Zur polarographischen Reduktion von Molybdän(VI) und Molybdän(V) in Gegenwart von Citronensäure

According to the ratio of citric acid to molybdenum different citratomolybdenum(VI) complexes exist at pH <2. Only one citratomolybdenum(VI) complex exists in solutions with a great excess of citric acid (20:1). In such solutions the polarographic reduction of Mo^VI proceeds in two waves: First Mo^VI → M^V, then Mo^V → Mo^IV, which disproportionates into Mo^V and Mo^III however. Furthermore, it is possible that the Mo^IV reacts with Mo^VI forming Mo^V, so that also a catalytic character can be attributed to the second wave besides a kinetic one.     

Synthese,spektroskopische Eigenschaften und elektrochemisches Verhalten von Ruthenium(II)-Komplexen mit zweizähnigen Stickstoffliganden

Synthesis, Spectroscopic Data and Electrochemical Behavior of Ruthenium(II) Complexes with Bidentate Ligands The syntheses of coordination compounds of ruthenium (II) with bidentate nitrogen donors (aa) is described. The ligands (aa) used are related to dipyridyl, but differ from the latter in size of the π-electron systems. In some ligands, e.g. 10 , the two halves of the molecule are forced to be non planar by the aliphatic bridge between the two rings accomodating the nitrogen ligand atoms. The syntheses of the complexes Ru(dipy)₂(aa)²⁺, Ru(dipy)(aa)²⁺₂ and Ru(aa)²⁺₃ ((aa) 1–17 ) are described. Generally the crystalline salts with PF ^?₆ as counter-ion have been obtained. The complexes are characterized by elementary analysis, electronic spectra, infrared spectra, cyclic voltammograms, proton nuclear magnetic resonance spectra and, for those which have been obtained in optically active forms also by circular dichroism. In the discussion special emphasis is given to the change of properties compared to the well investigated Ru(dipy)²⁺₃ complex. In the visible range of the spectrum all complexes show one or several spin allowed charge transfer transitions at longer wave lengths then Ru(dipy)²⁺₃. The ground state oxidation potential to the 3+ state are little affected by substitution of one or more of the dipy ligands in Ru(dipy)²⁺₃ by the ligands (aa), whereas the reduction behavior is strongly influenced by such substitutions. The ¹H-NMR. spectra indicate rigid conformations of some of the nonplanar (aa)-ligands in the complexes.     

Molybdän(VI)-fluorid-pentafluorotellurate(VI) und Molybdän(VI)-oxid-fluorid-pentafluorotellurate(VI): MoFn(OTeF5)6−n und MoOFn(OTeF5)4−n

Molybdenum(VI)fluoride-pentafluorotellurates(VI) and Molybdenum(VI)oxide-fluoridepentafluorotellurates(VI): MoF_n(OTeF₅)_6?n and MoOF_n(OTeF₅)_4?n In MoF₆ fluorine can be replaced by F₅TeO-groups by means of B(OTeF₅)₃. Rearrangement reactions and internal fluorination finally leads to MoF_n(OTeF₅)_6?n and MoOF_n(OTeF₅)_4?n.     

Flüssig-Flüssig-Extraktion von Vanadium mit ausgewählten zweizähnigen Chelatbildnern

Liquid-Liquid Extraction of Vanadium with Bidentate Ligands The extraction of vanadium(V) as well as vanadium(IV) with thenoyltrifluoracetone, 1-phenyl-3-methyl-4-benzoylpyrazol-5-one, N-benzoyl-N-phenylhydroxylamine, maltol, di-2-ethylhexylphosphoric acid, and selected 8-quinolinols was studied in comparison with corresponding thioanalogue compounds. In the reaction of vanadium(IV) with 7-methyl-8-quinolinol vanadium(IV) and vanadium(V) compounds were isolated side by side.     

