Kinetic effect of zinc(II) and cadmium(II) ions on configurational inversion of deltaLLL-fac(S)-tris(L-cysteinato-N,S)cobalt(III) complex.

It has been confirmed from circular dichroism (CD) spectral changes of aqueous solutions of deltaLLL-fac(S)-[Co(L-cys-N,S)3]3- that the absolute configurational inversion to the ALLL isomer is remarkably accelerated by zinc(II), while it is retarded by cadmium(II). In the diluted solutions of these metal ions containing excess deltaLLL-fac(S)-[Co(L-cys-N,S)3]3-, the observed inversion rate constant linearly depends on the zinc(II) concentration with an intercept, while it is not affected by the cadmium(II) concentration. The kinetic behavior has been explained by difference between zinc(II)- and cadmium(II)-interactions with lone pairs on sulfur donor atoms of fac(S)-[Co(L-cys-N,S)3]3-. It has also been proposed that concentrations of zinc(II) and cadmium(II) can be simultaneously determined by the kinetic measurements.     

Bis(methoxo)titan(IV)-dichlorid

Bis(methoxo)titanium(IV) Dichloride [CH₃O]₂TiCl₂ has been prepared by reaction between TiCl₄ and methanol. It has been characterized by different methods.     

Polarographic determination of osmium with the osmium(VIII)-cerium(IV)-arsenic(III) system

A highly sensitive and novel polarographic method has been developed for determination of ultratrace amounts of osmium, based on the catalysis of the cerium(IV)-arsenic(III) reaction by osmium(VIII). The reaction rate is monitored by measuring the arsenic(III) with a single-sweep oscillopolarograph. Osmium concentrations from 7.0 x 10(-11) to 5.0 x 10(-9)M can be determined by the initial rate method. The method has been applied to determination of osmium in refined ore and chlorination residues with satisfactory results.     

Extraction and separation of (137)cs and (86)rb by means of 4-t-butyl-2(alpha-methylbenzyl)phenol

The extraction of caesium-137 and rubidium-86 by a solution of 4-t-butyl-2(alpha-methylbenzyl)phenol in n-octane and tetrachloromethane has been investigated. The separation of rubidium and caesium has been performed by the Craig method and by reversedphase extraction chromatography.     

Extraction chromatographic study of aluminium(III) and mutual separation of aluminium(III), gallium(III), indium(III) and thallium(III) with N-n-octylaniline

A selective method has been developed for extraction chromatographic studies of aluminium(III) and its separation from several metal ions with a chromatographic column containing N-n-octylaniline (liquid anion exchanger) coated on silanized silica gel as a stationary phase. The aluminium(III) was quantitatively extracted with the 0.065 mol/L N-n-octylaninine from 0.013 to 0.05 mol/L sodium succinate at a flow rate of 1.0 mL/min. The extracted metal ion has been recovered by eluting with 25.0 mL of 0.05 mol/L hydrochloric acid and estimated spectrophotometrically with aurintricarboxylic acid. The effects of the acid concentration, the reagent concentration, the flow rate and the eluting agents have been investigated. The log-log plots of distribution coefficient (KdAl(III)) versus N-n-octylaniline concentrationin 0.005 and 0.007 mol/L sodium succinate gave theslopes 0.5 and 0.7 respectively and showed theprobable composition of theextracted species was 1:1 (metal to amine ratio) and the nature of extracted species is [RR''NH2+ Al succinate2-] org. .The extraction of aluminium(III) was carried out in the presence of various ions to ascertain the tolerance limit of individual ions. Aluminium(III) has been separated from multicomponent mixtures, pharmaceutical samples and synthetic mixtures corresponding to alloys. A scheme for mutual separation of aluminium(III), indium(III), gallium(III) and thallium(III) has been developed by using suitable masking agents. The method is fast, accurate and precise.     

Metal exchange reaction between Mg(II) and Cd(II) octa(4-bromophenyl)tetraazaporphyrinates with manganese(II) chloride in dimethylformamide

Reaction of metal exchange of Mg(II) and Cd(II) octa(4-bromophenyl)tetraazaporphyrinates with MnCl₂ in dimethylformamide has been studied by means of spectrophotometry. Kinetic parameters of the reaction have been determined; the reaction stoichiometry mechanism has been suggested.     

