The Equilibrium Partial Pressure of HgI2 over and Thermodynamic Properties of Hg3Te2I2 1)

The high temperature vaporization pattern of Hg₃Te₂I₂(s,l) shows four distinctly different regimes, similar to those of the HgTe vaporization. The most predominant species in the vapor phase in all four regimes is HgI₂(g), followed by Hg(g) and, possibly, Te₂I₂(g). The width of the “homogeneity range” of Hg₃Te₂I₂(s) was determined to be less than about 0.17 mole‐% HgI₂. Applying the second‐law method to the vaporization of HgTe‐saturated Hg₃Te₂I₂(s) at higher temperatures yields the heat and entropy of vaporization of 20.9 ± 2.3 (kcal/mole) and of 27.5 ± 2.8 (cal/mole K), respectively, with estimated total uncertainties of less than ± 5.8 (kcal/mole) and ± 7.6 (cal/mole K), at an average temperature of 722 K. With an estimated heat capacity function of Hg₃Te₂I₂(s) and estimated thermodynamic values for HgI₂‐saturated HgTe(s), the heat of formation and absolute entropy of Hg₃Te₂I₂(s) are computed to be = ?49.7 ± 1.1 (kcal/mole) and = 97.3 ± 1.4 (cal/mole K), with estimated total uncertainties of ± 8.3 (kcal/mole) and ± 14.0 (cal/mole K). The combined results of this investigation provide valuable information for the crystal growth of this material from the vapor and molten phase.     

Crystal Structure of the Mixed‐Valent Basic Mercury Nitrate HgI2(NO3)2·HgII(OH)(NO3)·HgII(NO3)2·4HgIIO [= Hg8O4(OH)(NO3)5]

Light‐yellow single crystals of the mixed‐valent mercury‐rich basic nitrate Hg₈O₄(OH)(NO₃)₅ were obtained as a by‐product at 85 °C from a melt consisting of stoichiometric amounts of (Hg^I₂)(NO₃)₂·2H₂O and Hg^II(OH)(NO₃). The title compound, represented by the more detailed formula Hg^I₂(NO₃)₂·Hg^II(OH)(NO₃)·Hg^II(NO₃)₂·4Hg^IIO, exhibits a new structure type (monoclinic, C2/c, Z = 4, a = 6.7708(7), b = 11.6692(11), c = 24.492(2) Å, β = 96.851(2)°, 2920 structure factors, 178 parameters, R1[F² > 2σ(F²)] = 0.0316) and is made up of almost linear [O‐Hg^II‐O] and [O‐Hg^I‐Hg^I‐O] building blocks with typical Hg^II‐O distances around 2.06Å and a Hg^I‐O distance of 2.13Å. The Hg₂²⁺ dumbbell exhibits a characteristic Hg‐Hg distance of 2.5079(7) Å. The different types of mercury‐oxygen units form a complex three‐dimensional network exhibiting large cavities which are occupied by the nitrate groups. The NO₃^? anions show only weak interactions between the nitrate oxygen atoms and the mercury atoms which are at distances > 2.6Å from one another. One of the three crystallographically independent nitrate groups is disordered.     

Präparation,Kristallstruktur und thermisches Verhalten der Quecksilber(I)phosphate α-(Hg2)3(PO4)2, β-(Hg2)3(PO4)2 und (Hg2)2P2O7

