Yttrium Coordination Compounds with Nitrilotris(Methylenephosphonic Acid)

Russian Journal of Coordination Chemistry - Nitrilotris(methylenephosphonato)yttrium [YH3{N(CH2PO3)3}] · 2H2O (I) and octapotassium monohydro-bis-nitrilotris(methylenephosphonato)yttriate...     

Degradation of Amino-(3-methoxyphenyl)methanephosphonic Acid by Alternaria sp

Alternaria sp. isolated from the surface of carrot ( Daucus carota ) seeds appeared to be able to degrade amino-(4-methoxyphenyl)-methanephosphonic acid using it as a sole source of carbon, nitrogen, and phosphorus for growth.     

Crystal Structure of Tetra- and Pentasodium Salts of Nitrilotris(methylenephosphonic Acid)

Tetra- and pentasodium salts of nitrilotris(methylenephosphonic acid) N(CH₂PO₃)₃H₆ (NTP) have been studied by single-crystal X-ray diffraction and spectroscopy. [Na₈(H₂O)₁₂{NH(CH₂PO₃)₃H}₂] · H₂O crystallizes in triclinic system, space group P1?, Z = 1, a = 7.1515(2) Å, b = 11.1590(3) Å, c = 12.0583(3) Å; α = 92.077(2)°, β = 106.145(2)°, γ = 5.628(2)°, CCDC No. 1432091. The crystal structure comprises two-dimensional layers lying along planes (011?), where dimeric molecules are linked by bridges each comprising four Na hydration octahedra. The [Na₅(H₂O)₁₁{NH(CH₂PO₃)₃}] · 2H₂O crystals are monoclinic, space group P2₁/n, Z = 4, a = 6.3024(2) Å, b = 21.5639(7) Å, c = 18.1608(6) Å; β = 91.261(3)°, CCDC No. 1497161. The crystal packing comprises alternating layers in planes [020] made of two-dimensional nets of Na hydration polyhedra, and columns of Na hydration octahedra lying in planes [040], with acid moieties in between.     

Precipitation of Copper(II) with 1,2-Dibenzoylhydrazine from Aqueous Ammonia Solution

The physicochemical characteristics of 1,2-dibenzoylhydrazine relevant to precipitation of copper(II) with this reagent were studied.     

Photoinduced Structural Volume Changes in Aqueous Solutions of Blepharismin

Abstract— Employing time-resolved photoacoustics we measured the structural volume changes (ΔV_ri) occurring after photo-excitation of blepharismin (BPR) aqueous solutions; an expansion occurring in the subnanosecond timescale is followed by a back contraction within some hundreds of nanoseconds. The magnitude of the ΔV_ri strongly depends on pH, allowing the determination of the pK_a of BPR with this method. The values so measured are very close to those found by means of UV-visible absorption spectroscopy. The presence of water-soluble electron acceptors or donors (hexacyanoferrate [III] hexacyanofer-rate [II]) as well as the concentration of oxygen do not affect the magnitude or the kinetics of the structural volume changes. On the contrary, we detect a strong deuterium effect; this suggests that the observed ΔV_ri are related to an altered hydrogen bond pattern of the excited state of the pigment with respect to the ground state. Comparative measurements with the parent compound hypericin are also reported, suggesting that the photo-induced expansion-contraction pattern is a general characteristic of polyhydroxylated quinones.     

Vanadium(III) Complexes with Picolinic Acid and Dipicolinic Acid in Aqueous Solution

The complex species formed in aqueous solution (25 ^∘C, I = 3.0 mol-dm⁻³ KCl ionic medium) between V³⁺ cation and the ligands: picolinic acid (Hpic, HL) and dipicolinic acid (H₂dipic, H₂L), have been studied potentiometrically and by spectrophotometric measurements. The application of the least-squares computer program LETAGROP to the experimental emf (H) data, taking into account the hydrolytic species of V³⁺ ion, indicates that under the employed experimental conditions, the formation of the complexes [VL]²⁺, [V(OH)L]⁺, [VL₂]⁺, [VL₃], [V₂OL₄] with picolinic acid and the complexes [VL]⁺, [V(OH)L], [V(OH)₂L]⁻, [V(HL)(L)], and [VL₂]⁻ with dipicolinic acid were observed. The stability constants of the complexes formed were determined by potentiometric measurements, and spectrophotometric measurements were done in order to perform a qualitative characterization of the complexes formed in aqueous solution.     

Thermochemical Study of Mixed-Ligand Manganese(II) Ethylenediaminetetraacetate Complex with Ammonia in Aqueous Solution

Formation of the mixed-ligand complex [MnEdtaNH₃]^2– and of the Mn(II) ammine complex is studied by calorimetry at 298.15 K and ionic strength I = 0.5 (NH₄NO₃). Thermodynamic parameters of the reaction of attachment of the additional ligand to the manganese(II) chelate are determined; its probable mechanism is discussed.     

