Bimetallic palladium(II) and iron(III), titanium(IV), vanadium(V), cobalt(II), and copper(II) complexes with the [As2W19O67(H2O)]14− heteropolyanion

The formation of bimetallic Pd(II) and M = Fe(III), Ti(IV), V(V), Co(II), or Cu(II) complexes with the two-vacancy [As₂W₁₉O₆₇(H₂O)]^14? heteropolyanion (HPA) (below referred to as As₂W₁₉) has been studied by UV/Vis and IR spectroscopy and differential dissolution. In an aqueous solution at pH 6 and a Pd: M: As₂W₁₉ molar ratio of 1: 1: 1, heteropoly complexes (HPC) incorporating two different metals one being Pd(II) are formed. The resulting complexes were precipitated from solution as cesium salts. In the case of Pd(II) and M = Fe(III), Co(II), or Cu(II) ions, the precipitate contained bimetallic HPC [As₂W₁₉FePDO₆₇(H₂O)₂]^9? (65.9 wt %), [As₂W₁₉CoPdO₆₇(H₂O)₂]^10? (45.6 wt %), and [As₂W₁₉CuPdO₆₇(H₂O)₂]^10? (50.7 wt %) mixed with monometallic HPC [As₂W₁₉M₂O₆₇(H₂O)₂]^{(14 ? 2m)?} (As₂W₁₉M₂). In the case of Pd(II) and Ti(IV) or V(V), bimetallic HPC of a different composition were precipitated, namely, [As₂W₁₉Ti₂O₆₇(OH _x )₂ PdO]^{(10 ? 2x)?} (76.8 wt %) and [As₂W₁₉V₂O₆₇(OH _x )₂ PdO]^{(8 ? 2x)?} (15.0 wt %), where palladium ions are not incorporated in the HPC structure but are attached to the HPC surface, possibly, as hydroxide species. Using M = Pd(II), Ti(IV), V(V) ions and the HPA As₂W₁₉ ([M]: [As₂W₁₉] = 2 : 1, pH 6), new monometallic HPC, [As₂W₁₉Pd₂O₆₇(H₂O)₂]^10?, [As₂W₁₉Ti₂O₆₇(OH _x )₂]^{(10 ? 2x)?}, and [As₂W₁₉V₂O₆₇(OH _x )₂]^{(8 ? 2x)?} (x = 0, 1, or 2), were obtained.     

Bis(2,4–pentanedionato)vanadium(IV) aryloxides

Complexes of composition [VCl(acac)2(OAr1–4)] and [V(acac)2(OAr1–4)2] (HOAr1=HOC6H4NO2–4, HOAr2= HOC6H4OMe-4, HOAr3=HOC6H4But-4 and HOAr4= HOC6H2But-2,6–Me-4; acac=2,4–pentanedionato ion) have been synthesized by the reaction of [VCl2(acac)2] with the respective phenols or their trimethylsilyl derivatives. The complexes have been characterized by physicochemical and spectroscopic techniques. They are non-electrolytes in nitrobenzene. Room temperature magnetic moments in the 1.71–1.82B range are consistent with the VIV system. The reactions of [VCl(acac)2(OAr2)] and [VCl(acac)2(OAr3)] with chloride acceptors have been studied by conductance techniques and the formation of ionic complexes of the types [V(acac)2(OAr2,3)][MCl4] (M=Fe, Al or Sb) and [V(acac)2(OAr2,3)][MCl6] (M=P or Sb) is indicated by the conductance composition curves. Several of these complexes have been isolated and characterized.     

Medium Controlled Stoichiometric Complexation of Penicillin G—Potassium Drug with Se(IV), Nb(V), Ta(V), and Te(IV) Chlorides: Physicochemical and Antitumor Activity of the Complexes

Four new 1: 1 ratio of Se⁺⁴, Nb⁺⁵, Ta⁺⁵, and Te⁺⁴ penicillinate complexes are synthesized in the reaction of penicillin potassium salt (Pin-G-K) with Se(IV), Nb(V), Ta(V), and Te(IV) chlorides. Structures of the synthesized complexes are characterized by elemental analysis, conductivity, magnetic susceptibility, IR, UV-Vis, ¹H and ¹³C NMR, and mass spectra, SEM, TEM, and XRD. Diamagnetic and electronic spectral studies allow to elucidate the geometry of penicillinate chelates around central metal ions. The monomeric structures of Pin-G complexes with six or eight coordinated metal ions are proposed. The metal ions are coordinated toward Pin-G as tridentate chelates via the amide and β-lactam carbonyl, and monodentate carboxylate groups. According to powder XRD the complexes have crystalline to poly crystalline nature. In vitro antimicrobial activity of Pin-G complexes is tested against four bacteria pathogens: G^? (Klebsiella and Escherichia coli) and G+ (Staphylococcus epidermidis and Staphylococcus aureus). Anti-tumor activity of the Pin-G complexes is assessed against human hepato cellular carcinoma (HepG-2) and human breast cancer (MCF-7) tumor cell lines.

