Studies on 2-acetylpyridineisonicotinoyl hydrazone complexes of some bivalent 3d-metal ions

2-Acetylpyridineisonicotinoyl hydrazone (Hapinh) complexes of OV(II), Mn(II), Co(II), Ni(II), Cu(II) and Zn(II) having 1:1 metal-ligand stoichiometry have been prepared and characterised by elemental analyses, molar conductance, magnetic susceptibility, electronic, infrared, ESR and NMR (¹H and¹³C) studies. Octahedral/distorted octahedral geometry has been assigned for the OV(II), Mn(II), Ni(II), Cu(II) and Zn(II) complexes while tetrahedral and trigonal bipyramidal configurations have been suggested for the Co (II) adduct and deprotonated complexes respectively. IR and NMR spectral studies suggest a tridentate behaviour of Hapinh and apinh⁻ species in the adducts and deprotonated complexes respectively.     

Synthesis, crystal structure of diferrous complex and its reactivity with dioxygen

The dinuclear complex of [Fe2L{O2P(OPh)2}](CIO4)2 ·Et2O(1) (where L represents the dinucleating ligand N-Et-HPTB, anion of N, N, N', N'-tetrakis (N-ethyl-2-benzimidazolyemethyl)-2-hydroxy-1, 3-diamino-propane) has been synthesized and crystallizes in the triclinic space group P T with cell constants α = 1.526(3) nm, b = 1.259 8(3) nm, c = 1.563 0(3) nm , α = 94.41 (3)°, P = 115.31(3)°, β=99.90(3)°, V= 3.267(1) nm3, z=2, R = 0.084 7 and Rw = 0.177 8. The Fe(Ⅱ) sites are bridged by an alkoxide of the dinucleating ligand and a phosphate, affording a diiron core with an Fe-μ-O-Fe angle of 131.20(3)° and an Fe-Fe distance of 0.364 9 nm. Both Fe(II) centers have trigonal bipyramidal geometry. Dioxygen adduct (1/O2) forms upon exposure of the diferrous complex to O2 at low temperature (-60℃). The 1/O2 adduct is stable at -60℃ but decomposes upon warming. The adduct exhibits visible absorption maximum near 606 nm and resonance Raman features at 478 cm-1 (γFe-o) and 897 cm-1 (γo-o), and the latter     

N,N,N',N'-Tetrabutyladipicamide as a new extractant in toluene of nitric acid and uranium (VI)

N,N,N',N'-Tetrabutyladipicamide (TBAA) was used for the extraction of nitric acid and uranyl(II) ion from nitric acid media into toluene. The effects of nitric acid, uranyl(II) ion, and extractant concentration, temperature and back extraction on the distribution coefficient of uranyl(II) ion have been studied. The main adduct of TBAA and HNO₃ is TBAA·HNO₃ in 1.0 mol/l nitric acid solution. The 1:2:2 complex of uranyl(II) ion, nitrate ion and TBAA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBAA. The values of the thermodynamic parameters have also been calculated.     

Effect of copper(II) ions on the stability of spin adducts formed by the reaction of 5,5-dimethylpyrroline-N-oxide with hydroxyl and hydroxylalkyl radicals

The reactions of copper(II) species with spin adducts formed by reaction of OH·, CH₃CHOH or (CH₃)₂COH with DMPO (5,5-dimethylpyrroline-N-oxide) have been investigated. The spin adducts prepared by -irradiation of appropriate solutions were detected using esr. Copper(II) in the form of aqua, phen, or 1-alanine complexes reacted rapidly with the OH· adduct to give products that gave no esr signal, but with the hydroxylalkyl adducts, reacted to give a new 9-line esr signal, identified as due to the H· adduct, (DMPO-H·). Measurement of the yield of Cu(phen) ₂ ⁺ formed by reaction of the copper(II) complex with the spin adduct showed that approximately 25% of the radiation-produced radicals formed esr detectable spin adducts. The implications of these findings for the use of spin trapping to detect radical intermediates in biological systems is discussed.     

Liquid–liquid extraction of scandium with nalidixic acid in dichloromethane

The extraction behavior of nalidixic acid (HNA) in CH₂Cl₂ has been studied for various di- and trivalent metal ions such as Cu(II), Fe(II), Ni(II), Mn(II), Sb(II), Co(II), Sc(III), Y(III), Nd(III) and Eu(III) from aqueous buffer solutions of pH 1–7 with 0.1 mol dm⁻³ nalidixic acid in dichloromethane. Separation factors of Sc(III) from these metals has shown that its clean separation is possible at pH 3.4–4. The parameters affecting the extraction of Sc(III) were optimized. The composition of the extracted adduct was determined by slope analysis method that came out to be Sc(NA)₃. Extraction of Sc(III) was studied in the presence of various cations and anions. Among the anions studied only fluoride, citrate and oxalate have significant interference whereas, Fe(III) has reduced the extraction to 53% that can be removed by using ascorbic acid as reducing agent. The proposed extraction system proved good stability up to six extraction-stripping stages for the extraction of Sc(III).     