Interactions of Copper(I) Phenanthroline Chelate with Polyadenylic-Polyuridylic Acid in Aqueous Dioxane

Acid-base transformations in the system copper(I) phenanthroline chelate [Cu(phen)₂]⁺aq-poly-adenylic-polyuridylic acid in aqueous dioxane were studied by spectrophotometry. Changes in band intensi-ties, positions were revealed in the visible, near UV regions, dependent on the pH of the solution.Factor analysis was used to show that the absorption variance on titration of copper(I) bisphenanthrolinechelate is determined by mutual transformations of three spectral forms of complexes. Concentration profiles were calculated for compounds prevailing in the solution. In the presence of polyadenylic-polyuridylic acid, an additional spectral form appears as a result of a short-wave shift of the d-* MLCT transition in the copper(I) chelate complex. Analysis of the calculated concentration profiles established that the new complex is formed at pH 5.2-5.6 from the bisphenanthroline chelate and the double-helix rod-like form of the polymer.     

Different Directions of the Reaction of 1-(2-Oxocycloalkyl)-ethane-1,1,2,2-tetracarbonitriles with Aqueous Ammonia

Russian Journal of Organic Chemistry - Tetracyanoethylene adducts of cycloalkanones, 1-(2-oxocycloalkyl)ethane-1,1,2,2-tetracarbonitriles, reacted with aqueous ammonia at room temperature to give,...     

Kinetic Stability of Indium(III) Complexes with Azaporphyrins in Aqueous Sulfuric Acid

Stability of chloro(octaphenyltetraazaporphinato)indium(III) and chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in 90-98 % aqueous sulfuric acid was studied. Kinetic parameters of solvoprotolytic dissociation of the complexes were determined, and a mechanism of the reaction was proposed. Diaza substitution results in more stable complexes than tetraaza substitution. The state of chloro(2,8,12,18-tetrabutyl-3,7,13,17-tetramethyl-5,15-diazaporphinato)indium(III) in a proton-donor medium was studied to show that the acid-base interaction involves one by one two meso-nitrogen atoms. Dissociation constants of the resulting acid forms were determined.     

Protonation of nitrilotris(methanephosphonic) acid and its salts in aqueous solutions

The reactions of aqueous solutions of nitrilotris(methanephosphonic) acid and its salts, and also of 1-hydroxyethane-1,1-diphosphonic acid and tetraethylammonium salt of 1-aminoethanephosphonic acids with hydrochloric acid at 25°C were studied by the dilatometric method. The results were discussed in the context of the idea on the existence of the betaine form of an acid molecule and its anions and the existence of proton chelates of aminophosphonic compounds in solutions.     

Solution Characteristics for Adsorption of Copper Ion with Iron(III) Hydroxide from Aqueous Ammonia Solution

The distribution of copper ion species in aqueous ammonia solution is evaluated as a function of pH by a numerical approach. Adsorption of copper on colloidal iron(III) hydroxide in solutions of total ammonia (0.14-1.2 M) are performed at various values of pH. The maximum efficiency of adsorption occurs when the sum of the fractions of the species Cu(NH₃)²⁺, Cu(NH₃)₂²⁺ and Cu(NH₃)₃²⁺ in the solution reaches its maximum. With varied solution pH, the distribution of copper species is the determining factor for maximum adsorption, whereas the surface properties of the adsorbing particles show smaller effects under the test conditions.     

Mechanistic Study of Oxidation of Palladium(II) by Cerium(IV) in Aqueous Acid

The kinetics of oxidation of Pd^II by Ce^IV have been studied spectrophotometrically in HClO₄ media at 40 °C. The reaction is first order each in [Ce^IV] and [Pd^II] at constant [H⁺]. Increasing [H⁺] accelerates the reaction rate with fractional order in [H⁺]. The initially added products, palladium(IV) and cerium(III) do not have any significant effect on the reaction rate. At constant acidity, increasing the added chloride concentration enhances the rate of reaction. H₃Ce(SO₄)₄⁻ and PdCl₄²⁻ are the active species of oxidant and reductant respectively. The possible mechanisms are proposed and the reaction constants involved have been determined.     

Photopolymerization of Acrylonitrile by Potassium TrisoxalatocobaItate(III) in Aqueous Perchloric Acid

Results of a kinetic study on photopolymerization of acrylonitrile by potassium trisoxalatocobaltate(II1) in aqueous perchloric acid medium (pH = 1) by use of light of 365 nm wavelength at 30 |Mg 0.1°C are presented. All reactions were carried out under completely deaerated conditions. Certain important features of the photopolymerization are described. The rate of polymerization R_p was followed by gravimetric estimation of polymer formed and rate of disappearance of complex - R_c by spectrocolorometric estimation of complex disappearing. R_p was found to be directly proportional to [M]^3/2, k_ε ^1/2, and I^1/2, where P[M], k_ε, and I refer to concentration of acrylonitrile, light absorption fraction of the complex, and light intensity, respectively. -R_c was found to be directly proportional to k_ε and I. A reaction scheme is drawn and kinetic expressions derived on the basis of that scheme are given.     