     

Die Bestimmung von Uran(VI) neben Uran(IV), Eisen(II, III), Vanadium (III, IV, V), Molybd?n (IV, VI) und Kupfer (II)

Ohne Zusammenfassung     

Die vollst?ndige Trennung eines Gemisches aus Zirkonium(IV), Kupfer(II), Molybd?n(VI), Titanium(IV), Vanadium(IV) und Magnesium(II) durch Ionenaustauschchromatographie

Ohne Zusammenfassung     

Spektrophotometrische Bestimmungen von Gold(III), Eisen(III), Cer(IV) und Vanadium(V) mit Pikramins?ure

Zusammenfassung Pikraminsäure wird als Reagens für die spektrophotometrische Bestimmung von Gold(III), Eisen(III), Cer(IV) und Vanadium(V) vorgeschlagen.Die einfach durchzuführenden Methoden werden durch Fremdionen wenig gestört.     

Eine Methode zur papierchromatographischen Trennung und Identifizierung von L-Noradrenalin (I), L-Adrenalin (II), L-Corbasil (III), Adrenalon (IV), Isopropyladrenalin (V) und anderen Phenyl?thylamin-Derivaten

Ohne Zusammenfassung     

Die quantitative Bestimmung organischer Pers?ure (I), Diacylperoxyd (II), Alkylhydroperoxyd (III), Dialkylperoxyd (IV) und organischer S?ure (V) nebeneinander

Ohne Zusammenfassung     

全钒液流电池高浓度下V(IV)/V(V)的电极过程研究

采用循环伏安、低速线性扫描和阻抗技术, 以石墨为电极, 研究了V(IV)/V(V)在较高浓度下的电极过程. 结果表明, 采用2.0 mol•L-1 的V(IV)溶液时, H2SO4浓度低于2 mol•L-1, V(IV)/V(V)反应极化大, 可逆性差, 表现为电化学和扩散混合控制; H2SO4浓度增至2 mol•L-1以上, V(IV)/V(V)反应的可逆性提高, 转为扩散控制, 且增加H2SO4浓度有利于阻抗的降低; 但H2SO4浓度超过3 mol•L-1, 溶液的粘度和传质阻力大, 阻抗反而增大. 在3 mol•L-1的H2SO4中, 随着V(IV)浓度的增加, 体系的可逆性和动力学改善, 阻抗减小; 但V(IV)浓度超过2.0 mol•L-1, 较高的溶液粘度导致溶液的传质阻力迅速增加, V(IV)/ V(V)的电化学性能衰减, 阻抗增大. 因此, 综合考虑电极反应动力学和电池的能量密度两因素, V(IV)溶液的最佳浓度为1.5～2.0 mol•L-1, H2SO4浓度为3 mol•L-1.     

Simultaneous speciation of arsenic (As(III), MMA, DMA, and As(V)) and selenium (Se(IV), Se(VI), and SeCN−) in petroleum refinery aqueous streams

High-performance liquid chromatography (HPLC) coupled to an ICP-MS with an octapole reaction system (ORS) has been used to carry out quantitative speciation of selenium (Se) and arsenic (As) in the stream waters of a refining process. The argon dimers interfering with the ⁷⁸Se and ⁸⁰Se isotopes were suppressed by pressurizing the octapole chamber with 3.1 mL min⁻¹ H₂ and 0.5 mL min⁻¹ He. Four arsenic species arsenite—As(III), arsenate (As(V)), monomethylarsonic acid (MMA), and dimethylarsinic acid (DMA)—and three inorganic Se species—selenite Se(IV), selenate Se(VI), and selenocyanate (SeCN⁻)—were separated in a single run by ion chromatography (IC) using gradient elution with 100 mmol L⁻¹ NH₄NO₃, pH 8.5, adjusted by addition of NH₃, as eluent. Repeatabilities of peak position and of peak area evaluation were better than 1% and about 3%, respectively. Detection limits (as 3σ of the baseline noise) were 81, 56, and 75 ng L⁻¹ for Se(IV), Se(VI), and SeCN⁻, respectively, and 22, 19, 25, and 16 ng L⁻¹ for As(III), As(V), MMA, and DMA, respectively. Calibration curve R ² values ranged between 0.996 and 0.999 for the arsenic and selenium species. Column recovery for ion chromatography was calculated to be 97 ± 6% for combined arsenic species and 98 ± 3% for combined selenium species. Because certified reference materials for As and Se speciation studies are still not commercially available, in order to check accuracy and precision the method was applied to certified reference materials, BCR 714, BCR 1714, and BCR 715 and to two different refinery samples—inlet and outlet wastewater. The method was successfully used to study the quantitative speciation of selenium and arsenic in petroleum refinery wastewaters.     

