temperatures and analysed. The temperature evolution of the hydrogen bonds stretching vibrations (νOH) apparent in the polarised infrared transmission spectrum (||c axis) shows that the O(4)⋯O(4) hydrogen bonds being almost parallel to the spontaneous polarisation direction plays an important role in the ferroelectric phase transition. New experimental proofs for the deformation of the AsO₄ group in H₃AsO₄ acid and rotation of betaine molecules related to the ordering of the hydrogen bonds at the ferroelectric phase transition were found.     

Preparation and structural study of a novel nonlinear molecular material: the -histidinum dihydrogenarsenate orthoarsenic acid crystal

-Histidinium dihydrogenarsenate orthoarsenic acid (LHA) crystal ;

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belongs to P2₁ space group of the monoclinic system, Z=2, a=9.264(2) Å, b=8.929(2) Å, c=8.874(2) Å, β=108.61(3)°. The crystal is isomorphous to

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(LHP) crystal. The H₂AsO₄⁻ anions and H₃AsO₄ molecules are joined into layers parallel to the (100) crystallographic planes by the O–HO type hydrogen bonds. The histidinium cations occupy the space between the layers. The histidinium cation posses the carboxylic COO⁻ group. The positive charges appear in the ring (the proton is attached to the =N(3)– nitrogen) and in the ammonium group. The differential scanning calorimetric (DSC) diagram does not show any phase transition till 100 K. The infrared spectrum fully confirms the X-ray crystal structure. The LHA crystal is a good second harmonic generator (0.46 relative to KDP)