Contributions on Crystal Structures and Thermal Behaviour of Anhydrous Phosphates. XXIII. Preparation, Crystal Structure, and Thermal Behaviour of the Mercury(I) Phosphates α-(Hg₂)₃(PO₄)₂, β-(Hg₂)₃(PO₄)₂, and (Hg₂)₂P₂O₇ Light-yellow single crystals of (Hg₂)₂P₂O₇ have been obtained via chemical vapour transport in a temperature gradient (500 °C → 450 °C, 23 d) using Hg₂Cl₂ as transport agent. Characteristic feature of the crystal structure (P2/n, Z = 2, a = 9,186(1), b = 4,902(1), c = 9,484(1) Å, β = 98,82(2)°, 1228 independent of 5004 reflections, R(F) = 0,066 for 61 variables, 7 atoms in the asymmetric unit) are Hg₂²⁺-units with d(Hg1–Hg1) = 2,508 Å and d(Hg2–Hg2) = 2,519 Å. The dumbbells Hg₂²⁺ are coordinated by oxygen, thus forming polyhedra [(Hg1₂)O₄] and [(Hg2₂)O₆]. These polyhedra share some oxygen atoms. In addition they are linked by the diphosphate anion P₂O₇^4– (ecliptic conformation; ∠(P,O,P) = 129°) to built up the 3-dimensional structure. Under hydrothermal conditions (T = 400 °C) orange single crystals of the mercury(I) orthophosphates α-(Hg₂)₃(PO₄)₂ and β-(Hg₂)₃(PO₄)₂ have been obtained from (Hg₂)₂P₂O₇ and H₃PO₄ (c = 1%). The crystal structures of both modifications have been refined from X-ray single crystal data [α-form (β-form): P2₁/c (P2₁/n), Z = 2 (2), a = 8,576(3) (7,869(3)), b = 4,956(1) (8,059(3)), c = 15,436(3) (9,217(4)) Å, β = 128,16(3) (108,76(4))°, 1218 (1602) independent reflections of 4339 (6358) reflections, R(F) = 0,039 (0,048) for 74 (74) variables, 8 (8) atoms in the asymmetric unit]. In the structure of α-(Hg₂)₃(PO₄)₂ three crystallographically independent mercury atoms, located in two independent dumbbells, are coordinated by three oxygen atoms each. Thus, [(Hg₂)O₆] dimers with a strongly distorted tetrahedral coordination of all mercury atoms are formed. Such dimers are present besides [(Hg₂)O₅]-polyhedra in the less dense crystal structure of β-(Hg₂)₃(PO₄)₂ (d(Hg–Hg) = 2,518 Å). The mercury(I) phosphates are thermally labile and disproportionate between 200 °C (β-(Hg₂)₃(PO₄)₂) and 480 °C (α-(Hg₂)₃(PO₄)₂) to elemental mercury and the corresponding mercury(II) phosphate.     

Struktur und Eigenschaften von Doppelhalogeniden von substituiertem Ammonium und Quecksilber(II). VI [1]. Die Kristallstruktur von (CH3NH3)2HgBr4 und (CH3NH3)2HgI4

Structure and Properties of Double Halogenides of Substituted Ammonium and Mercury(II). VI. Crystal Structure of (CH₃NH₃)₂HgBr₄ and (CH₃NH₃)₂HgI₄ The compounds (CH₃NH₃)₂HgBr₄ and (CH₃NH₃)₂HgI₄ were prepared from stoichiometric mixtures of the methylammonium halogenides and the mercury(II) halogenides in methanol by evaporation. X-ray structure determination revealed for (CH₃NH₃)₂HgBr₄ monoclinic symmetry, space group P2₁/c and orthorhombic symmetry, space group Pbca for (CH₃NH₃)₂HgI₄. Both compounds are built from isolated, slightly deformed tetrahedra. The Hg? Br distances range from 2.586(3) Å to 2.598(2) Å, the Br? Hg? Br angles from 105.36(8)° to 112.26(8)°. The observed distances in the HgI₄ tetrahedra are in the range 2.751(1) and 2.803(1) Å, the I? Hg? I angles between 106.25(3)° and 115.68(4)°. The tetrahedra are linked together by hydrogen bonds between the methylammonium group and the halogen atoms.     

Beiträge zur Chemie der Oxidhalogenide von Molybdän und Wolfram. IX. Bildungsenthalpie und Sättigungsdruck des MoOBr3

From the enthalpy of solution of MoOBr₃ in NaOH/H₂O₂ the enthalpy of formation ΔH°(MoOBr₃,f,298) = ?109,5(±0,4) kcal/mol was derived. The sublimation of MoOBr₃ is connected with simultaneous decomposition (see “Inhaltsübersicht”). From the temperature function of the saturated vapor pressure the values ΔH°(subl., MoOBr₃, 298) = 36(±1,5) kcal/mol and ΔS°(subl., MoOBr₃, 298) = 56(±3) cl are calculated.     

