Preparation of Tc-HA complex by displacement of thiourea from the hexakis(thiourea-S)technetium(III) complex

The complexation of technetium with humic acid is usually done by a reduction of pertechnetate by Sn²⁺ ions. A Tc-HA complex can be scavenged in a Sn-HA complex, if tin is present as reductant. The main aim of the study was a preparation of the Tc-HA complex without impurities of Sn ions or other metal reductant, which was performed by a ligand exchange with hexakis(thiourea-S)technetium(III) under nitrogen atmosphere at pH 5.5. The [Tc(tu)₆]³⁺ complex was prepared from TcO₄ ^- in acidic solution with thiourea as a reductant. Presence of the Tc-HA complex and other technetium species was determined by gel chromatography, paper chromatography and dialysis. Yield of Tc-HA complex was about 80% and reaction mixture contains about 20% of technetium dioxide, which is a side product of ligand-exchange.     

Thiolato-technetium complexes. 4(1): Synthesis,characterization and electrochemical properties of bis(1,2-bis(dimethylphosphino)-ethane)technetium(III) complexes with arene-thiolato ligands

Summary The reaction of trans-[Tc^v(OH)(O)(DMPE)₂]²⁺ (DMPE = 1,2-bis(dimethylphosphino)ethane) with a series of arenethiols in base produces the novel complexes cis-[Tc^III-(SC₆H₄X-p)₂ (DMPE)₂]⁺ for X = H, Cl, Me, OMe, t-Bu. One of the complexes has been characterized by X-ray crystallography: cis-[Tc(SPh)₂(DMPE)₂]PF₆, chemical formula Tc₁S₂P₅F₆C₂₄H₄₂, crystallizes in the orthorhombic space group P2₁nb with Z = 4 and lattice parameters a = 9.311(1) Å, b=11.190(2) Å, c = 31.936(4) Å, Vol = 3327.3(8) ų. The final weighted R-value was 0.033. Averaged structural parameters are Tc—S = 2.29(2) Å, Tc—P (trans to P) = 2.42(1) Å, Tc—P (trans to S) = 2.49(3) Å, Tc—S—C = 118.5(5)°. The complexes have been characterized by FAB mass spectrometry and u.v.-vis. spectroscopy. The visible region charge transfer bands are diagnostic for cis geometry in the [Tc(SR)₂(DMPE)₂]⁺ complexes. Electrochemical and spectroelectrochemical measurements show reversible Tc^III/II redox couples in the range -0.19V to -0.38V versus Ag/AgCl (3 M NaCl). Irreversible couples are exhibited at ca. -1.1 V to -1.2 V for Tc^II/I and +0.7V to +0.9V for Tc^IV/III. Variation in redox potential is discussed in terms of sulphur nucleophilicity.On leave from the Department of Chemistry, The University of Tsukuba, Tsukuba, Ibaraki 305, Japan.On leave from Dipartimento di Chimica dell'Universita' di Sassari, Via Vienna, 2-Sassari, Italy.     

Infrared and laser Raman studies of [Ni(II)(dppe)Cl2] and [Co(III)(dppe)2Cl2]PF6 (dppe = 1,2-bis(diphenylphosphino)ethane)

Infrared and laser Raman spectral investigations of [Ni(II)(dppe)Cl2] and [Co(III)(dppe)2Cl2]PF6 have been made to determine the conformation and nature of bonding in Ni(II) and Co(III) dppe complexes. The stereochemistry of the two forms of these complexes has been confirmed. The role of steric interferences in cis-Planar [Ni(II)(dppe)Cl2] complex is interpreted in terms of reduction in symmetry upon coordination. The strong trans influence of the chelating dppe ligand is observed in the [Co(III)(dppe)2Cl2]PF6 complex. Both complexes exhibit the effect of crystalline field on molecular vibrations. The Fermi resonance overtone is also observed in these complexes.     

Investigation of the complex formation of technetium with thiourea by spectrophotometry and electromigration

TcO ₄ ^– is reduced by thiourea /tu/ to Tc/III/ in 6N HCl. By capillar electrophoresis three different cations have been identified with electrophoretic mobilities of u=/4.3–4.8/x10^–4 u=/3.2–3.8/x10^–4, and u=/2.2–2.8/x10^–4 cm² v^–1s^–1. These species were assigned to complex cations [Tc/tu/₆]³⁺, [Tc/tu/₅Cl]²⁺, and [Tc/tu/₄Cl₂]⁺, respectively. [Tc/tu/₆]³⁺ was identified by spectrophotometry according to recently published data. [Tc/tu/₅Cl]²⁺ was isolated and chemically characterized. The formation of the monovalent cation [Tc/tu/₅Cl₂]⁺ was concluded from spectrophotometrical measurements.     

