Synthesis and spectroscopic studies of some new metal carbonyl derivatives of 1-(2-pyridylazo)-2-naphthol

Interaction of 1-(2-pyridylazo)-2-naphthol (PAN) with [Mo(CO)₆] in air resulted in formation of the tricarbonyl oxo-complex [Mo(O)(CO)₃(PAN)], 1. The dicarbonyl complex [Ru(CO)₂(PAN)], 3, was obtained from the reaction of [Ru₃(CO)₁₂] with PAN. In presence of triphenyl phosphine (PPh₃), the reaction of PAN with either Mo(CO)₆ or Ru₃(CO)₁₂ gave [Mo(CO)₃(PAN)(PPh₃)], 2, and [Ru(CO)₂(PAN)(PPh₃)], 4. All the complexes were characterized by elemental analysis, mass spectrometry, IR, and NMR spectroscopy. The thermal properties of the complexes were also investigated by thermogravimetry.     

Synthese und Eigenschaften der heteronuklearen Metallatomcluster Re4(CO)12[μ3-GaRe(CO)5]4 und Re2(CO)3[μ-GaRe(CO)5]2

Synthesis and Properties of Heteronuclear Metal Atom Clusters Re₄(CO)₁₂[μ₃-GaRe(CO)₅]₄ and Re₂(CO)₈[μ-GaRe(CO)₅]₂ The title compounds were prepared by the reaction of gallium halides and dirhenium decacarbonyl. Crystals of the four-membered cluster Re₂(CO)₈[μ-GaRe(CO)₅]₂ gave at 300⁰C with aggregation of four Re atoms to an inner Re₄ tetrahedron the product Re₄(CO)₁₂(CO)[μ₃-GaRe(CO)₅]₄and with Ga₂I₃ shown by mass spectroscopic measurements the molecule ion Re₄(CO)₁₆+. In tetra-hydrofuran solution the cluster Re₄(CO)₁₂[μ₃-GaRe(CO)₅]₄ and the hydride Li[C₂H₅)₃BH] have formed the formyl complex Li₄{Re₄(CO)₁₂[μ₃ -GaRe(CO)₄(CHO)] ₄}, which was estimated by ¹H n. m. r. and i. r. spectroscopic data. Both synthesized gallium rhenium carbonyl clusters were characterized by i.r. spectroscopic measurements. The comparison of these results with those of the structurally known indium rhenium carbonyl clusters led to proposals of the molecule structure of the analogous gallium rhenium compounds.     

Selective extraction of thallium(III) in the presence of gallium(III), indium(III), bismuth(III) and antimony(III) by salting-out of an aqueous mixture of 2-propanol

Thallium(III), in the presence of other triply charged ions such as gallium, indium, bismuth and antimony in aqueous solution, was quantitatively and selectively extracted into 2-propanol/water phase by addition of NaCl ranging from 2.5 to 4.0 mol dm⁻³. The extraction efficiencies of gallium, indium, bismuth and antimony were much lower than that of thallium(III). Thus a maximal selective separation of thallium(III) from these elements could be attained using a 2-propanol/water mixture. Thallium(III) was extracted as TlCl₄⁻ with Na⁺. The detailed extraction mechanism in the presence of chloride, water in the organic phase and counter ions is discussed.     

Sensitive spectrophotometric determination of La(III) with 1-(2-pyridylazo)-2-naphthol

A simple and sensitive method for spectrophotometric determination of lanthanum has been developed. At pH 9.6, in presence of 50% ethanol, lanthanum reacts with 1-(-2-pyridylazo)-2-naphthol (PAN) to form a red complex which has two absorption maxima, at 545 and 510 nm. The molar absorptivity at 545 nm is 0.55 × 10⁴ liters · mol^?1 cm^?1. On the other hand, lanthanum reacts with PAN in pure ethanol to form a red complex at 530 nm, with high molar absorptivity (8 × 10⁴ liters · mol^?1 cm^?1).     

