Crystal structure of tetramethylammonium hexafluoridoniobate(V) and hexafluoridotantalate(V)

Crystal structures of newly synthesized tetramethylammonium hexafluoridoniobate(V) and hexafluoridotantalate(V) (CH₃)₄N[МF₆] (M=Nb, Ta) have been determined; they crystallize in the tetragonal crystal system, sp. gr. P4/nmm. Crystal structures of isostructural compounds (CH₃)₄N[МF₆] (M=Nb, Ta) are formed by virtually regular tetrahedral tetramethylammonium cations (CH₃)₄N⁺ (NMe₄, TMA) and octahedral complex anions [МF₆]^– (M=Nb, Ta), fluorine atoms of the equatorial plane are statistically disordered over two positions. Ionic interactions and weak hydrogen bonds C–H???F join the cations and the complex anions in a 3D assembly.     

Liquid-liquid extraction of Mo(VI) and V(V) by Primene JMT

The extraction equilibrium of pentavalent vanadium and hexavalent molybdenum with a benzene solution of primary amine Primene JMT sulphate has been investigated. The comparison of the extraction of aqueous solutions containing the salts of the elements and the solutions containing the mixture of Mo(VI) and V(V) was carried out. The attention was directed to the pH 2–6 region in which the heptamolybdates and decavanadates in prevail aqueous phase and to the region ≈1M H₂SO₄ which was suitable for the extraction separation of Mo(VI). The mechanism of extraction is discussed.     

Tungsten(V) dimeric complexes with heterocyclic dithiocarbamates

In this paper we report the syntheses and study of a number of oxo- and sulphido-bridged tungsten(V) complexes with morpholine dithiocarbamate and piperidine dithiocarbamate as ligands. We assign the following formulae to the complexes: W₂O₃(Rdtc)₄, W₂O₄(Rdtc)₂, W₂O₂S₂(Rdtc)₂ and W₂O₃S(Rdtc)₂ (where R = morpholine and piperidine), based on the analytical data. We have studied the complexes by IR and electronic spectra, and magnetic susceptibility measurements. We assign in the IR spectra the following bands: W=O (ν_s=939–948 cm^?1), W-O_b(ν_a=813–819 cm^?1, ν_s = 431–448 cm^?1), W-S_b (ν_a=470–476 cm^?1, ν_s = 368–370 cm^?1, C-N (β = 1511–1519 cm^?1) and C-S (ν = 1090–1113 cm^?1). The low values of the magnetic moments (0.03–0.60 B.M.) are in accordance with a dimeric species of tungsten(V).     

Reactions of Nitridotechnetium(V) Complexes with Boranes

Nitrido bridges between technetium and boron were formed during reactions of [TcN(PMe₂Ph)(Et₂dtc)₂] (Et₂dtc^? = diethyldithiocarbamate) and BH₃ or BPhCl₂ at low temperatures. X‐Ray structure determinations show that the products contain almost linear Tc–N–B bonds with Tc–N distances which are only slightly lengthened with respect to the triple bonds in the precursor molecule. However, a significant lengthening of the Tc–S bond trans to the nitrido ligand is detected by the decrease of the structural trans influence of “N^3?”N. The compounds are instable and decompose at room temperature under cleavage of the N–B bonds. A reaction between [TcNCl₂(PPh₃)₂] and BCl₃ does not yield a product with a nitrido bridge. Prolonged heating in dichloromethane results in decomposition of the technetium complex and the formation of (HPPh₃)₂[TcCl₆]. Hydrogen bonds are established between the complex anion and each two counter ions.     