Acid-base properties of bis(hydrazinocarbonylmethyl) sulfoxide and its complex formation with copper(II) and nickel(II)

Behavior of physiologically active compound, bis(hydrazinocarbonylmethyl) sulfoxide, in aqueous solution has been studied by means of potentiometry, spectrophotometry, and mathematical simulation. Protolytic properties of bis(hydrazinocarbonylmethyl) sulfoxide have been described, and the formation of sodium salt has been confirmed. Composition and stability constants of bis(hydrazinocarbonylmethyl) sulfoxide complexes with copper(II) and nickel(II) have been determined, and the complexes structures have been simulated by molecular mechanics method.     

Preparation and characterization of bis(acetonitrile)bis(acetylacetonato)technetium(III)

A new chemical species of bis(acetonitrile)bis(acetylacetonato)technetium(III), [Tc(acac)₂(CH₃CN)₂]⁺, has been prepared by the reaction of tris(acetylacetonato)technetium(III) with acetonitrile in the presence of a strong acid, perchloric or hydrochloric acid. The reaction kinetics were followed by observing spectral change of Tc(acac)₃ in the UV-visible region. The complex has been characterized by combination of elemental analyses, IR and UV-visible spectrophotometry, ion-exchange chromatography, and paper electrophoresis. Applicability of this substance to synthesize mixed-ligand technetium(III) complexes was discussed based on the solubility of this complex and the ease of substitution of the acetonitrile ligand.     

The Synthesis and Structure of (1-(Diphenylphosphino)-1 - (Phenylthio)Ferrocene)Tricarbonyliron(O) (ptppf)Fe(CO)3

The complex (ptppf)Fe(CO)₃ has been prepared in high yield by the reaction of ptppf, l-(diphenyl-phosphino)-l'-(phenylthio)ferrocene, with (cis-cyclooctene)₂-Fe(CO)₃ in THF at ?60°C. The complex has been characterized by IR, ³¹P NMR, mass spectrometry and single-crystal X-ray diffraction. This compound is the first example of a ferrocenyl ligand having both sulfur and phosphorus donor atoms bound to a Fe(CO)₃ moiety. X-ray crystallography shows that the two cyclopentadienyl rings are approximately eclipsed, a rotation of 13° from exactly eclipsed conformation. The tricarbonyl iron center has a trigonal bipyramidal geometry with sulfur occupying the equatorial site and phosphorus the axial site. Crystals of (ptppf)Fe(CO)₃ are monoclinic, with a = 11.645(2), b = 14.304(1), c = 17.075(2) Å,β = 109.23(3)°, Z = 4, and space group P 2₁/n. The structure was solved according to the heavy-atom method and refined by full-matrix least-squares procedures to R = 0.037 for 2098 reflections with I ≥ 2.5σ(I).     

Structure,cyclic voltammetry and DNA-binding properties of the bis(pyridine)bis(sparfloxacinato)nickel(II) complex

The neutral mononuclear nickel(II) complex with the quinolone third-generation antibacterial drug sparfloxacin in the presence of the nitrogen-donor heterocyclic ligand pyridine has been synthesized and characterized. Sparfloxacin is deprotonated acting as a bidentate ligand coordinated to the Ni(II) ion through the ketone oxygen and a carboxylato oxygen. The crystal structure of bis(sparfloxacinato)bis(pyridine)nickel(II), 1, has been determined with X-ray crystallography. The cyclic voltammograms of the complex have been recorded in dmso solution and in 1/2 dmso/buffer (containing 150 mM NaCl and 15 mM trisodium citrate at pH 7.0) solution and the corresponding redox potentials have been estimated. The biological activity of the complex has been evaluated by examining its ability to bind to calf-thymus DNA (CT DNA) with UV and fluorescence spectroscopies and cyclic voltammetry. UV study of the DNA-interaction of the complex has shown that it can bind to CT DNA and the DNA-binding constant has also been calculated. The cyclic voltammograms of the complex in the presence of CT DNA have shown that the complex can bind to CT DNA by the intercalative mode. Competitive study with ethidium bromide (EB) has shown that the complex can displace the DNA-bound EB indicating that the complex binds to DNA in strong competition with EB for the intercalative binding site.     