Extraction of Mercaptans from Light Hydrocarbon Mixtures with Aqueous Ammonia

Results of laboratory studies of the extraction of light mercaptans (methyl, ethyl, and propyl mercaptans) from hydrocarbons mixtures with a 25% aqueous solution of ammonia (caustic ammonia) are presented and discussed. It is shown that aqueous ammonia can in principle be used for controlled demercaptanization of light hydrocarbon fractions and liquefied hydrocarbon gases containing hydrogen sulfide and lower mercaptans. The advantage of this demercaptanization method over the conventional processes of alkali treatment is that there is no stage of oxidative catalytic regeneration of a spent alkali and there are no its highly toxic wastes, sulfurousalkaline waste waters. The regeneration of a spent (saturated with sulfurous compounds) aqueous ammonia can be comparatively easily performed by its heating (boiling), which leads to a hydrolytic decomposition of ammonium sulfides and mercaptides to release their constituent gases: hydrogen sulfide, mercaptans, and ammonia. Ammonia is recycled into the process as freshly prepared (regenerated) caustic ammonia.

     

Kinetics of Dissociation of Iron(III) Complexes of Tiron in Aqueous Acid

The kinetics of dissociation of the mono, bis, and tris complexes of Tiron (1,2-dihydroxy-3,5-benzenedisulfonate) have been studied in acidic aqueous solutions in 1.0 M HClO(4)/NaClO(4), as a function of [H(+)] and temperature. In general, the kinetics can be explained by two reactions, (H(2)O)Fe(L)(n)(-1) + H(2)L right arrow over left arrow (H(2)O)Fe(L(n)H) + H(+) (k(n), k(-n)) and (HO)Fe(L)(n)(-1) + H(2)L right arrow over left arrow (H(2)O)Fe(L(n)H) (k(n)', k(-n)'), a rapid equilibrium, (H(2)O)Fe(L(n)H) right arrow over left arrow (H(2)O)Fe(L)(n) + H(+) (K(cn)), and the formation constant (H(2)O)Fe(L)(n)(-1) + H(2)L right arrow over left arrow (H(2)O)Fe(L)(n) + 2H(+). For n = 1, the reaction was observed at 670 nm, and at [H(+)] of 0.05-0.5 M at temperatures of 2.0, 14.0, 25.0, and 36.7 degrees C. For n = 2, the analogous conditions are 562 nm, at [H(+)] of 1.5 x 10(-3) to 1.4 x 10(-2) M at temperatures of 2.0, 9.0, and 14.0 degrees C. For n = 3, the conditions are 482 nm, at pH 4.5-5.7 in 0.02 M acetate buffer at temperatures of 1.8, 8.0, and 14.5 degrees C. The rate or equilibrium constants (25 degrees C) with DeltaH or DeltaH degrees (kcal mol(-1)) and DeltaS or DeltaS degrees (cal mol(-1) K(-1)) in brackets are as follows: for n = 1, k(1) = 2.3 M(-1) s(-1) (8.9, -27.1), k(-1) = 1.18 M(-1) s(-1) (4.04, -44.8), K(c1) = 0.96 M (-9.99, -33.6), K(f1) = 2.01 M (-5.14, -15.85); for n = 2, k(-2)/K(c2) = 1.9 x 10(7) (19.9, 41.5) and k(-2)'/K(c2) = 1.85 x 10(3) (1.4, -38.8) and a lower limit of K(c2) > 0.015 M; for n = 3, k(3) = 7.7 x 10(3) (15.8, 12.3), k(-3) = 1.7 x 10(7) (16.2, 28.9), K(c3) = 7.4 x 10(-5) M (4.1, -5.1), and K(f3) = 3.35 x 10(-8) (3.7, -21.7). From the variations in rate constants and activation parameters, it is suggested that the Fe(L)(2) and Fe(L)(3) complexes undergo substitution by dissociative activation, promoted by the catecholate ligands.     

Dioxomolybdenum(VI) Complex with (1-Oxyethylidene)diphosphonic Acid in an Aqueous Medium: Synthesis and Crystal Structure

Russian Journal of Coordination Chemistry - A new complex of hexaammonium bis(1-oxyethylidenediphosphonate)dioxomolybdenum tetrahydrate (NH4)6[MoO2(L)2] · 4H2O (I) (H4L is...