Reactivity of the perhaloalkanes CF2BrX (X:Cl,Br) with nucleophiles. Part 5. Condensation with potassium 2-allyl phenoxide ; evidence for difluorocarbene formation

BrCF₂CF₂Br reacts easily with various potassium thiophenoxides and phenoxides to give respectively 2-bromo tetrafluoroethyl thioethers and ethers. The lipophilicity of C₆H₅SCF₂CF₂Br and C₆H₅OCF₂CF₂Br is measured and compared with that of the well known C₆H₅SCF₂CF₂H and C₆H₅OCF₂CF₂H.     

Synthese de composes aromatiques comportant les groupements OCF2Br et SCF2Br—II : Action de CF2Br2 et de cf2brcl sur des thiophenates et phenates de potassium diversement substitues

The reaction of dibromodifluoromethane and bromochlorodifluoromethane with substituted potassium thiophenoxides and phenoxides leads to the formation of new aromatic compounds bearing OCF₂Br and SCF₂Br groups.     

Solubility in the Na2Cr2O7-(NH4)2Cr2O7-K2Cr2O7-H2O system

Solubility in the Na₂Cr₂O₇-(NH₄)₂Cr₂O₇-K₂Cr₂O₇-H₂O four-component water-salt system at 25, 50, and 75°C was studied for the first time. Phase field boundaries for individual salts and potassium and ammonium dichromate solid solutions, monovariant lines, and invariant points were determined. Experimental data were used to optimize the looped isohydric process of potassium dichromate preparation involving additional salts.     

Studies on furan derivatives. XII. Nucleophilic substitution of methyl 5-nitro-2-furancarboxylate. Preparation of methyl 5-phenoxy-2-furancarboxylates

Twenty one methyl 5-phenoxy-2-furancarboxylates prepared from the reaction of methyl 5-nitro-2-furan-carboxylate with phenoxides via displacement of the nitro group. In the reaction of potassium 2-nitrophen-oxide with methyl 5-nitro-2-furancarboxylate at 110°-120°, 2,2′-dinitrodiphenyl ether was obtained as a main product.     

Synthesis and characterization of methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER3)] (SS = S2CNR 2, S2COEt, S2P(OR)2, S2 PPh2; ER3 = PMePh2, PPh3, AsPh3)

Methylpalladium(II) dithiolate complexes of the type [PdMe(SS)(ER₃] (SS = S₂ CNR₂ (R = Me or Et), S₂COEt, S₂P(OR)₂ (R = Et, ⁿPr, ⁱPr), S₂PPh₂; ER₃ = PMePh₂, PPh₃, AsPh₃) have been synthesized by the reaction of [Pd₂Me₂(μ-Cl)₂(PMePh₂)₂] with sodium/potassium/ammonium salts of the dithio acid or by treatment of [PdMeCl(cod)] with ER₃ followed by sodium/potassium/ammonium salts of the dithio ligand. All the complexes were characterized by elemental analysis, IR and nuclear magnetic resonance (¹H, ³¹P) data.     

Electrical properties of K2FeCl5·H2O and K2AlF5

The electrical conductivity of nominally pure K₂FeCl₅·H₂O and anhydrous K₂AlF₅ has been studied from 300 to 690°K. K₂FeCl₅·H₂O exhibits mixed ionic and electronic conduction, whereas K₂AlF₅ is a pure ionic conductor. The mass and charge transport processes in K₂FeCl₅·H₂O seem to be governed by deviations from both molecularity and stoichiometry. At elevated temperatures both potassium and chloride ions are mobile in K₂FeCl₅·H₂O.     

A new bismuth potassium nitrate oxide, Bi1.7K0.9O2(NO3)2: Synthesis, structure, thermal behavior, and photocatalytic properties

