Nitrate complexes of divalent palladium and platinum

Conclusions Some nitrate complexes of Pd(II) and Pt(II) were synthesized. The absorption bands of the nitrate groups in the IR spectra of the obtained complexes were studied in the 900–1700 cm^–1 region. A study was also made of the NMR spectra of the nitrate complexes of Pt(II) in D₂O.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 7, pp. 1677–1679, July, 1977.     

Interaction of Pd(II) with Glutamic Acid

Pd(II) complexes with glutamic acid of the composition K[Pd(HGlu)Cl₂] (I) and [Pd(HGlu)₂] (II) were synthesized and studied by IR and electronic absorption spectroscopy methods. Pd²⁺–H₂O–Cl^– and Pd²⁺–H₂O–Cl^––H₂Glu systems were analyzed by pH-metric titration. The most essential Pd(II) complex forms were established by mathematical modeling and their formation constants were calculated. The electronic absorption spectra of complexes I and II were measured in aqueous and physiological solutions. Complex I was found to be biologically active and to exhibit antimetastatic properties.     

Heterocomplexes in liquid mixtures MeOH—HF

The IR spectra and densities of MeOH—HF liquid mixtures were measured for component molar ratios ranging from 12 : 1 to 1 : 3. The IR spectra of all of the solutions exhibit bands with maxima at 3500, 2600, and 1800 cm^–1 and continuous absorption (CA) in the region of 3500—1300 cm^–1. The intensities of these bands and the CA increase with an increase in the HF concentration. A similar behavior was found for the difference between the experimental solution density and the additive sum of the solution component densities. Ab initio SCF calculations of the (MeOH)_5–n (HF) _n cyclic complexes (n = 0—5) were performed using the 6-31G basis set. The observed properties of MeOH—HF liquid mixtures may be due to the formation of heterocomplexes with a stable cyclic fragment consisting of more than four MeOH and HF molecules.     

Mercury(II) halide adducts of a dicarboxylate-like ligand: Crystal structures of polymeric mercury(II) complexes with 1,4-diazoniobicyclo[2.2.2]octane-1,4-diacetate

Three mercury(II) complexes containing double-betaine and halide ligands, [(HgCl₂)₂(L¹)] _n (1), [(HgBr₂)₂(L¹)(H₂O)₂] _n (2), and [2HgCl₂(HL¹)·Hg₂Cl₆] _n (3) [L¹=^–O₂CCH₂N⁺(CH₂CH₂)₃-N⁺H₂CO₂ ^–], have been prepared and shown to have polymeric structures by single-crystal X-ray analysis. Complex (1) exhibits an infinite zigzag chain in which each mercury(II) atom is coordinated by pairs of carboxylate oxygen atoms and chloride ligands in a distorted tetrahedral geometry. In complex (2), the mercury(II) atom is in an unusual square-planar coordination geometry, and weak mercury-ligand and hydrogen bonding extend the structural skeletons into a three-dimensional network. Complex (3) consists primarily of an assembly of HgCl₂(HL¹) moieties and [Hg₂Cl₆]^– anions, and the mercury(II) atoms are in planar T-shaped and distorted tetrahedral coordination environments, respectively. The resulting three-dimensional network is based on the cross-linkage of nearly planar, wide ribbons running in thea direction.     

Flash photolysis of chloride complexes of Cu(II) in organic solvents

By means of flash photolysis and low-temperature spectrophotometry, the formation of a complex between a Cu(I) ion and a peroxy radical of the solvent has been detected in ethanol, isopropanol, and dimethylformamide. The peroxy radical is generated in a reaction of a solvent radical with a molecule of dissolved oxygen. The solvent radical appears as a result of photoreduction of chloride complexes of Cu(II). The radical complex has a band in the optical absorption spectrum with a maximum at 415–420 nm in ethanol and isopropanol. The rate of formation of this complex is determined mainly by the reaction of the radical of the matrix (R^.) with complexes of bivalent copper. The rate constant of this process in isopropanol at room temperature is (2–3)·10⁸ liters/ mole·sec. Disappearance of the radical complex Cu(I)...RO₂ ^. takes place in a reaction with complexes Cu²⁺ _solv and CuCl⁺ with a rate constant of 2.3·10⁷ liters/mole·sec at room temperature.Translated from Teoreticheskaya in iÉksperimental'naya Khimiya, Vol. 22, No. 1, pp. 39–44, January–February, 1986.     