Quantitative study of the quasiequilibrium in the system (hydroxo)oxo-(5,10,15,20-tetraphenylporphynato)-molybdenum(V)-piperidine in toluene medium

The quasiequilibrium interaction of (hydroxo)oxo-(5,10,15,20-tetraphenylporphynato)molybdenum(V) and piperidine in the toluene medium has been studied by means of chemical kinetics and spectrophotometric titration. It has been revealed that the molecular complex formation proceeds as slow irreversible salt formation reaction. It is preceded by the stages of equilibrium substitution of the hydroxo group OH-with piperidine, the outer sphere cationic complex formation [K ₁ (2.03±0.28)×10³ M^?1]; and by the coordination of the second piperidine molecule to the cationic complex (K ₂ 1.76±0.39 M^?1). The complex formation has been completely kinetically described: the rate equations and rate constants have been derived, and the rate limiting stage has been identified. In addition, the physicochemical data on the intermediates and products are presented. The prospects of application of the mixed porphyrin-containing complex as piperidine receptor, alkaloids and pharmaceuticals building block, have been justified.     

Interaction of Poly(benzoyl thiocarbamate)-Modified Hyperbranched Polyester with Co(II) and Cu(II) Nitrates

The interaction of Co(NO3)2 and Cu(NO3)2 with hyperbranched polyester containing 7 terminal benzoyl thiocarbamate groups has been studied by IR-Fourier and electron absorption spectroscopy. А new polynuclear complexes of Co(II) and Cu(II) with poly(benzoyl thiocarbamate)-modified hyperbranched polyester have been synthesized. It has been found that the oxygen and sulfur atoms of the peripheral benzoyl thiocarbamate fragments of the macroligand are involved in coordination with metal ions, the metal to ligand ratio being 7 : 1.     

Mannich aminomethylation reactions of a series of bis(α-amino acidato)metal(II) complexes with formaldehyde and diethylmalonate: Crystal structure of (5,5-dicarboxyethyl-3,7-diazanonanedioato)copper(II) monohydrate

Mannich aminomethylation reactions involving M(aa)₂, where M = Cu, Ni and aa = glycine(gly), dl-alanine(dl-ala), l-alanine(l-ala), with formaldehyde and diethylmalonate have been carried out, resulting in carboxylate appended systems in high yield. All the compounds have been characterized by UV-Vis spectroscopy, infrared spectroscopy and elemental analysis. One of the synthesized complexes, (5,5-dicarboxyethyl-3,7-diazanonanedioato)copper(II) monohydrate, has been characterized by single crystal XRD and has been used as catalyst in the hydrogen peroxide-induced degradation of pyrocatechol violet (PCV) dye. The variations in the rate of degradation of the dye with respect to change in concentration of hydrogen peroxide, dye, catalyst and pH have been studied. Effect of addition of NaCl has been studied and a suitable mechanism based on the formation of free radical species during the degradation process has been proposed.     

Polyfluorocyloalkenes Part XI Perfluoro - bicyclo(3,3,0) oct-7(8)-ene, - bicyclo(4,3,0)-non-8(9)-ene and - bicyclo (4,4,0)-dec-9(10)-ene and some derivatives

Tetradecafluorobicyclo (4,3,0) non-8(9)-ene has been prepared by cobaltic fluoride fluorination of decafluoro indane. The reactivities of the double bonds in dodecafluorobicyclo (3,3,0) oct-7(8)-ene and hexadecafluorobicyclo (4,4,0) dec-9(10)-ene have been studied qualitatively by the use of chlorine, methanol, cobaltic fluoride, ammonia and dimethylamine and the derivatives so obtained have been characterised.     

3He NMR study of (3)He@C(60)H(6) and (3)He@C(70)H(2)(-)(10)

The (3)He NMR of (3)He@C(60)H(6), (3)He@C(70)H(2), (3)He@C(70)H(4), (3)He@C(70)H(8), and (3)He@C(70)H(10) have been investigated. A new, unidentified C(60)H(6) isomer has been found by using (3)He NMR. (3)He@C(70)H(10) shows the most downfield-shifted (3)He NMR resonance among the neutral C(70) derivatives.     

Functionalized 3,4-ethylenedithiathiophenes (EDTTs) as building blocks for poly (3,4-ethylenedithiathiophene) (PEDTT) derivatives

A convenient and straightforward procedure has been developed for the preparation of functionalized 3,4-ethylenedithiathiophene (EDTT) derivatives by using a new bromomethyl-EDTT derivative as a versatile synthon. Based on this procedure a novel EDTT derivative endowed with 9,10-anthraquinone moieties has been synthesized and electrochemically polymerized to yield a donor-acceptor PEDTT derivative.     