Indium determination in different environmental materials by electrothermal atomic absorption spectrometry with Amberlite XAD-2 coated with 1-(2-pyridylazo)-2-naphthol

Methods were developed for indium (In) determination in complex ores by electrothermal atomization atomic absorption spectrometry using matrix modification after its separation with Amberlite XAD-2 coated with 1-(2-pyridylazo)-2-naphthol (PAN). Palladium-magnesium, nickel, and zinc nitrates were used as matrix modifiers and were compared in terms of maximum pyrolysis temperature, sensitivity and background signal. They have enhanced the absorption signals for indium, respectively eliminating the matrix interferences. The standard additions method was applied. The relative standard deviations for six replicate determinations were in the range 0.3-4.0% for indium in different ores samples for indium concentrations 7.6-209 μg g⁻¹. The recommended method was applied to the indium determination in real samples. The data obtained by this method were in good agreement with those obtained by ICP-AES.     

Complexes of organolead and organotin ions with 1-(2-pyridylazo)-2-naphthol

The stability constants of the complexes of 1-(2-pyridylazo)-2-naphthol with several organotin and lead ions were determined spectrophotometrically in aqueous 20% (v/v) dioxane and were shown to have very high values. The extraction of the complex of (C₂H₅)₂Pb²⁺ from water into chloroform was studied, and the formation of an extractable (C₂H₅)₂Pb(PAN)(OH) complex is postulated.     

Novel Complexes of Gallium(III), Indium(III), and Thallium(III) with Pyridine‐Containing Proton Transfer Ion Pairs Obtained from Dipicolinic Acid – Synthesis,Characterization and X‐ray Crystal Structure

Three new complexes of group thirteen metals, gallium(III), indium(III), and thallium(III) with proton transfer compounds, obtained from 2,6‐pyridinedicarboxylic acid (dipicolinic acid), were synthesized and characterized using elemental analysis, IR, ¹H and ¹³C NMR spectroscopy and single crystal X‐ray diffraction. The gallium(III) and indium(III) complexes were prepared using (pydaH₂)(pydc) (pyda = 2,6‐pyridinediamine, pydcH₂ = dipicolinic acid) and thallium(III) complex was obtained from (creatH)(pydcH) (creat = creatinine). The chemical formulae and space groups of the complexes are (pydaH)[Ga(pydc)₂] · 3.25H₂O · CH₃OH, ( 1 ), [In(pydc)(pydcH)(H₂O)₂] · 5H₂O, Pna2₁ ( 2 ) and [Tl₂(pydcH)₃(pydc)(H₂O)₂], ( 3 ). Non‐covalent interactions such as ion‐pairing, hydrogen bonding and π‐π stacking are discussed. The complexation reactions of pyda, pydc, and pyda + pydc with In³⁺ and Ga³⁺ ions in aqueous solution were investigated by potentiometric pH titrations, and the equilibrium constants for all major complexes formed are described.     

Co-microprecipitation/flotation of trace amounts of cadmium from environmental samples through its complexation with iodide and neutralization with cetyltrimethylammonium bromide in the presence of perchlorate ions

ABSTRACT

A fast, cost-effective and reliable method is presented for separation and preconcentration of trace amounts of cadmium based on co-precipitation and flotation prior to its flame atomic absorption (AAS) spectrometric determination. Cadmium (II) was complexed with iodide and neutralized with cetyltrimethylammonium bromide (CTAB) in the presence of perchlorate ions. This resulted in the formation of a bulky precipitate containing the ternary complex of CdI₄(CTA)₂, floating on the top of the solution. The aqueous layer was then simply drained out, the floated layer was dissolved in 1.0 mL of acetonitrile, and its Cd content was determined by flame atomic absorption spectrometry. The parameters affecting the designed separation method such as KI, CTAB, and ClO₄^? concentration, pH, ionic strength, volumes of sample and dissolving solvent, and extraction time were studied and optimized. For preconcentration of 200 mL of the sample, the calibration graph was linear in the range of 1–30 μg L^?1 of cadmium with a correlation coefficient of 0.9997, enhancement factor of 194 and a limit of detection of 0.18 μg L^?1. The relative standard deviation for seven replicate determinations at 20 μg L^?1 levels of cadmium was found to be 2.1%. The effect of the presence of different common cations and anions on the separation and determination of Cd(II) by the developed method was studied. The method was successfully applied to the determination of trace amounts of Cd(II) ions in different types of real samples including tap water, polluted industrial wastewater, dust, and soil with the recoveries in the range of 95.3 to 103.4.     

