Über die Verdampfungsthermodynamik und die Bildungsenthalpien von CaSe,SrSe und BaSe

On the Thermodynamics of Vaporization and the Enthalpies of Formation of CaSe, SrSe and BaSe The congruent vaporization of the solid compounds CaSe, SrSe and BaSe of stoichiometric composition was studied over the temperature ranges 1832?2138 K, 1862?2122 K and 1860?2158 K, respectively, by the Knudsen effusion weight-loss method. Using enthalpy and entropy data from the literature for gaseous M, MSe, Se₂ and Se (M = Ca, Sr, Ba) and estimated data for the standard entropies and enthalpy functions of solid MSe, it can be shown that within the given temperature ranges CaSe and SrSe vaporize predominatly to the atomic species, while in case of BaSe the mode of vaporization to the atoms and to the molecular species BaSe are of about equal importance. The Se₂-content of the gas phase is very small in all cases. The following second and third law enthalpies and entropies (indices II and III respectively) were derived for the vaporization to the gaseous elements: see “Inhaltsübersicht”. The following standard enthalpies of formation of MSe(s) were derived from the third law enthalpies (in kJ · mol^?1): CaSe: ?445 ± 44; SrSe: ?451 ± 42; BaSe: ?467 ± 44.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram,VIII. WOBr3, WOBr2-Bildungsenthalpie und thermische Zersetzung

WOBr₃ and WOBr₂ were prepared by chemical transport reactions. From the solution enthalpy of WOBr₃ in NaOH/H₂O₂ the formation enthalpy ΔH°(WOBr₃,f,298) = ?113,2(±0,9) kcal/Mol was calculated. The thermal decomposition of WOBr₃ proceeds primarly according to 2 WOBr₃ = WOBr₂ + WOBr₄. The decomposition of WOBr₂ may be described by the reaction 2 WOBr₂ = WBr₂ + WO₂Br₂. The interpretation of the decomposition equilibrium of WOBr₃ gives the values ΔH°(WOBr₂,f,298) = ?116,9(±5) kcal/Mol, and S°(WOBr₃,f,298) = 46(±5) cl.     

Über die Synthese von Erdalkalimetalldihalogeniden und die Strukturen von Ca3Br2CBN und Sr3Cl2CBN

On the Synthesis of Alkaline-Earth Dihalides and the Structures of Ca₃Br₂CBN and Sr₃Cl₂CBN The reaction of alkaline-earth carbonates with ammonium chloride or bromide yields alkaline-earth dihalides at relatively low temperatures (300°C). Ca₃Br₂CBN and Sr₃Cl₂CBN were synthesized in sealed niobium containers at 950°C from the metal, its dihalide, boron nitride and graphite. The crystal structure of Sr₃Cl₂CBN was refined from single crystal data. Sr₃Cl₂CBN crystallizes isotypic with Ca₃Cl₂CBN in the orthorhombic space group Pnma (No. 62) with a = 1448.4(2) pm b = 405.46(5) pm, c = 1170.0(1) pm. The lattice constants of Ca₃Br₂CBN and Sr₃Cl₂CBN were determined by orthorhombic indexing of the powder patterns (Ca₃Br₂CBN: a = 1444.3(2) pm, b = 390.64(6) pm, c = 1139.2(2) pm; Sr₃Cl₂CBN: a = 1444.0(4) pm, b = 405.27(8) pm, c = 1167.8(2) pm). There was no success in preparing homologues with Barium.     

Zum Sättigungsdruck von GaCl3 und InCl3

Saturation Pressure of GaCl₃ and InCl₃ The saturation pressure of GaCl₃ and InCl₃ was measured in a Membran Zero Manometer. The enthalpy and entropy of sublimation or evaporation were derived from the temperature functions of the partial pressure via the constants of dissoziation.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. I. Sättigungsdruck und Bildungsenthalpie von MoO2Br2 und MoO2CI2

Molybdenum dioxiddibromide and -dichloride have been prepared from MoO₂, Br₂, und Cl₂, respectively, and their chemical and thermochemival behaviour was studied. Their enthalpies of formation, ΔH°, have been determined from the solution enthalpies of MoO₂Br₂, and MOo₂Cl₂, in aqueous NaOH (data see ?Inhaltsübersicht”?). From their sublimation pressures, p, the enthalpies, ΔH° (subl.), and entropies, ΔS° (subl.), of sublimation have been evaluated (data see above).     