Complexes of N-phenyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(III), iron(III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new ligand, N-phenyl-N -2-furanthiocarbohydrazide (HPhfth), and its complexes with VO^IV, Mn^III, Fe^III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, i.r., n.m.r., u.v.–vis., mass and FAB mass spectral data. The room temperature e.s.r. spectra of the VO^IV, Fe^III and Cu^II complexes yield <g> values characteristic of square pyramidal VO^IV, octahedral Fe^III and square planar Cu^II, respectively. The Ni^II and Cu^II complexes semiconduct, but the Zn^II complex is an insulator at room temperature. However, the conductivity increases as the temperature increases from 303–383 K, with a band gap of 0.21–1.01 eV. HPhfth and its soluble complexes have been screened against several bacteria and fungi.     

Copper(II), nickel(II), cobalt(II) and oxovanadium(IV) complexes of substituted β-hydroxyiminoanilides

Complexes of the general formula, ML₂ [M = Cu^II, Ni^II, Co^II and OV^IV; L = 1,2,3,5,6,7,8,8a-octahydro-3-hydroxyimino-N-(4-X-phenyl)-l-phenyl-5-(phenylmethylene)-2-naphthalenecarboxamide (X = H, Me, OMe, Cl)] have been prepared and characterized on the basis of elemental analysis, magnetic moments and i.r., e.p.r. and electronic spectra. These metal complexes contain the N₄ chromophore with the ligand coordinating through nitrogens of the azomethine and deprotonated anilide functions. C.v. measurements indicate that the copper(II) complexes are quasi-reversible in acetonitrile solution. Square planar and square pyramidal structures are assigned respectively to the copper(II) and oxovanadium(IV) complexes, whereas tetrahedral geometry is assigned to the nickel(II) and cobalt(II) complexes. Deprotonated anilide nitrogen is involved in coordination and the presence of an electron-donating group para to the anilide function decreases the ΔE values of the d–d transitions while the value is found to increase when electron-withdrawing groups are substituted. Line spacing in the e.p.r. spectra of the copper(II) and oxovanadium(IV) complexes increases when methyl group is para to the anilide group, and decreases when this group is replaced by methoxy or chloro. The ν(C–N) of the anilide group and the ν(C-N) of the azomethine function of the oxime metal complexes are metal-sensitive and the blue shift for the above stretching frequencies follows the order: copper(II) > oxovanadium(IV) > nickel(II) ≈ cobalt(II). This revised version was published online in June 2006 with corrections to the Cover Date.     

Extraction behavior of uranium(VI), plutonium(IV), zirconium(IV), ruthenium(III) and europium(III) with γ-pre-irradiated solutions of N,N′-methylbutyl substituted amides in n-dodecane

The extraction of plutonium(IV), uranium(VI), zirconium(IV), europium(III) and ruthenium(III) with -pre-irradiated n-dodecane solutions of methylbutyl substituted hexanamide (MBHA), octanamide (MBOA) and decanamide (MBDA) from 3.5M HNO₃ has been studied as a function of absorbed dose up to 184×10⁴ Gray. The distribution ratios (K_d) of uranium(VI) decreased gradually up to a dose of 50×10⁴ Gray and became almost constant thereafter, while ruthenium(III) and europium(III) were not extracted in the entire dose range studied. The K_d values of Pu(IV) decreased gradually up to 10×10⁴ Gray, for MBOA, and 30×10⁴ Gray for MBHA and MBDA and then increased up to a dose of 72×10⁴ Gray, indicating the synergistic effect of radiolytic products at higher doses. The extraction of zirconium(IV) was found to increase gradually up to 72×10⁴ Gray. However, the steep fall in K_d values of plutonium(IV), zirconium(IV) beyond a dose of 72×10⁴ Gray was atrributed to third phase formation. The radiolytic degradation of amides was monitored by quantitative IR spectroscopy and was found to follow the order MBOA>MBDA>MBHA at 184×10⁴ Gray having the amines and carboxylic acids as the main radiolytic products.     

Complexes of N-nicotinoyl-N′-2-furanthiocarbohydrazide with oxovanadium(IV), manganese(II), iron(II & III), cobalt(II), nickel(II), copper(II) and zinc(II)

A new potential tetradentate ligand, N-nicotinoyl-N-2-furanthiocarbohydrazide (H₂Nfth), and its complexes with VO^IV, Mn^II, Fe^II,III, Co^II, Ni^II, Cu^II and Zn^II have been prepared and characterized by elemental analyses, magnetic susceptibility measurements, u.v.–vis, i.r., n.m.r., ES⁺ and FAB mass spectral data. The room temperature e.s.r spectra of the VO^IV and Fe^III complexes yield g values, characteristic of octahedral complexes. The Mössbauer spectra of [Fe(HNfth)₂] and [Fe₂(Nfth)₃] at room temperature and at 78 K suggest the presence of high-spin iron(II) and iron(III), respectively. The complexes are electrically insulating at room temperature, however, their conductivities increase as the temperature increases from 333–383 K, with a band gap of 0.46–0.77 eV, indicating their semiconducting behaviour. H₂Nfth and its soluble complexes have been screened against several bacteria and fungi.     