The Temperature-Composition Phase Equilibria in the HgTe–HgI2 Pseudobinary System

The temperature-composition phase diagram of the HgTe—HgI₂ pseudobinary system was determined between 25 and 670°C using differential scanning calorimetry, differential thermal analysis, Debye-Scherrer powder X-ray diffraction techniques, and metallographic analysis methods. Solid solutions of HgTe and HgI₂ with the cubic, zinc blende-type structure exist above 300°C, having a maximum solubility of 11.7±0.8 Mol-% HgI₂ in HgTe at 501±5°C. The monoclinic intermediate phase Hg₃Te₂I₂ is formed by a peritectic reaction upon cooling at 501±5°C, with the peritectic point at approximately 37±4 Mol-% HgI₂. The previously unknown cubic phase Hg₃TeI₄ (a = 6.240±0.003 Å) is formed by a eutectoid reaction at 238±3°C and is stable up to 273±3°C, where it melts by a peritectic reaction with the peritectic point at approximately 79±3 Mol-% HgI₂. Between Hg₃TeI₄ and HgI₂ is a eutectic point at 82±3 Mol-% HgI₂ and 250±3°C. The α to β transition of HgI₂ at 133±3°C is independent of sample composition between 33.3 and 100 Mol-% HgI₂.     

Synthese und Struktur der Platin(O)-Verbindungen [(dipb)Pt]2(COD) und (dipb)3Pt2 sowie des clusters Hg6[Pt(dipb)]4 (dipb = (i-Pr)2P(CH2)4P(i-Pr)2)

Synthesis and Structure of the Platinum(0) Compounds [(dipb)Pt]₂(COD) and (dipb)₃Pt₂ and of the Cluster Hg₆[Pt(dipb)]₄ (dipb = (i-Pr)₂P(CH₂)₄P(i-Pr)₂) The reduction of (dipb)PtCl₂ with Na/Hg yields (dipb)Pt as an intermediate which reacts with the amalgam to form the cluster Hg₆[Pt(dipb)]₄ ( 3 ) or decomposes to (dipb)₃Pt₂ ( 2 ) and Pt. In the presence of COD [(dipb)Pt]₂(COD) ( 1 ) is obtained. 1 crystallizes monoclinicly in the space group P2₁/c with a = 1596.1(4), b = 996.5(2), c = 1550.4(3) pm, β = 113.65(2)°, Z = 2. In the dinuclear complex two (dipb)Pt units are bridged by a 1,2-η²-5,6-η² bonded COD ligand. Whereby the C = C double bonds are lengthened to 145 pm. 2 forms triclinic crystals with the space group P1 and a = 1002.0(2), b = 1635.9(3), c = 868.2(2) pm, α = 94.70(2)°, β = 94.45(2)°, σ = 87.95(1)°, Z = 1. In 2 two (dipb)Pt moieties are connected by a μ-dipb ligand in a centrosymmetrical arrangement. 3 is monoclinic with the space group C2/c and a = 1273.8(3), b = 4869.2(6), c = 1660.2(3) pm, β = 95.16(2)°, Z = 4. The clusters Hg₆[Pt(dipb)]₄ have the symmetry C₂. Central unit is a Hg₆ octahedron of which four faces are occupied by Pt(dipb) groups. The bonding in the cluster is discussed on the basis of eight Pt? Hg two center bonds of 267.6 pm and two Pt? Hg? Pt three center bonds with Pt? Hg = 288.0 pm.     

Der erste Polyiodokomplex – Triethylsulfoniumtriiodomercurat(II)-tris(diiod), (Et3S)[Hg2I6]1/2 · 3 I2

The First Polyiodo Complex – Triethylsulfoniumtriiodomercurate(II)-tris(diiodine), (Et₃S)[Hg₂I₆]_1/2 · 3 I₂ After Raman spectroscopic investigation of the system HgI₂/Et₃SI_x, x = 3, 5, 7, triethylsulfoniumtriiodomercuratetris(diiodine), (Et₃S)[Hg₂I₆]_1/2 · 3 I₂ was synthesized by reacting of HgI₂ and liquid Et₃SI₇. The compound crystallizes at room temperature triclinically in the space group P1 with a = 879.4(7), b = 1 209.1(5), c = 1 291.5(5) pm, α = 96.16(3)°, β = 103.82(6)°, γ = 99.05(5)° and Z = 2. The crystal structure is composed of disordered Et₃S⁺ cations, the centrosymmetric complex anion [HgI_2/2I₂]₂^2? and three connecting iodine molecules I₂.     