Über die Gasphasenstruktur von CF3NCl2 und die Darstellung von CF3NCl2F+MF6− (M = As,Sb) und CF2 = NClF+SbF6−

Gas Phase Structure of CF₃NCl₂ and Preparation of CF₃NCl₂F⁺MF₆^? (M = As, Sb) and CF₂ = NCl₂F⁺SbF₆^? The gas phase structure of CF₃NCl₂ is reported. The following skeletal parameters are derived (r_a-values, error limits are 3σ values): N? C = 1.470(6) Å, N? Cl = 1.733(3) Å, ClNCl = 111.5(4)° and ClNC = 107.6(5)°. CF₃NCl₂F⁺MF₆^? is prepared by fluorination of CF₃NCl₂ with XeF⁺MF₆^?. The same educt CF₃NCl₂ reacts with XeF⁺SbF₆^? at ?40°C to CF₂ = NClF⁺SbF₆^? under elimination of ClF.     

Synthese,Charakterisierung und Struktur von Mn3SiO4F2

Synthesis, Characterization, and Structure of Mn₃SiO₄F₂ Mn₃SiO₄F₂ was synthesized by chemical vapour transport in a temperature gradient (800 → 700 °C) using MnF₂ as precursor and iodine as transport agent. SiO₂ was provided from the wall of the used silica tubes. The chemical composition of the crystals was determined by EELS and EDX analysis. The structure of Mn₃SiO₄F₂ was determined and refined to R(|F|) = 0.039, wR(F²) = 0.087, respectively. The orthorhombic phase crystallizes in the space group Pnma (No. 62) with a = 10.758(2) Å, b = 9.145(1) Å, c = 4.850(1) Å and Z = 4. Two crystallographically different Mn‐atoms are surrounded by oxygene and fluorine octahedrally. Si is tetrahedrally surrounded only by oxygen. IR‐measurements proved that in Mn₃SiO₄F₂ no substitution of F^– by OH^– takes place as in the mineral norbergite (Mg₃SiO₄(OH,F)₂).     

Der Sättigungsdruck von NbCl4 und NbBr4

Vapour Pressure of NbCl₄ and NbBr₄ The vapour pressur of solid NbCl₄ has been determined spectralphotometrically near 600 K: . NbCl₄ is monomolecular in the gaseous state. In the same way the vapour pressure of NbBr₄ has been found: .     

Zur Konstitution von Ba2WO3F4 und Ba2MoO3F4

On the Structure of Ba₂Wo₃F₄ and Ba₂MoO₃F₄ Ba₂[WO_2/2O₂F₂]F₂ has been prepared for the first time as colourless single crystals (from powder, Au-tube, 680°C, 90 d). It crystallizes in the monoclinic (C c) crystal system with a = 1151.1, b = 938.2, c = 718.8 pm, ß = 126.17°, Z = 4. d_x = 6.17, d_pyk = 6.13 g · cm^?3. (Fourcirclediffractometer PW 1100, Fa. Philips, MoKα-, ω-2Θ-scan, 1832 I₀(hkl) R = 8.3, R_w = 7.4%). Parameters see in the text. The isotypic Ba₂MoO₃F₄ has been prepared as powder (a = 1147.5, b = 937.0, c = 725.1 pm, ß = 126.42°). The structure shows chains of (WO_2/2O₂F₂) groups along [001]. To establish O^2? and F^? on the positions IR and Raman Spectra are employed. The Madelung Part of Lattice Energy, MAPLE, is calculated and discussed.     

Struktur,Verzwillingung und Eigenschaften von Ce4Br3C4

Structure, Twinning, and Properties of Ce₄Br₃C₄ The new compound Ce₄Br₃C₄ can be prepared from Ce metal, CeBr₃ and C (3 : 3 : 2) at 1020 °C. It crystallizes in P 1 with a = 422.7(1) pm, b = 1103.4(3) pm, c = 1126.8(2) pm, α = 77.15(3)°, β = 90.13(2)° and γ = 84.42(3)°. The crystals are characteristically twinned, the twin law being (1 0 0, ¹/₂ –1 0, 0 0 –1). The crystal structure contains puckered layers of edge sharing Ce₆C₂ octahedra. The mean C–C distance in the C₂ units is 133(5) pm. Ce₄Br₃C₄ has at room temperature a specific resistivity of 100 mΩ cm and an effective magnetic moment of 2.55(3) μ_B (Ce³⁺).     