Formation of mixed complexes in the extraction of indium with 1-(2-pyridylazo)-2-naphthol

A detailed study has been made of the extraction of indium into chloroform by 1-(2-pyridylazo)-2-naphthol (PAN). The rate of extraction is maximal if the PAN is added to the aqueous phase and is not added as its chloroform solution. The ratio of indium to PAN is 1:1 and the cationic complex can be extracted only if a suitable anion is present, such as acetate or chloride.     

[Mo4O4(μ-S)4(μ-OH)2(μ-H2O)(H2O)2(pba)]2−: An Original Coordination Mode for the Ligand 1,3-Propylenebis(Oxamate)

The novel polyoxothioanion [Mo₄S₄O₄(OH)₂(OH₂)₃pba]^2? where pba^4? ligand is the 1,3-propylenebis(oxamate), was prepared by reacting Mo₁₂S₁₂O₁₂(OH)₁₂(OH₂)₆ ring with [Cu-pba]^2? in aqueous medium. NaK[Mo₄O₄(μ-S)₄(μ-OH)₂(μ-H₂O)(H₂O)₂(pba)] ·7H₂O was isolated in the solid state and fully characterized by X-ray diffraction study (tetragonal, P4(2)/m [a=20.4962(4) Å; b=20.4962(4) Å; c=14.7013(5) Å). The molecular structure consists of an arc cycle shape tetranuclear enchainment {Mo₄S₄O₄(OH)₂ (OH₂)₃} closed by a pba^4? ligand. The 3-D packing, resulting from the connection between K⁺ and Na⁺ and the coordination complex {Mo₄-pba]^2? is described. The ¹H-NMR characterization of the complex in aqueous solution is given. The ¹H-NMR spectrum exhibits four signals assigned to four enantiotopic protons of the alkyl chain of the pba^4? ligand and is in agreement with crystal structure of the complex [Mo₄-pba]^2?. The compound was also characterized by infrared spectroscopy.     

A new series of oxofluorovanadates (IV) of the type [VOF3(H2O)]−

Four salts of a new series of the type LH[VOF₃(H₂O)] (where L = pyridine,2,6,-lutidine, 2,2′-bipyridyl and 1,10-phenanthroline) have been isolated by crystallising solutions of the bases in aqueous hydrofluoric acid with VOSO₄·3H₂O. A dinuclear complex, pyH[(VO)₂F₅] and two nonelectrolytes, [VOF₂(bipy)] and [VOF₂(phen)] have also been prepared by the pyrolysis of the corresponding salts of [VOF₃(H₂O)]. The molecular conductances of dilute aqueous solutions of the salts are very high indicating appreciable decomposition, whereas the molecular conductances of [VOF₂(bipy)] and [VOF₂(phen)] in nitrobenzene are practically zero. The magnetic moments of the salts and the nonelectrolytes are almost equal to the spin-only value for one electron. The dinuclear complex pyH[(VO)₂F₅] is, however, much weakly paramagnetic (μ_eff = 1.33 BM). The i.r. spectra of all the complexes show very strong terminal VO bands between 980-940 cm^-1. The spectrum of pyH[(VO)₂F₅] gave no bands between 950-750 cm^-1 indicating the absence of bridging VO group.     