Zinn(IV)-Komplexe mit dreizähnigen diaciden Liganden

Tin(IV) Complexes with Tridentate Diacidic Ligands By template reactions including bis(acetylacetonato)-dichloro-tin(IV) and O-aminophenol as well as o-aminothiophenol, benzoylhydrazine, and thiobenzoylhydrazine the tin chelates of tridentate diacidic ligands containing ligator atoms were prepared. To characterize the compound, IR, UV-VIS and Mössbauer spectroscopy were used. Crystal structure analyses demonstrate the existence of disturbed octahedral structures. Bis[acetylacetonbenzoylhydrazonato(2-)]tin(IV): space group P2₁/c, Z = 4, 2501 observed unique reflections, R = 0.045. Lattice dimensions at 20°C: a = 992.3, b = 2405.5, c = 1071.8pm, β = 116.94°. Bis[acetylacetonthiobenzoylhydrazonato(2-)] tin(IV): space group P2₁/c, Z = 4, 3603 observed unique reflections, R= 0.029. Lattice dimensions at 20°C: a = 1581.5, b = 947.8, c = 1644.9pm, β = 90.32°.     

Metall(0)-Komplexe von Nickel und Molybdän mit Benzil-bis-phenyliminen als Chelatliganden

Metal(0) Complexes of Nickel and Molybdenum with Benzil-bis-phenylimines as Chelateligands Benzil-bis-phenylimines form with Mo(CO)6 stable tetracarbonylcomplexes; their spectroscopical behaviour shows, that the ligands are π-electron acceptors. Substitution by R₃P gives tricarbonylcomplexes. Some nickel(0) complexes (NiL₂, Ni(R₃P)L) are described. The magnetical and spectrophotometrical properties of these chelatcomplexes are investigated.     

Die spezifische Extraktion von Uran(VI) mit N-Benzylanilin und N-Butylanilin

Zusammenfassung Zwei Methoden zur extraktiven Abtrennung des Urans von einer Reihe von Ionen werden beschrieben. Die Extraktion erfolgt aus schwefelsaurer Lösung mit N-Benzylanilin bzw. N-Butylanilin, gelöst in Chloroform. Nach Reextraktion mit Wasser erfolgt die quantitative Bestimmung mit PAR.

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Summary Two methods for the extractive separation of uranium from a number of ions are described. The extraction is from a solution containing sulfuric acid by means of N-benzylaniline or N-butylanilin, dissolved in chloroform. After reextraction with water, there follows the quantitative determination with PAR.

     

Neue Oxooxalatokomplexe des Molybdän(VI)

New Osooxalatocomplexes of Molybdenum (VI) The preparation of the compounds Cs₂[Mo₂O₅F₂(C₂O₄)] · H₂O and Cs₂[Mo₂O₄Cl₄(C₂O₄)] · 2 H₂O is reported. The structure of the complex anions, which are containing quadridentated oxalate ligands, is derived from their vibration spectra. The compounds [NR₄]₂[Mo₂O₄F₄(C₂O₄)] with R = CH₃ and C₂H₅ are examined for comparison.     

Extraktion von 3d-Metallionen mit zweizähligen Sulfonamiden. I. Liganden mit Schwefel bzw. heterocyclisch gebundenem Stickstoff als zweitem Haftatom

Extraction of 3d-Metal Ions by Bidendate Sulfonamides. I. Ligands with Sulfur or Heterocyclic Nitrogen as a Second Donor Atom The properties of 2-acetylpyridine-p-toluensulfonylhydrazone (APSH - H), arensulfonylthioureas (I), and the esters of arensulfonylmonothiocarbamic acid (II) or arensulfonyldithiocarbamic acid (III) as extractants for the late 3d-metal ions are proved. APSH-H is comparable to the proprietary extractant LIX 34. But, because of the special structure of the corresponding 1,2-chelates, the pH_1/2-values of nickel(II) and cobalt(II) are ≈2 units lower. The pK_s-values, measured in dioxane-water mixtures (75 per cent v/v), increase in the order III < II < I. In aqueous solutions compounds of type III are acids of medium strength. In the case of compounds of type I the substituents of the non-sulfonated nitrogen have a strong influence on the pK_s-values (ΔpK_s = 4.6). Among the late 3d-elements, the ligands II and III extract only copper(II) (pH_1/2 ～2.7 or ～1.6), the ligands I extract zinc(II), cobalt(II), and nickel(II) as well, but not iron(II) and iron(III). The reasons of this unique behaviour are discussed.     