Crystal structure and NMR study of 4-amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V)

4-Amino-1,2,4-triazolium hexafluoridoniobate(V) and hexafluoridotantalate(V) (C₂H₅N₄)MF₆ (M = Nb, Ta) crystallizing in the monoclinic system (space group P2₁/n) are synthesized for the first time and their crystal structures and spectroscopic features are studied by single crystal X-ray diffraction and ¹H and ¹⁹F NMR spectroscopy. The crystal structures of isostructural (C₂H₅N₄)MF₆ compounds are formed of octahedral complex [MF₆]^– anions (M = Nb, Ta) and monoprotonated heterocyclic 4-amino-1,2,4-triazolium cations (C₂H₅N₄)⁺ organized in a three-dimensional structure via N–H···F and N–H···N hydrogen bonds. The character and types of ion motions in the fluoride sublattice of (C₂H₅N₄)MF₆ are determined in a wide temperature range.     

Triphenylarsenic(V) and -antimony(V) derivatives of multidentate Schiff bases: synthesis,characterization, and antimicrobial activities

Equimolar reactions of Ph _n M(OPr ⁱ )₂ (where M?=?As and Sb) with Schiff bases [OHC₆H₄CH=N(R)OH] in benzene solution yield organoarsenic and -antimony derivatives, (where M?=?As and Sb; n?=?1 and 3; R?=?–CH₂CH(CH₃)–, –(CH₂)₃–, –(CH₂)₂–, and –C(CH₃)₂CH₂–). All these derivatives have been characterized by elemental analyses and molecular weight measurements, and structures have been proposed on the basis of IR, NMR (¹H and ¹³C), and FAB-mass studies. Schiff bases and their corresponding organoantimony derivatives have been screened for antimicrobial activity against Aspergillus flavus (fungus) and Escherichia coli (bacteria).     

Newly designed Mn (III)–W(V) bimetallic assembly built by manganese (III) Schiff–base and octacyanotungstate(V) building blocks: Structural topologies,and magnetic features

New complex [Mn (SB)₂(DMF)₂] [W (CN)₈] hereafter referred to as complex 1 , which was prepared by self–assembly of [Mn (SB)₂(DMF)₂]³⁺ and [W (CN)₈]³⁻ and structurally characterized by elemental analysis, infrared (IR) and single crystal X–ray techniques (H₂SB is Schiff base derived from the condensation of salicylaldehyde and N,N–diethylethylenediamine and DMF is dimethylformamide). The structure consists of 1–D supramolecular chains and further stacks to give a 3–D supramolecular architecture whose molecular fragments are linked by hydrogen bond as well as C − H···π interactions between [Mn (SB)₂(DMF)₂]³⁺ and [W (CN)₈]³⁻. An underlying net for the representation consists of two types of fragments with 1,4 M5–1 and 1,8 M9–1 topologies and further illustration of the molecular network in terms of a graph−theory approach using simplification procedure resulted in the underlying net of 2C1topological type in the complex 1 . Magnetic susceptibility measurements of complex 1 was carried out in the temperature range 2–300 K, indicates the presence of either magnetic anisotropy zero field splitting, the effect of intramolecular interactions, or both. Complex 1 follows the Curie–Weiss law with Curie constant value of 3.43 cm³mol⁻¹K, and the slight negative Weiss constant (−0.60 K) value indicates the predominant antiferromagnetic magnetic exchange interactions. The magnetic properties of Title complex was investigated thoroughly and showed that ferromagnetic interaction between W(V) and Mn (III) operate via the intramolecular H–bonding interaction between cyanide nitrogens and a hydrogen atom.     

Thermolyse von Phosphor(V)-Schwefel(VI)-nitridhalogeniden

Thermolysis of Phosphorus(V) Sulfur(VI) Nitride Halides Thermolysis of compounds of the type R₂PCl = N–SO₂X (R = Cl, CH₃, C₆H₅; X = F, Cl) results in the formation of the compounds R₂P(O)Cl and [NS(O)X]_n. Pyrolysis of the title compounds with longer chains yields, among others, the cyclic compounds III and IX. IX is also one of the decomposition products of a sulfamide derivative (XXI). Finally the thermal behaviour of carbon containing phosphorus(V) sulfur(VI) nitride chlorides has been investigated.     

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).     