Kinetics and mechanism of oxidation of dimethyl sulphoxide by sodium bromate-sodium bisulphite reagent in aqueous medium

Rates of oxidation of dimethyl sulphoxide (DMSO) by HOBr producedin situ from sodium bromate-sodium bisulphite reagent have been studied iodometrically in aqueous medium. The order in [DMSO] is one when [DMSO] < 001 mol dm^-3, fractional when [DMSO] is between 0.01 and 0.5mol dm^-3 and zero when (DMSO) > 0.5 mol dm^-3. Different rate laws are operative under these three conditions though HOBr is the effective oxidizing species in all the cases. A mechanism involving an intermediate four-membered cyclic transition state between DMSO and HOBr (formation constantK), which decomposes in a slow step with a rate constant(k) has been proposed. Thermodynamic parameters for the adduct formation step and activation parameters for the first-order decomposition of the adduct step have been evaluated in the temperature range 308–323 K. Activation parameters have also been determined while the orders in [DMSO] are unity and zero. The reaction product has been identified as dimethyl sulphone (DMSO₂).     

Study of the activation of molecular oxygen in the presence of manganese(II) complexes

The electronic structures of the systems [Mn(phen)₂]²⁺ (I), Mn(HCO₃ ⁻)₂(H₂O)₃ (II), [Mn(phen)₂(H₂O)O₂]²⁺ (III) and [Mn(phen)₂O₂]²⁺ (IV) have been calculated by the IEHM method. The change in the energy barrier for the activation of O₂ (−4.59 eV (III), −4.69 eV (IV) for the elementary step has been calculated using the vibronic activation theory. The formation of an adduct of molecular oxygen with II is shown to be unlikely. Deceased. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 3, pp. 192–195, May–June, 1997.     

N,N,N′,N′-tetrabutylmalonamide as a new extractant for extraction of nitric acid and uranium(VI) in toluene

N,N,N,N-tetrabutylmalonamide (TBMA) was synthesized and used for extraction of uranyl(II) ion from nitric acid media in toluene. The effects of nitric acid concentration, extractant concentration, temperature and salting-out agent (LiNO₃) on distribution coefficients of uranyl(II) ion have been studied. The extraction of nitric acid is also studied. The main adduct of TBMA and HNO₃ is HNO₃. TBMA in 1.0 mol/l nitric acid solution. The 1:2:3 complex of uranyl(II) ion, nitrate ion and TBMA as extracted species is further confirmed by IR spectra of the extraction of uranyl(II) ion with TBMA, and found that the NO ₃ ^– in the extraction species UO₂(NO₃)₂·3TBMA did not participate in coordination of uranyl(II) ion. The values of thermodynamic parameters have also been calculated.     

Structure and magnetic properties of 2,4,6,8-tetra(<Emphasis Type="Italic">tert</Emphasis>-butyl)phenoxazin-1-one adducts with cobalt(II) salts

Complex formation reaction of redox-active 2,4,6,8-tetra(tert-butyl)phenoxazin-1-one with cobalt(II) chloride leading to the dimeric adduct has been studied. UV spectroscopy studies have revealed the equilibrium of the formed adduct with dissociated form of the complex in the acetonitrile solution. In the presence of ethylene glycol, the complex formation with cobalt(II) perchlorate has afforded the high-spin trimolecular adduct. Crystal structure of the obtained adducts has been studied by means of X-ray diffraction analysis.     

Synthesis,spectral, and antifungal studies of transition metal complexes with sixteen-membered hexadentate macrocylic ligand

A novel hexadentate nitrogen donor [N₆] macrocyclic ligand viz, 1,5,11,15,21,22-hexaaza-2,14-dimethyl-l4,12-diphenyltricyclo[15.3.1.I(7–11)]docosane[1,4,6,8,10(22)-11,14,16,18,20(21)]decaene (L), has been synthesised. The Co (II), Ni (II), and Cu (II) complexes with this ligand have been prepared and subjected to elemental analysis, molar conductance, magnetic susceptibility measurements, mass, ¹H NMR (ligand), IR, electronic, and ESR spectral studies and electrochemical investigation. On the basis of molar conductance the complexes can be formulated as [M(L)]X₂ (where M = Co (II), Ni (II), Cu (II) and X = Cl⁻ and NO₃⁻) due to their 1: 2 electrolytic nature in DMSO. All the complexes are of the high-spin type and are six-coordinated. On the basis of IR, electronic, and ESR spectral studies, an octahedral geometry has been assigned for the Co(II) and Ni(II) complexes, whereas a tetragonal geometry for the Cu(II) complexes was found. Antimicrobial activity of L and its complexes as growth inhibiting agents have been screened in vitro against two species (F. moniliformae and R. solani) of plant pathogenic fungi. The text was submitted by the authors in English.     