Template-Reaktion von Bis(acetylacetonato)-dioxo-molybdän(VI) mit Benzoylhydrazin und Triphenylphosphan

Template Reactions of Bis(acetylacetonato)-dioxo-molybdenum(VI) with Benzoylhydrazine and Triphenylphosphane By reaction of MoO₂(acac)₂ with C₆H₅? CO? NH? NH₂ in the presence of P(C₆H₅)₃ Mo(NNCOC₆H₅)((CH₃)₂CNNCOC₆H₅)(P(C₆H₅)) was obtained besides MoO(acac-NNHCOC₆H₅)(NNHCOC₆H₅). The earlier compound was characterized by X-ray structural analysis. Crystallographic data see ?Inhaltsübersicht”?.     

Solvatochromie von Metall(0)-Komplexen der 6. Nebengruppe mit zweizähligen Azomethinen als Liganden

Solvatochromism of Subgroup VI Metal(0) Complexes with Bidentate Azomethine Ligands Some mononuclear and binuclear chelat compounds of azomethines, derived from the carbonyls of molybdenum and chromium are described. The spectrophotometrical behaviour of the compounds is compared with the behaviour of the diazabutadiene and dipyridyl metalcarbonyls. The complexes show strong negative solvatochromic effects in organic solutions and in polymers.     

Komplexbildung und photometrische Bestimmung von Wolfram(VI) mit Thioglykols?ure und verwandten Chelatbildnern

Zusammenfassung W(VI) bildet mit Thioglykolsäure und Glykolsäure mäßig stabile Fünfringchelate der Zusammensetzung WR₂, mit Glycin ein sehr schwaches WR. Chelate mit den Sechsringbildnern 3-Mercaptopropionsäure und o-Mercaptobenzoesäure sind nicht nachweisbar. Das Thioglykolsäurechelat kristallisiert aus Methanol als gelbes Na-Salz WO₂(SCH₂COONa)₂·2CH₃OH und ist mit Di-phenylguanidin als Ionenpaar in Butanol extrahierbar. Die photometrische Wolframbestimmung mit Thioglykolsäure in wäßriger Lösung erreicht eine Bestimmungsgrenze von = 0,92 ppm W (P=99,9%;M=2) und eine Standardabweichung vons=0,24 ppm W (f=21).

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Chelation and photometric determination of tungsten (VI) with thioglycolic acid and related compounds

Summary W(VI) forms moderately stable, five-membered ring chelates of the composition WR₂ with thioglycolic and glycolic acid, and a very weak WR with glycine. Chelation with the six-ring forming 3-mercaptopropionic acid and o-mercaptobenzoic acid could not be detected. The chelate with thioglycolic acid crystallizes from methanol as the yellow sodium salt WO₂(SCH₂COONa)₂·2CH₃OH and can be extracted into butanol as an ion pair with diphenylguanidine. The photometric determination of tungsten with thioglycolic acid has a determination limit of = 0.92 ppm W (P=99.9%;M=2) and a standard deviations=0.24 ppmW (f=21).

Wir danken Herrn Prof. F. Umland für die Förderung dieser Untersuchungen sowie H. Weber, M. Lamm und U. Görs für ihre Mithilfe.     

Dichlorphosphatokomplexe der Nitridchloride von Molybdän und Wolfram

Dichlorophosphate Complexes of the Nitrido Chlorides of Molybdenum and Tungsten Tetraphenylarsonium dichlorophosphate AsPh₄[PO₂Cl₂], is prepared by the reaction of AsPh₄Cl with P₂O₃Cl₄. The vibrational spectrum is reported as well as the valence force constants of the [PO₂Cl₂]^? ion. The f-values are clearly smaller than those of the isoelectronic SO₂Cl₂ molecule. The dichlorophosphate ion forms complexes with the nitride chlorides MNCl₃ (M ? Mo, W) of the type [MNCl₃(PO₂Cl₂)]₂^2?, which are characterized by their i.r. spectra.