Kinetics and mechanism of the oxidation of thiourea by chlorine dioxide

The stoichiometry and kinetics of the oxidation of thiourea (SC(NH₂)₂) by chlorine dioxide (ClO₂) have been studied by uv-vis spectrophotometry using conventional and stopped-flow mixing techniques at 25.0 ± 0.1°C, pH 0.3–4.8. In high acid and initial 10:1 molar ratio of thiourea to chlorine dioxide, thiourea is oxidized relatively rapidly to dithiobisformamidine ion ((NH₂)₂CSSC(NH₂)₂²⁺), which slowly decomposes to thiourea, sulfur, and cyanamide (NCNH₂). In high acid and excess ClO₂, thiourea is oxidized to relatively stable formamidine sulfinic acid ((NH) (NH₂)CSO₂H). In high acid and molar ratios of ClO₂ to thiourea of 5:1 and higher, some oxidation to formamidine sulfonic acid ((NH) (NH₂)CSO₃H) occurs. At lower acidity, along with Cl^?, the major ClO₂ reduction product, byproduct sulfate is detected and, at pH < 3, ClO₂^?, also, appears. Kinetics data were collected for high excess thiourea with varying pH. The [ClO₂]-time curves are straight lines with negative slopes that increase in magnitude with increasing [thiourea]. The dependence on [thiourea] is first-order; the dependence on [ClO₂] is zero-order for 90% of reaction. With decreasing pH, the rate increases and the disappearance of ClO₂ becomes autocatalytic. Studies of the effects of reaction products on the rate of reaction lead to the conclusion that autocatalysis at low pH is due to the greater reactivity of HClO₂ compared with ClO₂^?. A 10-step mechanism incorporating a slow one-electron transfer from thiourea to ClO₂ to generate the (NH) (NH₂)CS · radical and subsequent more rapid reactions has been constructed and implemented in a computer simulation which provides a reasonably accurate fit to the observed kinetics curves. © 1993 John Wiley & Sons, Inc.     

Polymerization of styrene and methyl methacrylate using a catalytic system based on 1,2–bis(diphenylphosphino)ethanenickel dibromide

Specific features of homo- and copolymerization of styrene and methyl methacrylate in the presence of the catalytic system NiBr₂dppe/PhI/Zn were studied.     

The radiolysis of bis/1,2-dicarbollyl/cobalt/III/ acid in H2O−CCl4 two-phase system

The radiation-induced oxidation of bis/1,2-dicarbollyl/cobalt/III/ acid to 8-monohydroxy-, and 8,8-dihydroxy-derivatives was observed in two-phase system of 4 to 96 vol. % of CCl₄ and H₂O. Carbon tetrachloride increases the radiation yields of the oxidation of the acid in the investigated dose region, nature of the radiolytic products being the same. The partial radiation yields in the system were ascertained.     

The recoil reaction of technetium in mer- and fac-tris/benzoylacetonato/ruthenium/III/

The recoil reactions of technetium produced by¹⁰⁰Ru/γ, p/^99mTc reaction were studied in γ-irradiated mer- and fac-Ru/ba/₃ targets. Yields of mer- and fac-Tc/ba/₃ were determined by column chromatographic separation developed in our previous work. In the initial recoil reaction yields mer-form of Tc/ba/₃ was much more abundant than fac-form in the mer-Ru/ba/₃, but the reverse held good in the fac-Ru/ba/₃ showing selectivity in recoil replacement reactions in geometrical isomers. In the annealing reactions, however, such selectivity disappeared and the fac/mer ratio for the annealed portions could be explained by the following mixed mechanisms of ligand incorporation. $$\begin{gathered} Tc/ba/_2^ + + ba^ - \to Tc/ba/_3 \hfill \\ Tc/ba/^{2 + } orTc^{3 + } + xba \to Tc/ba/_3 \hfill \\ /x = 2or3/. \hfill \\ \end{gathered} $$      

Three 18-Electron Tantalum(I) Compounds, TaCl(CO)(2)(dppe)(2), [TaCl(CO)(2)(dppe)(2)](2x), and TaCl(CO)(4)(dppe) (dppe = 1,2-Bis(diphenylphosphino)ethane), Which Exhibit Low Levels of Paramagnetism

Reductive carbonylation of TaCl(5) in the presence of 1,2-bis(diphenylphosphino)ethane (dppe) under the appropriate conditions results in the formation of TaCl(CO)(2)(dppe)(2) (1), as the major product, and the possibly cyclic oligomer [TaCl(CO)(2)(dppe)(2)](2)(x)() (2, 2x >/= 4) as a minor product. Carbonylation of 1 (1 atm) results in the rapid but reversible formation of TaCl(CO)(4)(dppe) (3). Solutions of all three compounds exhibit low levels of paramagnetism, possibly attributable to thermal population of low-lying triplet excited states. Crystal data for the toluene solvate of 1, C(68)H(64)ClO(2)P(4)Ta: triclinic, P&onemacr; (No. 2), a = 13.937(12) ?, b = 14.811(7) ?, c = 14.929(9) ?, alpha = 102.30(5) degrees, beta = 95.60(7) degrees, gamma = 98.41(5) degrees, Z = 2.     

