Über Alkalihexafluorobismutate(V)

The compounds LiBiF₆ (a = 5.18, c = 13.9₉ Å), NaBiF₆ (a = 5.47, c = 15.1₆ Å), RbBiF₆ (a = 7.71, c = 7.89 Å) and CsBiF₆ (a = 7.93, c = 8.27 Å, hexagonal lattice constants) are rhombohedral. The hexagonal unit cell contains three formula weights. LiBiF₆ and NaBiF₆ are isotypic with LiSbF₆, RbBiF₆ and CsBiF₆ are KOsF₆-isotypes. All compounds are colourless and very moisture sensitive.     

Solid Solution Formation between Vanadium(V) and ­Tungs­ten(V) Oxide Phosphate

The solid solutions (V_1–xW_x)OPO₄ with β‐VOPO₄ structure type (0.0 ≤ x ≤ 0.01) and α_II‐VOPO₄ structure type (0.04 ≤ x ≤ 0.26) were obtained from mixtures of V^VOPO₄ and W^VOPO₄ by conventional solid state reactions and by solution combustion synthesis. Single crystals of up to 3 mm edge length were obtained by chemical vapor transport (CVT) (800 → 700 °C, Cl₂ as a transporting agent). Single crystal structure refinements of crystals at x = 0.10 [a = 6.0503(2) Å, c = 4.3618(4) Å, R₁ = 0.021, wR₂ = 0.058, 21 parameters, 344 independent reflections] and x = 0.26 [a = 6.0979(2) Å, c = 4.2995(1) Å, R₁ = 0.030, wR₂ = 0.081, 21 parameters, 346 independent reflections] confirm the α_II‐VOPO₄ structure type (P4/n, Z = 2) with mixed occupancy V/W for the metal site. Due to the specific redox behavior of W⁵⁺ and V⁵⁺, solid solutions (V_1–xW_x)OPO₄ should be formulated as (V^IV_xV^V_1–2xW^VI_x)OPO₄. The valence states of vanadium and tungsten are confirmed by XPS measurements. V⁴⁺ with d¹ configuration was identified by EPR spectroscopy and magnetic measurements. Electronic spectra of the solid solutions show the IVCT(V⁴⁺ → V⁵⁺) and the LMCT(O^2– → V⁵⁺). (V_0.74W_0.26)OPO₄ powders exhibit semi‐conducting behavior (E_g = 0.7 eV).     

μ-Oxalato Complexes du Molybdène(V) et (VI) et du Niobium(V)

Molybdenum(V) and (VI) and Niobium (V) μ-Oxalato Complexes The complexation of the « oxalato » ligand as bis-(bidentate) bridge in the solid compounds {(C₂H₅)₄N}₂ {M₂^VO₂X₆(C₂O₄)} or {(C₂H₅)₄N}₂ {M^VIO₄X₄(C₂O₄)} (with M^V = Mo or Nb; M^VI = Mo and X = F, Cl, Br) is characterized on the basis of their infrared spectra and analytical data. The behaviour, of the Mo^V dimer compounds in near corresponding mononuclear species at room temperature, because of the low interaction between metallic ions.     

Mixed halodicyclopentadienyl-niobium(V) and -tantalum(V)

Oxidation of (η⁵-C₅H₅)₂MCl (M = Nb, Ta) with 1 mol of Cl₂, Br₂ or I₂ gives (η⁵-C₅H₅)₂MClX₂ whereas the reaction with an excess of the halogen gives the cationic complexes [η⁵-C₅H₅)₂MClX]⁺ X₃^? (X = Br, I). Similar oxidation of (η⁵-C₅H₅)₂MCl₂ with 0.5 mol of halogen gives (η⁵-C₅H₅)₂MCl₂X complexes, but if the halogen is used in excess cationic [η⁵-C₅H₅)₂MCl₂]⁺ X₃^? (X = Br, I; M = Ta and X = I, M = Nb) are obtained. All these complexes can also be obtained simultaneously by oxidizing (η⁵-C₅H₅)₄M₂Cl₃, and the separation is fairly easy in most cases. Conductivity and IR and NMR data are discussed.     

Two square‐pyramidal chromium(V)–nitride complexes: bis­(2‐methyl­quinolin‐8‐olato)nitridochromium(V) and nitridobis(2‐sulfidopyridine N‐oxide)chromium(V)

Two new chromium(V)–nitride complexes with a coordination sphere completed by bidentate ligands have been synthesized and structurally characterized. Bis(2‐methyl­quinolin‐8‐olato)nitridochromium(V), [Cr(C₁₀H₈NO)₂(N)], has the coordination sphere completed by an equatorial N₂O₂ set of ligators. The compound crystallizes with the five‐coordinate complexes at sites with twofold rotational symmetry and all Cr—N bond directions aligned with the crystallographic b axis. Nitridobis(2‐sulfidopyridine N‐oxide)chromium(V), [Cr(C₅H₄NOS)₂(N)], crystallizes with the mol­ecules on general positions and has an equatorial S₂O₂ coordination environment, which is unprecedented among nitride complexes of the first‐row transition metals. In both systems, Cr[triple‐bond]N bonds are short at ca 1.56 Å.     