Indium-HI-mediated one-pot reaction of 1-(2-arylethynyl)-2-nitroarenes to 2-arylindoles

While 1-(2-arylethynyl)-2-nitroarenes were reduced to 2-(2-arylethynyl)anilines in the presence of indium and InCl₃ in THF/H₂O (v/v = 5/1) at 50 °C, 1-(2-arylethynyl)-2-nitroarenes were reductively cyclized to 2-arylindoles with good yields in the presence of indium and aqueous HI in benzene.     

Determination of manganese by flame atomic absorption spectrometry after its adsorption onto naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN)

A system for determination of manganese, after preconcentration with 3% (w/w) 1-(2-pyridylazo)-2-naphthol (PAN), adsorbed on microcrystalline naphthalene is proposed. An amount of 200 mg of this complexing mixture is placed in a glass column and conditioned with a NH₄Cl/NH₄OH buffer solution (pH 9.5). The aqueous sample, containing manganese, is treated with an ammonium tartrate solution, then with a hydroxylammonium chloride solution and, finally, with a buffer solution. The resulting solution is passed through the column containing microcrystalline naphthalene modified with 1-(2-pyridylazo)-2-naphthol (PAN) where Mn(II) is retained. The column is first washed with deionized water and then with 10.0 ml of dimethylformamide to dissolve the Mn(II)-PAN/naphthalene complex. Manganese is determined by air-acetylene flame atomic absorption spectrometry. About 1 μg of manganese can be concentrated from 200 ml of aqueous sample, allowing a preconcentration factor of 20, a limit of quantification of 5 ng ml⁻¹ and R.S.D. of 3.8%. The accuracy was ascertained using certified reference materials, including samples of urine and glass. Water samples were also analysed and the results are in good agreement with those obtained by graphite furnace atomic absorption spectrometry.     

Evaluation of the fuel cell performances of TiO2/PAN electrospun carbon-based electrodes

Electrocatalytic effect of the untreated and TiO₂+polyacrylonitrile (PAN) modified discarded battery coal (DBC) and pencil graphite electrodes (PGE) were evaluated in fuel cell (FC) applications. TiO₂+PAN solution is coated on PGE and DBC electrodes by electrospinning. According to the FESEM and EDS characterizations, TiO₂ and PAN nanofibers are found to be approximately 40 and 240 nm in size. TiO₂+PAN/PGE showed the best FC performances with 2.00 A cm^–2 current density and 5.05 W cm^–2 power density values, whereas TiO₂+PAN/DBC showed 0.68 A cm^–2 current density and 0.62 W cm^–2 power density values. Electrochemical characterizations of PGE and TiO₂+PAN/PGE electrodes were investigated by cyclic voltammetry and electrochemical impedance spectroscopy. Finally, long-term FC measurement results of developed electrodes exhibited very reasonable recovery values. Along with the comparison of the electrode performances, the recovery of DBCs as electrodes for renewable energy production has been achieved.     

Copper complexes of 1-[(2-carboxyethyl)benzene]-3-[2-pyridine]triazene

The triazenide, 1-[(2-carboxyethyl)benzene]-3-[2-pyridine]triazene (HL), has been synthesized. In the presence of Et₃N, the reaction of HL with Cu(OAc)₂·H₂O or CuCl₂·2H₂O gives the tetranuclear copper(II) complexes {Cu₄(L)₂(μ₂-OH)₂(OAc)₄} 1 and {Cu₄L₄(μ₄-O)Cl₂} 2, respectively. The X-ray crystal structures of both complexes have been obtained. Magnetic studies indicate significant antiferromagnetic coupling between the copper(II) centers for both complexes, with coupling constants (J) of −493.4 cm⁻¹ for 1 and −165 cm⁻¹ for 2.     