We report here the first observation of a bismuth potassium nitrate Bi_1.7K_0.9O₂(NO₃)₂, obtained via thermal decomposition of bismuth and potassium nitrate mixtures. The new compound is orthorhombic, space group Immm (71), Z = 2, with a = 3.8698(7) Å, b = 3.8703(7) Å, and c = 24.1271(4) Å. Its crystal structure was refined from powder X-ray diffraction data by analogy with the mineral beyerite, Bi₂O₂Ca(CO₃)₂. The morphology and elemental composition of Bi_1.7K_0.9O₂(NO₃)₂ were characterized using scanning electron microscopy (SEM) with energy dispersive X-Ray spectroscopy (EDS). Its phase transformations upon heating and products of its thermal decomposition were studied using XRD, TGA and FTIR. At 440 °C, Bi_1.7K_0.9O₂(NO₃)₂ transforms to another basic bismuth potassium nitrate with demonstrates a very similar XRD pattern but slightly larger cell parameters. At 520 °C, the intermediate oxide nitrate decomposes into a mixture of crystalline α-Bi₂O₃ and KNO₃. The as prepared Bi_1.7K_0.9O₂(NO₃)₂ showed lower than TiO₂ (Degussa P25) photocatalytic activity upon decomposition of a widely used model pollutant, Rhodamine B (RhB) and photooxidation of potassium iodide under UV-vis light irradiation. Interaction with potassium iodide in alkaline media resulted in formation of Bi₅O₇I.     

K2Li(NH2)3 and K2Na(NH2)3—synthesis and crystal structure of two crystal-chemically isotypic mixed-cationic amides

K₂Li(NH₂)₃ (1) was the only crystalline product obtained from the reaction of potassium with dilithium decahydro-closo-decaborate Li₂B₁₀H₁₀ in liquid ammonia at −38 °C. The compound crystallizes in the space group P4₂/m with Z=4, a=6.8720(5) Å, c=11.706(1) Å and V=552.81(7) Å³. The investigated crystal-chemically isotypic sodium compound K₂Na(NH₂)₃ (2) was merohedrally twinned and crystallized from a reaction mixture containing potassium and disodium decahydro-closo-decaborate Na₂B₁₀H₁₀ in liquid ammonia with a=7.0044(5) Å, c=12.362(1) Å and V=606.48(9) Å³. The compounds contain pairs of edge sharing tetraamidolithium or tetraamidosodium tetrahedra which are interconnected by potassium ions forming three-dimensional infinite networks.     

Solid potassium-cation-conducting electrolytes in the systems K2?2 x Fe2? x A x O4 (A = Nb, Ta)

Highly conductive potassium-cation solid electrolytes based on potassium monoferrite with cations Nb⁵⁺ and Ta⁵⁺ partially replacing cations Fe³⁺ are synthesized and studied. Both additives cause a sharp increase in the conductivity of KFeO₂ at temperature below ∼700°C. The two solid electrolytes have similar electric characteristics, which is apparently associated with the close sizes of the doping cations. The increase in the conductivity of potassium monoferrite with the introduction of dopants studied is associated with the formation of potassium vacancies at the substitution Fe³⁺ → Nb⁵⁺ (Ta⁵⁺) + 2 V′_c and also with the elimination of a phase transition typical of pure KFeO₂. Original Russian Text ? E.I. Burmakin, G.Sh. Shekhtman, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 9, pp. 1035–1038. The paper was submitted for the special issue devoted to high-temperature electrochemistry.     

Les bronzes de cobalt KxCoO2 (x < 1). L'oxyde KCoO2

The reaction between potassium and cobalt oxides leads to two bronze-type phases with formula K_xCoO₂ (x = 0.50 and x = 0.67), and to a KCoO₂ oxide with two allotropic forms. The lattice of K_xCoO₂ is built up by sheets of (CoO₂)_n octahedra between which potassium ions are inserted with a prismatic coordination; they have a metallic behavior. The structures of both KCoO₂ varieties are related to the cristobalite type. The oxidation state of cobalt is discussed on the basis of structural, optical, and magnetical data.     

Synthesis and CO2 capture evaluation of Li2−xKxZrO3 solid solutions and crystal structure of a new lithium-potassium zirconate phase

Solid solutions of lithium and potassium metazirconates Li_2−xK_xZrO₃ (where, 0?x?2) were prepared by coprecipitation. Samples were characterized by powder X-ray diffraction, scanning electron microscopy, and thermogravimetric analyses. Results showed that the solubility limits of potassium into Li₂ZrO₃ is x=0.2. Furthermore, at higher potassium concentrations, a new phase was synthesized, Li_2.27K_1.19Zr_2.16O_6.05. For structural studies of this new phase, XRD data were analyzed by Rietveld refinements. Additionally, at high potassium concentrations different phases of ZrO₂ were found, as potassium tends to sublimate. On the other hand, lithium-potassium metazirconate solid solutions, Li_2−xK_xZrO₃, were tested as CO₂ captors. Thermal analyses into a CO₂ flux showed that Li_2−xK_xZr₂O₃ solid solutions present a better CO₂ absorption than Li₂ZrO₃ pure. The differences observed in the CO₂ sorption processes were explained with thermodynamic data.     