Diverse evolution of [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 2, 3) metalloligands in CH(2)Cl(2)

The nucleophilicity of the [Pt(2)S(2)] core in [[Ph(2)P(CH(2))(n)PPh(2)]Pt(mu-S)(2)Pt[Ph(2)P(CH(2))(n)PPh(2)]] (n = 3, dppp (1); n = 2, dppe (2)) metalloligands toward the CH(2)Cl(2) solvent has been thoroughly studied. Complex 1, which has been obtained and characterized by X-ray diffraction, is structurally related to 2 and consists of dinuclear molecules with a hinged [Pt(2)S(2)] central ring. The reaction of 1 and 2 with CH(2)Cl(2) has been followed by means of (31)P, (1)H, and (13)C NMR, electrospray ionization mass spectrometry, and X-ray data. Although both reactions proceed at different rates, the first steps are common and lead to a mixture of the corresponding mononuclear complexes [Pt[Ph(2)P(CH(2))(n)PPh(2)](S(2)CH(2))], n = 3 (7), 2 (8), and [Pt[Ph(2)P(CH(2))(n)PPh(2)]Cl(2)], n = 3 (9), 2 (10). Theoretical calculations give support to the proposed pathway for the disintegration process of the [Pt(2)S(2)] ring. Only in the case of 1, the reaction proceeds further yielding [Pt(2)(dppp)(2)[mu-(SCH(2)SCH(2)S)-S,S']]Cl(2) (11). To confirm the sequence of the reactions leading from 1 and 2 to the final products 9 and 11 or 8 and 10, respectively, complexes 7, 8, and 11 have been synthesized and structurally characterized. Additional experiments have allowed elucidation of the reaction mechanism involved from 7 to 11, and thus, the origin of the CH(2) groups that participate in the expansion of the (SCH(2)S)(2-) ligand in 7 to afford the bridging (SCH(2)SCH(2)S)(2-) ligand in 11 has been established. The X-ray structure of 11 is totally unprecedented and consists of a hinged [(dppp)Pt(mu-S)(2)Pt(dppp)] core capped by a CH(2)SCH(2) fragment.     

Kinetics and mechanism of NO production in the Ru(III)-(edta) mediated oxidation of L-arginine with H(2)O(2)

The kinetics of the Ru(III)-(edta) (edta(4-) = ethylenediaminetetraacetate) catalyzed oxidation of l-arginine by H(2)O(2) mimicking the action of nitric oxide synthases (NOSs) has been studied spectrophotometrically. The time course of the reaction of [Ru(V)(edta)O](-) with l-arginine was followed at 390 nm under catalytic turn-over conditions. Formation of NO in the reacting system has been confirmed with an isolated nitric oxide free radical analyzer. A detailed reaction mechanism in agreement with the spectral and kinetic data is presented.     

Solid-state NMR study of the anionic conductor Ca-doped Y(2)Ti(2)O(7)

Doping the pyrochlore (Y(2)Ti(2)O(7)) with the Ca(2+) has been reported to improve the oxygen ionic conductivity. (17)O and (89)Y solid-state NMR has been used in work reported here to probe the local environment of the oxygen and yttrium sites in these materials. Although the conductivity of these materials is only moderate, variable-temperature, one-dimensional (17)O NMR experiments and two-dimensional (17)O magnetization exchange spectroscopy show that oxygen-ion jumps occur between the oxygen sites nearby titanium. Motion at ambient temperatures involves the O1 and local environments created by the Ca(2+) doping; motion does not involve the O2 oxygen site coordinated to four yttrium ions.     

The X-ray revision of the structure of bis(4-hydroxybenzhydrazide)copper(II) sulfate(VI) dihydrate and its vibrational spectroscopy

The structure of known copper(II) complex with 4-hydroxybenzoic acid hydrazide has been corrected on the basis of a new X-ray analysis. It has been found, that the sulfate(VI) ion is bonded in apical position of Cu(II) coordination pyramid having two organic ligands at the base. Two water molecules are not coordinated as has been postulated before, but stabilizes the sulfate(VI) group orientation and link the layers of complex molecules by strong hydrogen bonds. The detailed interpretation of the measured IR and Raman spectra has been performed with aid of both: quantum calculations as well as H/D and ⁶³Cu–⁶⁵Cu isotope substitution.