Homodinuclear glycolate derivatives of bismuth(V) and arsenic(III): synthesis and spectroscopic studies

Ligand bridged homodinuclear derivatives of bismuth(V) of the type, (1a–1d) [where R =–C(CH₃)₂CH₂CH(CH₃)–(1a),–CH(CH₂CH₃)CH₂–(1b),–CH(CH₃)CH(CH₃)–(1c),–CH(CH₃)CH₂–(1d)] have been synthesized by reactions of equimolar oxobis(triphenylbismuth)dichloride, {[Ph₃Bi]₂O}Cl₂ with glycols, HOROH in the presence of NaOMe. Reactions of sodiumtetraisopropoxoarsonate, NaAs(OPrⁱ)₄ with in 1 : 1 molar ratio yielded homodinuclear alkoxo derivatives of arsenic(III) containing glycols, (2a–2d). All compounds were characterized by elemental analysis, molecular weight determinations, IR and NMR (¹H and ¹³C) spectral studies.     

Über die Reaktion von Trimethylamin mit Antimon(V)-chlorid

Inhaltsübersicht. Trimethylamin und Antimon(V)-chlorid bilden keinen Dornor-Acceptor Komplex. In Abhängigkeit vom Molverhältnis reagieren die Komponenten zu (CH₃)₃NCl⁺SbCl₆^– (I) bzw. zu (CH₃)₃NH+X^– und (CH₃)₂N=CH₃⁺X^– (X^– = SbCl₆^–, SbCI₄^–, Sb₃CI₁₄^3– und CI^–). I kann in (CH₃)₃NH⁺SbCl₆^– und (CH₃)₂N=CH₂+SbCl₆^– zerfallen. The Reaction of Trimethylamine with Antimony (V) Chloride Abstract. Trimethylamine and antimony(V) chloride forms no donor-acceptor-complex. In dependence of the molar ratio the compounds reacts to (CH₃)₃NCl⁺SbCl₆^– (I) resp. to (CH₃)₃NH+X^– and (CH₃)₂N=CH₃⁺X^– (X^– = SbCl₆^–, SbCI₄^–, Sb₃CI₁₄^3– and CI^–). I can decompose into (CH₃)₃NH⁺SbCl₆^– and (CH₃)₂N=CH₂+SbCl₆^–.     

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.     

Monodentate imido coordination of 2-aminodiphenylamine to rhenium(V)

The complex trans-[Re(ada)Cl₃(PPh₃)₂] (H₂ada?=?2-aminodiphenylamine) was prepared from the reaction of trans-[ReOCl₃(PPh₃)₂] with H₂ada in acetonitrile. The ligand ada is coordinated to the rhenium(V) centre solely through a dianionic imido nitrogen, with distorted octahedral coordination geometry around the metal ion. Surprisingly, the Re–Cl bond trans to the Re=N bond is shorter than the two equatorial Re–Cl bonds. The Re?=?N–C bond angle of the phenylimido moiety equals 178.7(4)°.     

Raman spectra and the dynamic structure of the high pressure phase of NH4Br (V) and ND4Br (V)

Similar Raman spectra are observed at high pressures for phases II and V of ND₄Br and NH₄Br. Deuteration lowers the II–V phase transition from 20 to 9 kbar at 296 K. ND₄Br V and NH₄Br V are interpreted as mixed phases, and their spectra as the superposition of the spectra of two other phases, III (antiparallel arrangement of the NH₄⁺ ions) and IV (parallel arrangement). The phonons which become Raman inactive at the V–IV phase transition are assigned to clusters or domains of phase V which have antiparallel arrangement.     

Die Schwingungsspektren des Chlortrimethylammonium-chlorids und -hexachloroantimonats(V)

Inhaitsübersicht. Die Schwingungsspektren von (CH₃)₃NCI₂ (I) und (CH₃)₃NCl⁺SbCI₆^– (II) wurden aufgenommen und im Hinblick auf die N—Cl-Bindungsverhältnisse diskutiert. The Vibrational Spectra of Chlorotrimethylammonium Chloride and Hexachloroantimonate(V) Abstract. The vibrational spectra of (CH₃)₃NCl₂ (I) und (CH₃)₃NCl⁺SbCl₆^– (II) are measured and discussed in view of the N-Cl bonds. Die IR-Spektren der nach [9] dargestellten Verbindungen wurden als Verreibungen in Nujol bzw. Hostaflonöl mit einem linear in Wellenzahlen registrierenden IR-Spektrophotometer PE 457 (Perkin Elmer) aufgenommen. Die Raman-Spektren wurden mit einem Coderg-Laser-Gerät PHO vermessen. Zur Anregung wurde die 4880 Å-Linie eines Argon-Gaslasers verwendet.     