Synthesis and structural characterization of ferrocene-based bis(pyrazol-1-yl)borate ligands: FcB(Me)pz2K, Fc2Bpz2K, and 1,1′-fc[B(Me)pz2]2K2 (Fc: ferrocenyl, fc: ferrocenylene, pz: pyrazolyl)

Reaction of the ferrocenyl(dimethylamino)boranes FcB(Me)NMe₂, Fc₂BNMe₂, and 1,1′-fc[B(Me)NMe₂]₂ with 1:1 mixtures of pyrazole and potassium pyrazolide in refluxing THF gave the potassium salts of the ferrocene-based bis(pyrazol-1-yl)borate ligands FcB(Me)pz₂K, Fc₂Bpz₂K, and 1,1′-fc[B(Me)pz₂]₂K₂ in good yield (Fc: ferrocenyl, fc: ferrocenylene, pz: pyrazolyl). In the solid state, FcB(Me)pz₂K and Fc₂Bpz₂K form centrosymmetric dimers with short K?Cp contacts suggesting an η⁵ coordination mode of the potassium ion. The crystal lattice of the ditopic ligand 1,1′-fc[B(Me)pz₂]₂K₂ consists of coordination polymer strands featuring essentially the same structural motif that has been observed for the monotopic derivatives. All three scorpionate ligands are thus promising building blocks for the preparation of ferrocene-containing multiple-decker sandwich complexes.     

Syntheses, crystal and electronic structures of three new potassium cadmium(II)/zinc(II) tellurides: K2Cd2Te3, K6CdTe4 and K2ZnTe2

Three new ternary potassium(I) zinc(II) or cadmium(II) tellurides, namely, K₂Cd₂Te₃, K₆CdTe₄ and K₂ZnTe₂, were synthesized by solid-state reactions of the mixture of pure elements of K, Cd (or Zn) and Te in Nb tubes at high temperature. K₂Cd₂Te₃ belongs to a new structure type and its structure contains a novel two-dimensional [Cd₂Te₃]²⁻ layers perpendicular to the b-axis. K(5) cation is located at the center of five member rings of the 2D [Cd₂Te₃]²⁻ layer, whereas other K⁺ cations occupy the interlayer space. K₆CdTe₄ with a K₆HgS₄ type structure features a “zero-dimensional” structure composed of isolated CdTe₄ tetrahedra separated by the K⁺ ions. K₂ZnTe₂ in the K₂ZnO₂ structural type displays 1D [ZnTe₂]²⁻ anionic chains of edge sharing [ZnTe₄] tetrahedra separated by the potassium(I) ions. K₂Cd₂Te₃, K₆CdTe₄ and K₂ZnTe₂ revealed a band gap of 1.93, 2.51 and 3.0 eV, respectively.     

Synthesis, characterization, and structural study of K2FeZrP3O12 with the langbeinite structure

A potassium iron zirconium phosphate, K₂FeZrP₃O₁₂, was synthesized by thermal treatment of a material obtained by the sol-gel method, mixing two aqueous solutions, the first containing KCl, FeCl₃ and ZrOCl₂, and the second, H₃PO₄. The crystal structure was refined using powder X-ray diffraction data. The unit cell is cubic, a=10.0554(3) Å, space group P2₁3. This compound is the first iron zirconium phosphate described with a langbeinite-type structure.     