Infrared spectra of hexathiocyanate complexes of nickel

Conclusions The IR absorption spectra of hexathiocyanate complexes of nickel (II) were studied in the crystalline state (400–4000 cm^–1) and in aqueous solutions (2000–2400 cm^–1). All the investigated compounds contained monodentate isothiocyanate groups.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 11, pp. 2460–2464, November, 1971.     

Indirect atomic absorption and atomic emission spectrometric determination of antazoline,hydralazine and amiloride hydrochlorides and quinine sulphate

Ion-association complexes of antazoline HCl [I], hydralazine HCl [II], amiloride HCl [III] and quinine sulphate [IV] with [Co(SCN)₄]^2– and [Co(NO₂)₆]^3– were precipitated and the excess unreacted cobalt complex was determined. A new method using atomic emission and atomic absorption spectrometry for the determination of the above drugs in pure solutions and pharmaceutical preparations is given. The drugs can be determined in the ranges 0.3–3.0, 0.19–1.96, 0.3–3.0, and 0.78–7.82 mg/25 ml solutions of I, II, III, and IV, respectively, with mean relative standard deviations of 0.65–2.03 % and recovery values of 95.76–101.2% indicating high precision and accuracy.     

Solvent effects on the ultraviolet absorption spectrum of mercury atom

Absorption spectrum of mercury dissolved in hexane and heptane in the region 280–180 nm was found to consist of three bands. These bands were assigned to the ¹S₀ → ¹P₁ transition (A band, λ = 254 nm), to the ¹S₀ → ³P₂ transition (B band, λ = 226 nm) and to the ¹S₀ → ¹P₁ transition (C band, λ = 190 nm) of a mercury atom placed into a liquid cell. The B and C absorption bands of mercury in liquid solutions were observed for the first time. It was found that the A band and the C band have, respectively, distinct doublet and triplet structure, while the doublet structure of the B band is only slightly seen. The oscillator strengths of all three bands of mercury in solutions were estimated. The structure of the C, A and B bands of mercury in solutions most probably results from the removal of the degeneracy of the excited states ¹P₁, ³P₁ and ³P₂ of a mercury atom, placed into a cell of low symmetry.     

Angular Overlap Studies of Mono-(Aminodiphosphonato)Copper(II) Complexes in Aqueous Solutions

Electronic absorption spectra of copper(II) complexes with iminodimethylenephosphonates R-N(CH₂PO₃H₂)₂ type (L, R-dmp), in aqueous solution have been characterized and quantitatively interpreted. The geometry of species in aqueous solution at pH 7–8 has been assumed on the basis of our previous combination of UV spectrophotometric measurements and ESR spectra, as well as data obtained from potentiometric titration. The ligand-field spectra (d–d transitions) of the [CuL(H₂O)_x]^2– chromophores (where x = 2, 3) have been treated by the angular overlap model (AOM) and C _2v symmetry. Low-symmetry splittings of the broad asymmetric bands in the spectra of solutions at room temperature were resolved by Gaussian analysis. The effect of the and bonding of the tridentate (and tetradentate) ligands (with oxygen-donor and nitrogen-donor ligators) on the central metal ion has been described in the ligand-field framework.     

Zinc(II), cadmium(II) and mercury(II) halide pyrrolidine-2-selone complexes

Summary Reaction of zinc(II), cadmium(II) and mercury(II) halides with Pyrrolidine-2-selone yields complexes of general formula ML₂X₂ (X = Cl, Br or I) which are monomeric, tetrahedral and Se-bonded to the metals. The comparison of their i.r. spectra with the spectrum of the free ligand confirms that the band at 1005 cm^–1 in Pyrrolidine-2-selone arises predominantly from the C=Se stretching vibration. The metalhalogen absorptions above 200 cm^–1 are identified.This work was supported by the National Research Council (C.N.R.) of Italy.     