Untersuchungen über Bismut(V)-oxid

Studies on Bismuth(V) Oxide Higher bismuth oxides have been prepared by oxidation of Bi³⁺ and by hydrolysis of bismuthates ( V ) under variable conditions. The oxides were characterized by means of chemical and thermoanalytical methods as well as with X-rays. Beside BiO₂ the existence of 4 different forms (α β σ, δ) of BiO_2,5 was ascertained.     

The preparation of new oxoniobium(V) complexes from hydrated Niobium(V) Oxide: the crystal and molecular structure of Oxotris(2-pyridinolato-<Emphasis Type="Italic">N</Emphasis>-oxide)niobium(V)

Three oxoniobium(V) complexes ONbL₃ with HL = tropolone (1), 2-pyridinol-N-oxide (2) or, 3-hydroxy-1,2-dimethyl-4(1H)-pyridone (3) are obtained in good yield by one step reactions from commercially available hydrated niobium(V) oxide in aqueous media. The products are characterized by elemental analysis, FT-IR spectroscopy, NMR spectroscopy (¹H- and ¹³C-) and thermogravimetry. The crystal structure of oxotris(2-pyridinolato-N-oxide)niobium(V) is determined by single crystal X-ray diffraction, showing discrete molecules with pentagonal bipyramidal coordinated niobium. The ¹H-NMR spectra of CDCl₃ solutions indicate a fluxional behaviour for the three complexes.     

Zweikernige Antimon(V)-Komplexe mit Diphenylphosphato-Brückenliganden

Binuclear Antimony(V) Complexes with Bridging Diphenylphosphato Ligands The binuclear antimony(V) complexes Cl₃Sb(O)[(C₆H₅O)₂PO₂]₂SbCl₃ ( 1 ), Cl₃Sb(O)[(C₆H₅O)₂PO₂](OCH₃)SbCl₃ ( 2 ), Cl₃Sb(O)[(C₆H₅O)₂PO₂](OH)SbCl₃ ( 3 ) and Cl₄Sb[(C₆H₅O)₂PO₂]₂SbCl₄ ( 4 ) are prepared by reaction of diphenylphosphoric acid with antimony(V) chloride, water and methanol in different molar ratios. The progress of the reactions was controlled by the ³¹P-NMR signals. 1 crystallizes triclinic in the space group P1 with a = 918.8, b = 1312.9, c = 1395.8 pm, α = 91.91, β = 101.36, γ = 95.90° and Z = 2. 2 to 4 crystallize in monoclinic space groups: 2 : C2/c, a = 2753.4, b = 1156.1, c = 1476.7 pm, β = 98.01° and Z = 8; 3 : P2₁/c, a = 1234.8, b = 1471.8, c = 1263.4 pm, β = 107.15° and Z = 4; 4 : P2₁/n, a = 1943.8, b = 940.8, c = 2015.6 pm, β = 109.87° and Z = 4 resp. The NMR spectra are discussed and some IR data are communicated.     

Simultaneous Kinetic‐Spectrophotometric Determination of Nb(V) and Ta(V) Using H‐Point Standard Addition Method

A simple, rapid, precise and accurate kinetic method for simultaneous spectrophotometric determination of Nb(V) and Ta(V) is described. This method is based on the difference between the rate of the reaction of Nb(V) and Ta(V) with 4‐(2‐pyridylazo)resorcinol (PAR) in the presence of tartaric acid. H‐point standard addition method (HPSAM) was used to resolve the mixtures. The results showed that Nb(V) and Ta(V) can be determined simultaneously in the ranges of 0.10–5.0 and 0.50–12.0 μg mL^?;1, respectively. The proposed method was successfully applied to the simultaneous determination of Nb(V) and Ta(V) in several alloy samples.     

Hydroxonium-hexachloroantimonate(V)

Hydroxonium Hexachloroantimonates(V) The hydroxonium hexachloroantimonates(V) H₅O₂⊕SbCl₆? (I), H₇O₃⊕SbCl₆? (III), H₉O₄⊕SbCl₆? (V) as well as the deuterated compounds D₅O₂⊕SbCl₆? (II), D₇O₃⊕SbCl₆? (IV) and D₉O₄⊕SbCl₆? (VI) were prepared by reaction of hydrogen chloride resp. deuterium chloride with water addition compounds of antimony(V) chloride. The i.r. spectra are discussed.     

Phosphorus(V)-catalyzed deoxydichlorination reactions of aldehydes

A phosphine oxide-catalyzed conversion of aldehydes into 1,1-dichlorides is reported. The reaction proceeds via a phosphorus(V)-catalysis manifold in which phosphine oxide turnover is achieved using oxalyl chloride as a consumable reagent. The new method is applicable to a range of aldehydes and, in combination with palladium-catalyzed reductive dimerization, gives rise to a new catalytic approach to the synthesis of stilbenes and a short formal synthesis of resveratrol.     

Tantal (V)

Ohne Zusammenfassung