Mechanisms for negative reactant ion formation in an atmospheric pressure corona discharge

In an effort to better understand the formation of negative reactant ions in air produced by an atmospheric pressure corona discharge source, the neutral vapors generated by the corona were introduced in varying amounts into the ionization region of an ion mobility spectrometer/mass spectrometer containing a ⁶³Ni ionization source. With no discharge gas the predominant ions were O₂ ⁻, however, upon the introduction of low levels of discharge gas the NO₂ ⁻ ion quickly became the dominant species. As the amount of discharge gas increased the appearance of CO₃ ⁻ was observed followed by the appearance of NO₃ ⁻. At very high levels, NO₃ ⁻ species became effectively the only ion present and appeared as two peaks in the IMS spectrum, NO₃ ⁻ and the NO₃ ⁻·HNO₃ adduct, with separate mobilities. Since explosive compounds typically ionize in the presence of negative reactant ions, the ionization of an explosive, RDX, was examined in order to investigate the ionization properties with these three primary ions. It was found that RDX forms a strong adduct with both NO₂ ⁻ and NO₃ ⁻ with reduced mobility values of 1.49 and 1.44 cm²V⁻¹ s⁻¹, respectively. No adduct was observed for RDX with CO₃ ⁻ although this adduct has been observed with a corona discharge mass spectrometer. It is believed that this adduct, although formed, does not have a sufficiently long lifetime (greater than 10 ms) to be observed in an ion mobility spectrometer.     

Influence of reactant structure on composition and stability of adducts of bis-macrocyclic complexes of copper(II) with aliphatic α,ω-diamines

On the basis of spectrophotometric measurements, constants have been determined for adduct formation between bis-macrocyclic complexes of copper(II) and aliphatic diamines. For these systems, the influence of reactant structure on the specific features of complexation has been established. L. V. Pisarzhevskii Institute of Physical Chemistry, National Academy of Sciences of the Ukraine, 31 Nauka Prospect, Kiev 252039, Ukraine. Translated from Teoreticheskaya i éksperimental’naya Khimiya, Vol. 33, No. 2, pp. 83–87, March–April, 1997.     

Extraction of zirconium(IV) from hydrochloric acid solutions by tri-octylamine and neutral donors

Solvent extraction of Zr(IV) from aqueous HCl solutions by mixtures of TOA and different organophosphorous bases in carbontetrachloride solvent have been found to be always higher than that by any single extractant. Synergism has been observed in the range of 2.4–9.6M HCl. Although the species extracted with neutral donor alone seems to be ZrCl₄·TOPO etc, with a mixture of extractants, however, the extracted species appears to be Q₂ZrCl₆·TOPO where Q is R₃NH. The extraction has also been found to increase with increase in the concentration of amines and neutral donors. Enhancement of extraction has been explained by the formation of a complex adduct in organic phase. Synergistic coefficients and apparent formation constants of the complex adducts have also been calculated.     

Preconcentration and determination of trace amounts of lead (II) as thenoyltrifluoroacetone complex with dibenzo-18-crown-6 by synergistic extraction and atomic absorption spectrometry

A new method for the preconcentration and determination of trace amounts of lead at the μg/L level in natural waters has been established based on the formation of the thenoyltrifluoroacetone (TTA) complex with dibenzo-18-crown-6 (DB18C6) by means of synergistic extraction and back-extraction combined with atomic absorption spectrometry (AAS). The effect of various factors (synergism with TTA and DB18C6, shaking time, preconcentration factor, composition of the extracted species, and foreign ions etc.) on the extraction and back-extraction of lead has been investigated in detail. The lead-TTA chelate in o-dichlorobenzene forms a stable adduct with DB18C6 as Pb(TTA)₂ DB18C6. The stability constant (β) of the adduct determined by curve fitting method was log β = 4.2. The amount of lead in natural waters such as tap water (Kanazawa University) and Kakehashi river (Komatsu City) determined by the present method was found to be 0.64 ± 0.02 μg/L and 5.10 ± 0.03 μg/L, respectively. Received: 14 July 1997 / Revised: 3 November 1997 / Accepted: 20 January 1998     

Complexes of Uracil (2,4-Dihydroxypyrimidine) Derivatives

Equilibrium studies have been carried out on complex formation of M²⁺ ions (M=Co, Ni, and Zn) with L = thymine, 6-chloromethyluracil, 5-hydroxymethyluracil, uracil, 6-methyluracil, and 6-umpm (dimethyl 6-uracilmethylphosphonate) in aqueous solution, at 25 ^∘;C and an ionic strength of I=0.1 mol⋅L⁻¹ (KNO₃). Potentiometric results indicate the formation of ML species (coordination via N3) for Co(II) and Ni(II) as well as a hydroxo complex MLH₋₁—with a deprotonated water of the inner coordination sphere. Titrations of Zn(II) confirmed both the existence of ML and MLH₋₁ species with 6-chloromethyluracil as well as 5-hydroxymethyluracil, whereas for uracil, thymine, and 6-methyluracil the only species accepted pH-metrically was MLH₋₁. For all the ligands under study the complexation with Zn(II) was reinvestigated by means of ion-selective electrodes (ISE). The role of substituents is discussed.     