Syntheses and crystal structures of organoindium(III) 1-D coordination polymers with bis(diphenylphosphino)alkane dioxides

Abstract

Bromomethyl-dibromo-indium(III), Br₂InCH₂Br, obtained from indium monobromide and methylene dibromide, reacts with hard and soft donor ligands to afford the corresponding indium(III) organometallic complexes. In this work, we investigated the conditions to prepare adducts of Br₂InCH₂Br using bis(diphenylphosphino)alkane dioxides acting as hard ligands. We report here the synthesis and crystal structures of two 1-D coordination polymers with the hard donor ligands Ph₂P(O)(CH₂)_mP(O)Ph₂ (m = 2, dppeO₂ and m = 6, dpphO₂). Compounds 1 and 2 with formulas [Br₂In(CH₂Br)(dppeO₂)]_n (1) and [Br₂In(CH₂Br)(dpphO₂)]_n (2) were characterized by IR and Raman spectroscopy and elemental analysis. We also obtained an ionic indium(III) compound with dppeO₂ acting as a chelating ligand with formula [InBr₂(dppeO₂)₂][InBr₃(CH₂Br)] (3). The crystal structures were determined for 1–3 using single crystal X-ray diffractometry. The geometry around the In(III) can be described as a trigonal bipyramid in 1 and 2, and the chains were packed onto the plane giving layers that are stabilized mainly by intermolecular interactions. Compound 3 has a square bipyramidal In(III) cation with formula [Br₂L₂In]⁺ and tetrahedral organoindium(III) anion with formula [Br₃InCH₂Br]^–. Hirshfeld surface analysis employing 2-D fingerprint plots have been used to analyze intramolecular and intermolecular interactions present in the solid state of the structures.     

Studies on the analytical chemistry of iodonium compounds. Part III

Summary A procedure is described for the determination of the diphenyliodonium cation in the range 1.0 to 4.0 mg, by extraction from solution buffered at p_H 9.5 into chloroform as the diethyldithiocarbamate followed by conversion into the copper(II) complex. Absorbance measurements are made on the chloroform solution of the copper(II) diethyldithio-carbamate at 435 nm, and a linear relation exists between absorbance and cation content within the range specified. The optimum conditions for the extraction are discussed.

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Zusammenfassung Ein Verfahren zur Bestimmung von Diphenyliodoniumkationen in der Größenordnung von 1,0 bis 4,0 mg wurde beschrieben. Es beruht auf deren Extraktion aus gepufferter Lösung (p_H=9,5) mit Chloroform als Diäthyldithiocarbamat und dessen Überführung in einen Kupfer(II)-komplex. Die Absorption des Kupfer(II)-diäthyldithiocarbamats in Chloroformlösung wurde bei 435 nm gemessen. Sie steht in linearem Verhältnis zur Kationenkonzentration. Die optimalen Bedingungen für die Extraktion werden erörtert.

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Résumé On décrit un procédé pour le dosage du cation diphényliodonium dans le domaine de 1,0 à 4,0 mg, en l'extrayant d'une solution tamponnée à p_H 9,5 par le chloroforme, à l'état de diethyldithiocarbamate puis en le transformant en complexe du cuivre-II. On effectue les mesures de densité optique sur la solution dans le chloroforme du diéthyldithiocarbamate de cuivre-II à 435 nm; il existe une relation linéaire entre la densité optique et la teneur en cation dans le domaine spécifié. On discute les conditions optimales pour effectuer l'extraction.

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Part II. Mikrochim. Acta [Wien]1966, 539.     

The use of bis(diphenylphosphino)amines with N-aryl functionalities in selective ethylene tri- and tetramerisation

A systematic study was conducted on the Cr catalysed tri- and tetramerisation of ethylene using bis(diphenylphosphino)amine ligands with N-aryl functionality. This study revealed that the oligomerisation reaction product selectivity is primarily dependent on the structure and size of the N-aryl groups.