IR spectra of hydrogen fluoride solutions in n-propanol

The densities of solutions of HF in n-PrOH were measured at different mole ratios of the components (from 1 : 12 to 3 : 1), and their IR spectra were recorded. The spectra of all the solutions exhibit absorption bands at 3500, 2600, and 1800 cm^–1 and continuous absorption (CA) in the frequency range from 3500 to 1300 cm^–1. The intensities of these bands and CA increase in proportion to the concentration of HF in solution. The difference between the experimental solution density and the calculated additive sum of the densities of the solution components behaves analogously. The formation of heterocomplexes with a stoichiometric ratio greater than 3 : 1 in the HF solutions in propanol was revealed. These heterocomplexes have large identical structural fragments with the strong quasi-symmetric H-bond. The results of calculations of the stretching vibration frequencies and relative stability of different cyclic pentamers suggest that such a fragment is the most stable cyclic heteropentamer, (HF)₂(nPrOH)₃, in which the HF molecules occupy the neighboring positions.     

Organosilicon Amidophosphates and Their Eu and Er Complexes in Solutions and Films: Spectral and Luminescence Properties

Fluorescence and fluorescence excitation spectra of phosphorus-containing organosilicon ligands O = PX₂NHR (X = NMe₂, OPh; R = CH₂CH₂CH₂Si(Oet)₃ and their Eu(III) complexes in acetonitrile solutions and in films are studied. In UV region (285–420 nm), bis(dimethylamido)triethoxysilylpropylamidophosphate (X = NMe₂) and diphenyltriethoxysilylpropylamidophosphate (X = OPh) exhibit two emission bands, whose position and intensity depend on the nature of substituents at the phosphorus atom. The Eu complexes show the ligand and the cation luminescence. The emission bands of coordinated ligands are shifted to long-wave region. The cation luminescence appears as three or four bands due to f-f transitions from the excited ⁵ D ₀ level to the lower ⁷ F _1–4 levels. The most intense transition is ⁵ D ₀ → ⁷ F ₂. The emission band in a region of 420 nm appears in solutions and films prepared from both pure ligands and their Eu(III) complexes. This band is due to luminescence of spatially crosslinked nanoparticles of sesquioxane structure. The intensity ratio of the Eu³⁺ emission bands changes when going from solutions to films, the emission intensity increases in a range of 420 nm. Films containing incorporated Er complexes with amidophosphates show intense luminescence of a matrix at 430 nm and a series of weak narrow bands due to the Er³⁺ cation at 550–700 nm.__________Translated from Koordinatsionnaya Khimiya, Vol. 31, No. 7, 2005, pp. 550–558.Original Russian Text Copyright © 2005 by Semenov, Cherepennikova, Klapshina, B. Bushuk, S. Bushuk, Douglas.     

Kinetics and Mechanism of Electroreduction of Ammonia and Hydroxyammonia Complexes of Zinc(II) on a Dropping Mercury Electrode

It is found that the equilibrium potential of the Zn(Hg)/Zn(II) system depends on the concentration of ammonia molecules and solution pH. The dependence conforms to the literature data on the stability constants for ammonia and hydroxyammonia complexes of zinc. Their reduction on a dropping mercury electrode in solutions of pH 9.2–12 and [NH₃] = 0.05–2 M yields one irreversible cathodic wave with a diffusion limiting current. In dilute supporting electrolytes, the plateau of the latter is preceded by a maximum due to accumulation of insoluble reduction products on the surface of the mercury drop. The pH and [NH₃] dependences of the half-wave potential of waves that are undistorted by a maximum are analyzed with allowance made for a change in the composition of zinc(II) complexes in the bulk solution. According to the analysis, the slow two-electron electrochemical stage involves complexes Zn(NH₃)₂ ²⁺ that form from complexes present in solution in preceding reversible chemical reactions. The effect the supporting-electrolyte concentration has on the electroreduction rate of zinc(II) complexes and the mechanism of the electrochemical stage is discussed.     