Silylmethyl and silylamino groups as ligands in tin(II), tin(IV), lead(II) and lead(IV) compounds—a multinuclear magnetic resonance study

We have studied tin(II), tin(IV), lead(II) and lead(IV) compounds of the type M[CH(SiMe₃)₂]₂ (5), M[N(SiMe₃)₂]₂ (6), M[N(SiMe₃)SiMe₂^tBu]₂ (7), Me₃MCH₂SiMe₃ (1), Me₃MCH(SiMe₃)₂ (3), Me₃MNHSiMe₂^tBu (2), Me₃MN(SiMe₃)₂ (4), Me₂M[N(SiMe₃)₂]₂, (8) and (Me₃M)₂NSiMe₂^tBu (9) by ¹³C, ¹⁵N, ²⁹Si, ¹¹⁹Sn and ²⁰⁷Pb NMR spectroscopy. In some cases, two-dimensional (2-D) ¹³C/¹H and ²⁹Si/¹H heteroscalar-correlated NMR spectra served for the comparison of the signs of the respective coupling constants [ⁿJ(M ¹³C), ²J(M²⁹Si) and ⁿJ(M¹H)]. The ¹³C and ¹⁵N NMR parameter of comparable compounds (replacement of the CH or CH₂ fragment by a nitrogen atom or the NH group, respectively), show analogous trends. In the monomeric M(II) compounds (5, 6, 7) the peculiar electronic situation at the metal is reflected by the extreme deshielding of the metal nuclei (e.g. δ²⁰⁷ Pb for 5b = +9110 ppm), by the strongly deshielded ¹³C (5) and ¹⁵N nuclei (6, 7), as well as by large negative contributions to the reduced nuclear spin—spin coupling constants ¹K(M¹³C) (5) and ¹K(M¹⁵N) (6). In the M(II) compounds 5 the ¹¹⁹Sn and, in particular, the ²⁰⁷Pb longitudinal and transverse nuclear relaxation is dominated by the chemical-shift-anisotropy mechanism. This is also true for 6 and 7, in which the transverse relaxation rate is further increased by scalar relaxation of the second kind owing to partially relaxed scalar coupling ¹J(M¹⁴N).     

Synthesis,characterization and oxidase catalytic activity of vanadium(IV) and oxovanadium(IV) complexes with Schiff base ligands derived from β-diketones

New complexes of vanadium(IV) and oxovanadium(IV) with Schiff base ligands derived from -diketones and ethanolamine or o-aminophenol have been prepared and characterized by elemental analyses, electrical conductance, magnetic moment measurements, and by i.r., u.v.–vis. and e.p.r. spectroscopy. A distorted octahedral environment was proposed for the vanadium(IV) and oxovanadium(IV) complexes. The spectroscopic results were utilized to compute the important ligand field parameters. Three adduct complexes were isolated owing to the interaction of one oxovanadium complex with Lewis-bases in MeOH. Vanadium(IV) complexes exhibit promising catalytic activity towards the aerobic oxidation of p-phenylenediamine (PPD) to the corresponding semi-oxidized form (PPD⁺). A linear correlation exists between the oxidase catalytic activity and the Lewis acidity of the central vanadium(IV) ion created by the donating properties of the parent ligand.     

In search of the Bailar and Rây-Dutt twist mechanisms that racemize chiral trischelates: a computational study of Sc(III), Ti(IV), Co(III), Zn(II), Ga(III), and Ge(IV) complexes of a ligand analogue of acetylacetonate

Two nondissociative processes, a Bailar twist that proceeds through a transition state of D3h symmetry and a Ray-Dutt twist mechanism that proceeds through a transition state of C(2v) symmetry, as well as dissociative/associative processes are potential mechanisms by which the enantiomeric forms of chiral metal trischelates can be interconverted. We have applied density functional theory to locate the stationary points for metal trischelates of a beta-diketonate ligand analogue that interconvert Delta and Lambda forms via one or both of these nondissociative pathways. Although many two-dimensional static representations of the Bailar and Ray-Dutt twist mechanisms can be found in the chemical literature (of the type shown in Figure 1), in this communication, we present our results in the form of interactive three-dimensional animations as a means of enhancing the scientific perception of these fluxional processes.