Synthesis,structural characterization,and antibacterial studies of a tetradentate macrocyclic ligand and Its Co(II), Ni(II), and Cu(II) complexes

A novel macrocyclic tetradentate ligand 1,5,8,12-tetraaza-2,4,9,11-tetraphenyl-6,7:13,14-dibenzocyclohexadeca- 1,4,8,11-tetraene (L) has been synthesized. Cobalt(II), nickel(II), and copper(II) complexes of this ligand have been prepared and characterized by elemental analysis, molar conductance measurements, magnetic susceptibitity measurements, and mass, IR, electronic, and ESR spectral studies. The molar conductance measurements correspond to a nonelectrolytic nature for all the complexes, which can be formulated as [M(L)X₂] (where M = Co(II), Ni(II), and Cu(II); X = Cl⁻ and NO₃⁻). On the basis of IR, electronic, and ESR spectral studies, an octahedral geometry has been assigned to the Co(II) and Ni(II) complexes, whereas a tetragonal geometry was found for the Cu(II) complexes. The investigated compounds and uncomplexed metal salts and the ligands were tested against bacterial species like Sarcina lutea, Escherchia coli, and Staphylococcus aureus. The metal complexes have higher activity than the free ligand and metal salts. The text was submitted by the authors in English.     

Solvent and steric effects on the extraction of copper(II) with pivalic acid

The solvent extraction of copper(II) with trimethylacetic acid using benzene and 1-octanol as solvents was performed at 25 degrees C and 0.1 mole. dm(-3) ionic strength in the aqueous phase. In contrast to the extraction of copper(II) with a saturated straight-chain carboxylic acid in benzene, the dimeric copper(II) trimethylacetate was observed to dissociate into the monomer, even at a moderately high concentration of copper(II) in the benzene phase. In the system using 1-octanol as a solvent, both the monomeric and dimeric copper(II) species are suggested to be solvated by some 1-octanol molecules. It has been found that the dimerization and adduct formation of copper(II) species in benzene may more effectively enhance the extractability of copper(II) than the solvation by 1-octanol molecules.     

Interaction between poly(N-vinylpyrrolidone) and poly(acrylic acid)s: Influence of hydrogen and cupric ions on the adduct formation

Interpolymer adduct formation between poly(N-vinylpyrrolidone) (PVP) and poly(methacrylic acid) (PMAA) is mainly due to hydrogen bonding. It is found that the interpolymer adduct formation is enhanced in the presence of Cu(II). A simple turbidity measurement making use of a spectrophotofluorometer is described for the study of the interpolymer adduct formation. Enhanced adduct formation in the presence of Cu(II) is described by the empirical relation d[PAd]/D[PVP] = k × 10^4α[Cu(II)]^α, where PAd represents the interpolymer adduct and α and k are constants. Similar results have been obtained in the case of interpolymer adduct formation between poly(acrylic acid) (PAA) and PVP. In the above expression α signifies the influence of chelation on Cu(II)–PAA/PMAA–PVP-type complex formation and k is the extent of PVP–PAA/PMAA interaction. The enhancement of adduct formation in the presence of Cu(II) is more in PAA than in PMAA. Turbidity and viscosity measurements further indicate that the influence of Cu(II) on interpolymer adduct formation between PVP and PMAA or PAA is more in the case of PAA than PMAA, as PAA is a better chelating ligand. But the extent of adduct formation is more in the case of PMAA in the absence of Cu(II) ions due to hydrophobic interactions exerted by methyl groups.     

Study on the Heck reaction promoted by carbene adduct of cyclopalladated ferrocenylimine and the related reaction mechanism

Carbene adduct of cyclopalladated ferrocenylimine has been successfully applied to Heck reaction of various aryl bromides with olefins. On the basis of kinetic studies, in situ ¹³C NMR spectra investigations and Hg poisoning experiments, it was proposed that the Heck reaction catalyzed by carbene adduct of cyclopalladated ferrocenylimine proceeded through a classical Pd(0)/Pd(II) cycle and such palladacycle was only a reservoir of the catalytically active Pd(0) species.