Bis-(tetraethylammonium)[tetraazidocuprate(II)] and catena-di-μ-1,1-azido-[di-μ-1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)]

Two new copper(II) azido complexes, namely bis-(tetraethylammonium)[tetraazidocuprate(II)] (1) and catena-di--1,1-azido-[di--1,1-azido-bis-(2,4-dimethylpyridine)dicopper(II)] (2), have been prepared and characterized by spectroscopic and crystallographic methods. Complex (1) consists of isolated NEt⁺ ₄ cations and [Cu(N₃)₄]^2– anions. The site symmetry around the copper atom in the anion is 4/m. Complex (2) features a 1 D chain structure, five coordinated square pyramidal copper(II) atoms with both azides functioning as -1,1-bridges. The i.r. spectra reveal that both complexes contain asymmetric azido ligands. The solid and solution electronic spectra of (1) and (2) show very strong absorption bands in the visible region associated with N^– ₃ Cu^II charge-transfer transitions. The e.p.r. spectra of powder samples and solutions at room temperature were recorded and discussed.     

Syntheses of new oxovanadium(IV) complexes with some new Schiff bases derived from salicylaldehyde or substituted salicylaldehyde and 3-aminothiophenol

Summary The syntheses of several new oxovanadium(IV) complexes of new Schiff bases derived from Salicylaldehyde, 5-ch orosalicylaldehyde, 5-bromosalicylaldehyde, 5-nitrosalicylaldehyde, 4-methoxysalicylaldehyde, 2-hydroxy-l-naphthaldehyde and 3-aminothiophenol are described. The complexes, which are of the VOL₂ type, have been characterized on the basis of elemental analysis, i.r. and electronic absorption spectra, and magnetic susceptibility measurements. The Schiff bases behave as bidentate ligands and a five-coordinate square-pyramidal structure is suggested for the complexes which exhibit two or three spin-allowed d-d bands atca. 12000, 17000 and 22000 cm^–1. The v(V=0) vibration occurs in the 940–980 cm^–1. range. The complexes exhibit normal magnetic moments (µ_eff = 1.71-1.73 B.M.) at room temperature.     

Ir spectra of the simplest stable proton solvates in methanol and ethanol

The spectra of (MeOH)₂H⁺ and (EtOH)₂H⁺ proton disolvates formed by strong symmetrical hydrogen bonding were separated from the multiple frustrated total internal reflection (MFTIR) IR spectra of solutions of HCl in methanol and ethanol. These spectra show a large number of rather narrow bands, exceeding the number of bands in the spectra of the pure alcohols and are in accord with a model, in which the generation of continuous absorption in solutions of strong acids is a consequence of the interaction of vibrations for protons in a strong, symmetrical hydrogen bond with the vibrations of other groups of proton disolvates.Translated from Izvestiya Akademii Nauk SSSR, Seriya Khimicheskaya, No. 1, pp. 217–220, January, 1991.     

IR spectroscopic study of adsorption of ammmonia on Brønsted acid centers of a fluorinated surface of silica

The adsorption of aqueous ammonia solution vapor on a fluorinated surface of aerosil was studied by IR spectroscopy. The adsorption of NH₃ is accompanied by the appearance of absorption bands at 740, 1450, and 3330 cm^–1 in the IR spectra. The surface compounds were identified from the results of a study on the thermal degradation of adsorbed complexes and an analysis of literature data. The IR absorption bands at 1450 and 3330 cm^–1 correspond to deformational and stretching vibrations of the N-H bonds of the ammonium cation, The 740 cm^–1 band was assigned to the vibrations of the Si-F bonds in the complex anion, containing a fragment of SiO₂ surface, a fluorine atom, a hydroxyl group and a molecule of water. In this surface-coordinated compound, the silicon atom has a coordination number of six.Translated from Teoreticheskaya i Éksperimental'naya Khimiya, Vol. 22, No. 6, pp. 747–751, November–December, 1986.     