Solid potassium-cation-conducting electrolytes in the K1?2xBaxFeO2 and K1?2xPbxFeO2 systems

Novel highly conductive potassium-cation solid electrolytes based on potassium monoferrite are synthesized via partial substitution of Ba²⁺ and Pb²⁺ for K⁺ and studied. Both additives lead to an abrupt increase in the conductivity of KFeO₂. In the barium-containing system, the conductivity is slightly higher and the activation energy is somewhat lower. This can be explained by the effect of dimensional factor, because the Ba²⁺ cation is larger than the Pb²⁺ cation. The reasons for the conductivity increase in potassium monoferrite upon introducing the additives are the formation of potassium vacancies in the course of substitution K⁺ → M²⁺ + V’_K and the extension of temperature range of existence of the high-temperature KFeO₂ modification. Original Russian Text ? E.I. Burmakin, G.V. Nechaev, G.Sh. Shekhtman, 2007, published in Elektrokhimiya, 2007, Vol. 43, No. 1, pp. 125–128.     

Condensation of 1,2-dibromotetrafluoroethane with various potassium thiophenoxides and phenoxides

BrCF₂CF₂Br reacts easily with various potassium thiophenoxides and phenoxides to give respectively 2-bromo tetrafluoroethyl thioethers and ethers. The lipophilicity of C₆H₅SCF₂CF₂Br and C₆H₅OCF₂CF₂Br is measured and compared with that of the well known C₆H₅SCF₂CF₂H and C₆H₅OCF₂CF₂H.     

Novel microporous zirconium silicate (K2ZrSi3O9·2H2O) from high temperature phase transformation

A new microporous zirconosilicate K₂ZrSi₃O₉·2H₂O (AV-15) has been prepared by high-temperature phase transformation at 910 °C. Its structure has been determined ab initio from powder X-ray diffraction data. The unit cell is orthorhombic, space group C222₁ (no. 20), Z=4 with cell dimensions: a=8.105(3), b=10.684(5), c=12.030(5) Å, V=1041.76(7) Å³. The framework connection of AV-15 is essentially the same as the previously reported sodium stannosilicate AV-10 while the locations of potassium and water molecules in the former are quite different from those of the sodium and water molecules in AV-10. In AV-10 sodium and water molecules form a sinucoidal chain, while potassium and water molecules build up a linear chain in AV-15. The water molecules in AV-15 are lost on heating with a typical zeolitic behaviour. SEM shows that the particle sizes and habits of AV-15 and parent umbite material are the same. The ²⁹Si MAS NMR spectrum of AV-15 displays two resonances at ca. −89.4 and −90.1 ppm in a 1:2 intensity ratio. Thermogravimetry analysis confirms the existence of water in this material.     

Excitation of alkali atoms in collisions with molecules. Population of the states K(62S) and K(52-P)

Radiation at 4050 and 6930 A has been observed in collisions of fast potassium atoms with N₂, O₂, CO, NO, CO₂, C₂H₄ and C₆H₆. Emission at both wavelengths is weak compared to that at 7680 Å. The threshold energy for emission at 6930 Å has been found to be equal to the excitation energy (3.4 eV) of the state K(6²S) for N₂ and NO, but higher (5.5 eV) for CO.     

Preparation and properties of potassium pentafluorodioxo-tungstate (VI) K3WO2F5 and potassium octafluoropentaoxo-ditungstate (VI) K6W2O5F8

The potassium salts of two new hepta coordinated oxyfluoro anions of tungsten (VI) are reported in this paper. The monomer, K₃WO₂F₅ was obtained from the aqueous solution while the dimer, K₆W₂O₅F₈ was isolated from alcohol. The absorption peak of K₆W₂O₅F₈ at 830 cm^-1 has been attributed to W-O-W link. The W-O-W angle is found to be 155° and the force constant is 4.44 mdyn/A°. The d values obtained from x-ray powder diffraction studies are given.     

Preparation and thermal stability of trioxalatocobaltates of bivalent metals KM2+ [Co(C2O4)3]·xH2O

Trioxalatocobaltates of bivalent metals KM²⁺[Co(C₂O₄)₃]·x H₂O, with M²⁺ = Ba, Sr, Ca and Pb, have been prepared, characterized and their thermal behaviour studied. The compounds decompose to yield potassium carbonate, bivalent metal carbonate or oxide and cobalt oxide as final products. The formation of the final products of decomposition is influenced by the surrounding atmosphere. Bivalent metal cobaltites of the types KM²⁺CoO₃ and M²⁺CoO_3—x are not identified among the final products of decomposition. The study brings out the importance of the decomposition mode of the precursor in producing the desired end products.