Palladium-catalyzed coupling of tetraphenylbismuth(V) derivatives with methyl acrylate

Tetraphenylbismuth(V) derivatives of the general formula Ph₄BiX [X = OSO₂C₆H₄Me-4, OC₆H₂(NO₂)₃-2,4,6, OC₆H₂(NO₂-4)(Br₂-2,6), OSO₂C₆H₃(OH)(COOH)] react with methyl acrylate in the presence of palladium dichloride (1:3:0.04 molar ratio) in acetonitrile at 20°C to form the cross-coupling products, methyl cinnamate (0.17–0.54 mol mol^?1 starting bismuth compound) and methylhydrocinnamate (0.10–0.73 mol mol^?1), diphenyl (0.06–0.80 mol mol^?1), and benzene (0.02–0.36 mol mol^?1). The highest C-phenylating activity is shown by Ph₄BiOSO₂C₆H₄Me-4. The mechanisms with the palladium-catalyzed cross-coupling reactions are suggested.     

Differential determination of antimony(III) and antimony(V) by indirect spectrophotometry with chromium(VI) and diphenylcarbazide,after reduction of antimony(V)

Antimony(III) is determined indirectly through its reaction with excess of chromium(VI), the excess being quantified with diphenylcarbazide and measurement at 540 nm. Antimony(V) is reduced to antimony(III) with sodium sulfite in hydrochloric acid solution; excess of sulfite is eliminated by boiling. The subsequent determination of antimony(III) gives the concentration of total antimony, and antimony(V) is found from the difference between the results before and after reduction. Antimony in its different oxidation states can be determined in the range 0.04–0.7 mg l^?1 within an error of about 10%.     

Cationic Homoleptic Vanadium(II), (IV), and (V) Complexes Arising from Protonolysis of [V(NEt2)4]

At least three different cationic species arise in the classic protonolysis of [V^IV(NEt₂)₄] with a borate ammonium salt. The unexpected formation of the vanadium(V ) species [V(NEt₂)₄][B(C₆H₅)₄] (shown in the picture without its counterion) underlines the problem of deducing the true oxidation state of vanadium species in Ziegler–Natta reactions.     

Vanadium(V) extraction from sulfuric acid solutions

We studied vanadium(V) extraction by di-2-ethylhexylphosphoric acid (DEHPA) from 1.0–12.0 M sulfuric acid. Optimal extraction parameters were determined. IR, ⁵¹V NMR, and electronic spectroscopy was used to determine the stoichiometry of the extracted complex and the reaction equation for vanadium(V) extraction by DEHPA. The equilibrium constant of vanadium(V) extraction by DEHPA was determined.     

Rapid and simple chromatographic separation of V(V) and V(IV) using KH-phthalate and their determination by flame atomic absorption spectrometry

A method was developed for the chromatographic separation of V(V) and V(IV) based on the different sorption forces of these vanadium species in C18 columns in presence of KH-phthalate. The vanadium species were detected with a flame atomic absorption spectrometer with acetylene/N₂O flame. The detection limits (3σ) of V(V) and V(IV) were 0.18 μg/mL and 0.15 μg/mL, respectively. The relative standard deviations (N = 5) are 4.2% and 3.4% for 20–20 μg/mL V(V) and V(IV), respectively. The sampling frequency is 75/h. Because of the special interaction occurring between phthalate and V(IV) on the C18 column and the acetylene/N₂O flame atomic absorption detection, practically no interferences can be detected even in large inorganic matrix.