Gold bromide complexes in acidic aqueous solutions from 25° to 300°C. A laser raman spectroscopic study

Raman spectra of gold bromide complexes in acidic solutions (pH=–0.3–3) have been recorded at 25° to 300°C and at pressures on the liquid vapor curve for the system. At 25°C, only the square planar Au(III) bromide complex, AuBr ₄ ^– , is present in solution with bands at approximately 105, 197 and 215 cm^–1. However, in these acidic solutions, when the temperature is 50°C or higher, the square planar Au(III) bromide complex is partially transformed into the linear Au(I) bromide complex, AuBr ₂ ^– , with a single band near 208 cm^–1. The transformation of the Au(III) square planar tetrabromo complex into the Au(I) linear dibromo complex is also favored by a reduction of the oxygen fugacity and an increase in pH.     

Kinetic Determination of Mercury(II) at Trace Level from Its Catalytic Effect on a Ligand Substitution Process

A catalytic kinetic method (CKM) is presented for the determination of mercury(II) based on its catalytic effect on the rate of substitution of N-methylpyrazinium ion (Mpz⁺) onto hexacyanoferrate(II). The progress of the reaction was monitored spectrophotometrically at 655 nm by registering the increase in absorbance of the product [Fe(CN)₅(Mpz]²⁻ under the reaction conditions: 5 × 10⁻³ mol L⁻¹ [Fe(CN)₆]⁴⁻), 5 × 10⁻⁵ mol L⁻¹ [Mpz⁺], T = 25.0 ± 0.1°C, pH 5.00 ± 0.02 and ionic strength, I = 0.1 mol L⁻¹ (KNO₃). Quantitative rate data at specified experimental conditions showed a linear dependence of the absorbance after fixed time A _t on the concentration of mercury(II) catalyst in the range 20.06–702.1 ng mL⁻¹. The maximum relative standard deviations and percentage errors for the determination of mercury(II) in the range of 20.06–200.6 ng mL⁻¹ were calculated to be 1.7 and 2.7% respectively. The detection limit was found to be 7.2 ng mL⁻¹ of mercury(II). Accuracy (expressed in terms of recoveries) was in the range of 98–103%. Figures of merit and interference due to many cations and anions was investigated and discussed. The applicability of the method was demonstrated by determining the mercury(II) in different synthetic samples and confirming the results using atomic absorption spectrophotometry. The proposed method allowed determination of mercury(II) in the range 20.06–702.1 ng mL⁻¹ with very good selectivity and an output of 30 samples h⁻¹.__________From Zhurnal Analiticheskoi Khimii, Vol. 60, No. 6, 2005, pp. 654–661.Original English Text Copyright © 2005 by Surendra Prasad.This article was submitted by the author in English.     

Spectrochemical Properties of Noncubical Transition Metal Complexes in Solutions. IX. The Mixed Tetragonal Distorted Bis(Salicylato)Cobalt(II) Complex in Various Solvents

Mixed cobalt(II) complexes with the monodentate ligands: 2-hydroxybenzoic acid deprotonated (sal^–, the salicylate ion) and water, have been investigated. The combined results of the spectrophotometric and conductance measurements, as well as known the X-ray structure for solids, were used to determine the structure of the studied complexes in solution. The electronic absorption spectra in aqueous acid (0.01M HClO₄), ethylene glycol (glycol), formamide (FM), N,N-dimethylformamide (DMF), and dimethyl sulfoxide (DMSO) solutions have been recorded. The d-d electronic spectra have been treated by the crystal-field model (CFM) and angular overlap model (AOM). Low-symmetry splittings of the broad asymmetric bands in the experimental spectra (solutions at room temperature) were found by Gaussian analysis. The effect of the and bonding of the monodentate ligands (with oxygen-donor ligators) on the central metal ion was described in the ligand–field framework. A comparison of the stereochemistry of the complex species in various solutions was made.