Far-infrared studies of Cu(II)—1-(2 pyridylazo)-2-naphthol complexes by metal isotope technique

The metal isotope technique is applied to the investigation of the metal—ligand bands in the i.r. spectra of complexes of type: Cu(PAN)X and Cu(PAN)₂ where X = Cl, Br and PAN symbolizes 1-(2-pyridylazo)-2-naphthol. For the Cu(PAN)Cl complex, bands at 337, 274 and 196 cm⁻¹ were assigned to the CuO, CuNpy and CuNazo stretching vibrations, respectively. Two CuCl stretching vibrations have been found at 298 and 236 cm⁻¹. The spectrum indicates that in the Cu(PAN)₂ complex, PAN acts as a bidentate ligand as only CuO and CuNazo bonds are formed.     

2-(2-Hydroxy-4-methoxybenzoyl)benzoic acid derivatives of Group 4 metal alkoxides

Continued exploration of the coordination behavior of derivatives of 2-benzophenone-based ligands with metal alkoxides ([M(OR)₄]) was undertaken from the reaction of 2-(2-hydroxy-4-methoxybenzoyl)benzoic acid (H₂-OBzA) with a series of Group 4 precursors. The products of these reactions were identified as: [(OR)₂Ti(μ-(c,c-OBzA))]₂ (OR?=?OCHMe₂ (OPrⁱ; 1 ?2tol); OCMe₃ (OBu^t; 2 ?THF); OCH₂CMe₃ (ONep; 3)), [[(OPrⁱ)₃Ti(μ-OPrⁱ)Ti(OPrⁱ)₂]₂(μ-(μ_c,μ-OBzA))₂]₂ (4), [(ONep)₃Zr(μ-ONep)₂Zr(ONep)₂]₂(μ-(c,μ-OBzA)₂) (5 ?tol), [(py)(OBu^t)₃Zr]₂(μ-(c,c-OBzA)) (6), [(OBu^t)₂Hf(μ-OBu^t)]₂(μ-(c,η¹-OBzA)) (7) where ‘c’?=?chelating or η²; ‘μ’?=?bridging or η¹,η¹(O,O’); and μ_c?=?bridging chelating or η¹,η¹(O,O’); η^2?:?η¹. The metal centers for each of these compounds adopt a pseudo-octahedral geometry employing the OBzA ligand in numerous binding modes. The different functional oxygens (carboxylate, hydroxyl, and carbonyl) were employed in a variety of coordination modes for 1–7. The complexity of these OBzA-modified compounds is driven by a combination of the coordination behavior of the OBzA moieties, the size of the metal cation, and the pendant chain of the OR ligand. Solution NMR indicates a complex structure exists in solution that was considered to be consistent with the solid-state structure.     

Seven-coordinate rhenium(III) complexes of 1-(2-pyridylazo)-2-naphtholate: X-ray studies,spectroscopic characterization and DFT calculations

The reactions of [ReX₃(MeCN)(PPh₃)₂] (X = Cl or Br) with 1-(2-pyridylazo)-2-naphthol (HPAN) have been examined and the [ReBr(PAN)₂] · 2CHCl₃ (1) and [ReCl(PAN)₂] (2) complexes have been obtained. The both complexes have been structurally and spectroscopically characterized, and compound 1 has been additionally studied by magnetic measurements. The magnetic behavior is characteristic of mononuclear seven-coordinated Re(III) complex with d⁴ low-spin configuration, which gives diamagnetic ground state.     

Spectrophotometric and solvent extraction study of o-hydroxybenzaldehyde isonicotinoyl hydrazone complexes with gallium and indium

Complex formation of o-hydroxybenzaldehyde isonicotinoyl hydrazone with Ga^III, In^III and Tl^III has been studied. The thallium complex is unstable. The composition and the instability constants of gallium and indium complexes were determined. Molar absorptivity of gallium complex at 390 nm is 3.40 × 10⁴ and that of indium at 380 nm is 3.20 × 10⁴ l mole^?1 cm^?1. Both complexes were found to be rapidly and quantitatively transfered into 1-pentanol. The corresponding aluminum complex is not extracted. Possible analytical application for separation and spectrophotometric determination of these elements is also examined.