Addition of sufficient steric bulk to the N-phenyl group via ortho-alkyl substitution increased the combined 1-hexene and 1-octene selectivity (overall alpha selectivity) to above 82% at an overall 1-octene selectivity of 56%. The introduction of a single carbon spacer between the N-atom and the aryl-moiety, as well as the addition of branching on this carbon, resulted in further selectivity improvements, achieving an overall 1-octene selectivity of 64% and an overall alpha selectivity of 84%. This was obtained at catalyst productivities in excess of 1,000,000 g/g Cr/h.     

Microdetermination of chlorine and bromine in some organic compounds by ion-selective electrodes

Summary The solid state ion-selective chloride and bromide electrodes are used for the microdetermination of chlorine and bromine in organic compounds. After combustion in an oxygen-filled flask, potentiometric titration with silver nitrate at pH 5–7 in presence of 50% dioxan is carried out. Results accurate to ±0.3% absolute are obtained with some partially and highly halogenated compounds.

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Mikrobestimmung von Chlor und Brom in einigen organischen Verbindungen mit Hilfe von ionenselektiven Elektroden

Zusammenfassung Chlorid- und bromidselektive Festkörperelektroden wurden zur Chlor- und Brombestimmung in teilweise bzw. hochhalogenierten organischen Verbindungen benutzt. Nach Verbrennung im Sauerstoffkolben erfolgt eine potentiometrische Titration mit Silbernitrat bei pH 5–7 in Gegenwart von 50% Dioxan. Die erhaltenen Ergebnisse sind auf ±0,3 % genau.

     

Coordination and reactivity of white phosphorus and tetraphosphorus trisulphide in the presence of the fragment CpFe(dppe) [dppe = 1,2-bis(diphenylphosphino)ethane]

The reaction of [CpFe(dppe)Cl] (1) [dppe = 1,2-bis(diphenylphosphino)ethane] with one equivalent of P₄ or P₄S₃ in the presence of a chloride scavenger, TlPF₆ or AgOTf (OTf = triflate, OSO₂CF₃), affords the complexes [CpFe(dppe)(η¹-P₄)]PF₆ (2) and [CpFe(dppe)(η¹-P_basal-P₄S₃)]OTf (3) which contain the tetrahedral P₄ and the mixed P₄S₃ cage molecule η¹-bound to the metal. Both P₄ and P₄S₃ yield furthermore the dimetal compounds [{CpFe(dppe)}₂(μ,η^1:1-P₄)](PF₆)₂ (4) and [{CpFe(dppe)}₂(μ,η^1:1-P_apical-P_basal-P₄S₃)](OTf)₂ (5), which contain the tetrahedral P₄ or the mixed-cage P₄S₃ molecule tethering two ruthenium fragments via two phosphorus atoms. All the compounds have been characterized by elemental analyses and NMR measurements. The crystal structure of 4 has been determined by X-ray diffraction methods. The complexes readily react with excess water under mild reaction conditions and the outcoming products have been identified.     

Development of a rapid and sensitive liquid chromatography/tandem mass spectrometry method for the determination of 1,2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel anti-cancer agent in rat plasma

A rapid and sensitive liquid chromatography/electrospray ionization tandem mass spectrometric (LC/ESI-MS/MS) method has been developed to determine 1, 2-[bis(1,2-benzisoselenazolone-3(2H)-ketone)]-ethane (BBSKE), a novel antineoplastic agent, in rat plasma. The analytes were separated on a C18 column with a mobile phase of methanol-water (75:25, v/v) and detected using a triple-quadrupole mass spectrometer in positive mode with the selective reaction monitoring. The characteristic ion dissociation transitions were m/z 603.0 --> 448.9 for derivatized BBSKE and m/z 631.0 --> 476.8 for derivatized internal standard. The assay was linear over a range of 1-1000 ng/mL with a lower limit of quantification of 1 ng/mL. Intra- and inter-day precisions were less than 9.6 and 5.0%, respectively, and the accuracy ranged from -5.2 to 4.0%. The validated method was successfully applied to the characterization of pharmacokinetic profile of BBSKE after oral administration in rats. Cop     

Aqueous polymerization on clay surfaces. III. The polymerization of methyl methacrylate by montmorillonite/thiourea initiating system

Initiation of polymerization of methyl methacrylate with redox system montmorillonite (with lattice Fe³⁺)–thiourea has been achieved. The rates are dependent on both clay mineral and thiourea. Amidosulfenyl radicals are believed to initiate the polymerization on the clay surface. The polymerization produced nonextractable clay–polymer adduct up to an extent of 70 wt %. The pH of the medium (in the acidic range) did not affect the polymerization rate.