Darstellung und Kristallstruktur von Rb4Br2O und Rb6Br4O

Syntheses and Crystal Structures of Rb₄Br₂O and Rb₆Br₄O In the quasi‐binary system RbBr/Rb₂O, the addition compounds Rb₄Br₂O and Rb₆Br₄O are obtained by solid state reaction of the boundary components RbBr and Rb₂O. Crystals of red‐orange Rb₄Br₂O as well as of orange Rb₆Br₄O decompose immediately when exposed to air. Rb₄Br₂O (Pearson code tI14, I4/mmm, a = 544.4(6) pm, c = 1725(2) pm, Z = 2, 175 symmetry independent reflections with I_o > 2σ(I), R₁= 0.0618) crystallizes in the anti K₂NiF₄ structure type; Rb₆Br₄O (Pearson code hR22, R3c, a = 1307.8(3) pm, c = 1646.6(5) pm, Z = 6, 630 symmetry independent reflections with I_o > 2σ(I), R₁ = 0.0759) in the anti K₄CdCl₆ structure type. Both structures contain characteristic ORb₆‐octahedra and can be understood as expanded perovskites, following the general systematics of alkaline metal oxide halides.     

Darstellung und spektroskopische Charakterisierung der Fluorphosphonium-Salze X2FPSCH3+MF6− (X = Br,Cl; M = As,Sb) und XF2PSCH3+SbF6− (X = Br,Cl, F)

Preparation and Spectroscopic Characterization of the Fluorophosphonium Salts X₂FPSCH₃⁺MF₆^? (X = Br, Cl; M = As, Sb) and XF₂PSCH₃⁺SbF₆^? (X = Br, Cl, F) The preparation of the fluorophosphonium salts X₂FPSCH₃⁺MF₆^? (X = Br, Cl; M = As, Sb) and XF₂PSCH₃⁺SbF₆^? (X = Br, Cl, F) by methylation of the corresponding thiophosphorylhalides in the system CH₃F/SO₂/MF₅ (M = As, Sb) is reported. The new salts are characterized by their vibrational and NMR spectra.     

Synthese und Kristallstruktur von (NH4)3Cu4Ho2Br13. Weitere Bromide vom Typ (NH4)3Cu4M2Br13 (M = Dy?Lu,Y) und Rb3Cu4Ho2Br13

Synthesis and Crystal Structure of (NH₄)₃Cu₄Ho₂Br₁₃. Further Bromides of the (NH₄)₃Cu₄M₂Br₁₃ Type (M = Dy? Lu, Y) and on Rb₃Cu₄Ho₂Br₁₃ Single crystals of (NH₄)₃Cu₄Ho₂Br₁₃ were obtained for the first time from the reaction of CuBr with HoBr₃ which was contaminated with NH₄Br: cubic, space group Pn3 , Z = 2, a = 1101.71(5) pm. The crystal structure may be considered as a variant of the fluorite type according to [(HoBr₆)₄][(NH₄)₆(Cu₄Br)₂] ? Ca₄F₈. Pure products can be prepared from the binary halides in glass ampoules at 350°C. The bromides (NH₄)₃Cu₄M₂Br₁₃ (M = Dy? Lu, Y) and Rb₃Cu₄Ho₂Br₁₃ are isotypic with (NH₄)₃Cu₄Ho₂Br₁₃.     

Bildung von NaAl(PH2)4, NaAl(HPCH3)4 und die präparative Darstellung von H3Si?PH2 und seiner PH-haltigen Derivate

NaAl(PH₂)₄ is prepared by the reaction of NaPH₂ with AlCl₃ in diglyme according to equation (a) in ?Inhaltsübersicht”?. In the same way NaAl(HPCH₃)₄ is obtained from CH₃PH₂. Für obtainung the analogous compound LiAl(HPCH₃)₄, LiPHCH₃ was prepared acc. to equ. (b). NaAl(PH₂)₄ (soluble in diglyme) allows the formation of SiH- and PH₂-containing silylphosphines in preparative yields acc. to equ. (c). H₃SiBr, CH₃SiH₂Br, (CH₃)₂SiHBr and CH₃SiHCl₂ react with NaAl(PH₂)₄ to form H₃Si? PH₂, CH₃SiH₂? PH₂, (CH₃)₂SiH? PH₂ and CH₃SiH(PH₂)₂, respectively, in about 70% yield. By analogous reaction of NaAl(HPCH₃)₄ and LiAl(HPCH₃)₄ the compounds H₃Si? PHCH₃, CH₃SiH₂? PHCH₃, (CH₃)₂SiH? PHCH₃ and (CH₃)₃Si? PHCH₃ have been obtained. These reaarange acc. to equ. (d), silylphosphones richer in SiH reaaranging faster. ¹H and ³¹P n.m.r. spectra are reported.