Zur thermischen Zersetzung und Sublimation des NiI2

Thermical Decomposition and Sublimation of NiI₂ In a membran manometer the thermical decomposition and the sublimation of NiI₂ was measured and in ampuls the sublimation of NiI₂ studied. From the total pressure and the sublimation pressure the enthalpy of formation ΔH°(f,NiI₂,f,298) = ?20 ± 2 kcal/mole and ΔH°(f,NiI₂,g,298) = +31.2 ± 5 kcal/mole was derived. The entropy dates are: S°(NiI₂,f,298) = 35 ± 2 cl, S°(NiI₂,g,298) = 80 ± 1 cl and S°(Ni₂I₄,g,298) = 128 ± 3 cl respectively. The Ni formed with NiI₂ an eutectical system.     

The temperature-composition phase diagram of the HgTe?HgI2 pseudobinary system on the HgTe rich side

The temperature-composition phase diagram of the HgTe? HgI₂ system was determined from 0 to 45 Mol-% HgI₂ between 25 and 670°C using Debye-Scherrer powder X-ray diffraction techniques and differential thermal analysis. Solid solutions of HgTe and HgI₂ with the cubic, zinc blende-type structure exist above 300°C, having a maximum solubility of 11.7 ± 0.8 Mol-% HgI₂ in HgTe at 501 ± 5°C. The known monoclinic compound Hg₃Te₂I₂ is formed by a peritectic reaction upon cooling at 501 ± 5°C, with the peritectic point at approximately 37 ± 4 Mol-% HgI₂.     

The Temperature‐Composition Phase Equilibria in the Hg0.8Cd0.2Te‐HgI2 Pseudobinary System

The temperature‐composition phase equilibria of the Hg_0.8Cd_0.2Te‐HgI₂ system were investigated between about 100 and 800 °C using Debye‐Scherrer powder X‐ray diffraction techniques, differential thermal analysis, differential scanning calorimetry, and thermochemical and structural calculations. This system is a pseudobinary temperature‐ composition plane in the HgTe‐CdTe‐HgI₂ pseudoternary phase diagram. Measurable solid solutions of HgI₂ in Hg_0.8Cd_0.2Te with the cubic zinc blende‐type structure exist between about 290 and 700 °C, with a maximum solubility of 4.9 ± 0.3 mole‐% HgI₂ at 363 ± 3 °C. Further addition of HgI₂ to HgI₂‐saturated Hg_0.8Cd_0.2Te yields the formation of CdI₂, which reduces the mole fraction (x) of CdTe in the Hg_1—xCd_xTe host lattice. After sufficient HgI₂ is added, the host lattice is depleted in CdTe and forms Hg₃Te₂I₂ in addition to CdI₂. Phase fields containing the ternary compound Hg₃TeI₄, which we first observed in the HgTe‐HgI₂ system, also exist in the present system. Quaternary analogs of the known ternary compounds Hg₃Te₂I₂ and Hg₃TeI₄, i.e., Hg_3—yCd_yTe₂I₂ and Hg_3—yCd_yTeI₄, were not observed under present experimental conditions.     

Gesamtdruckmessungen und Gasphasenzusammensetzung über Re2O7, ReO3 und ReO2

Total Pressure Measurements and Gas Phase Composition over Re₂O₇, ReO₃, and ReO₂ The total pressures over Re₂O₇, ReO₃, and ReO₂ have been determined by means of a membrane pressure gauge. The sublimation pressure over Re₂O₇ will be measureable at a temperature above 225°C and amounts 230 Torr at the melting point (at 315°C). The values are . ReO₃ decomposes at a temperature above 400°C according to with ΔH°_r,T = 214.6 ± 2kJ/mol and ΔS°_r,T = 263.2 ± 4J/K · mol. ReO₃ is not detectable in the gaseous phase in measurable quantities. ReO₂ decomposes at a temperature above 800°C according to with ΔH°_r,T = 387,0 ± 8.4 kJ/mol and ΔS°_r,T = 289.1 ± 12.5 J/K · mol.     

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.     

Zur Thermochemie von gasförmigem GeWO4 und GeW2O7

Thermochemistry of Gaseous GeWO₄ and GeW₂O₇ Mass spectrometric investigations with a Knudsen cell arrangement at temperatures between 1258 and 1383 K proved the existence of GeWO₄ and GeW₂O₇ as component of the vaporphase over a mechanical mixture of GeO₂ and WO₂. Using the partial pressures heats of formation (2nd law calculation) and entropies (3rd law calculation) were computed; i. e. GeWO₄: δH°₁₃₃₀ = ?149.8 kcal · mole^?1, S°₁₃₃₀ = 129.9 cal K^?1 mole^?1, GeW₂O₇: δH°_f,₁₃₃₀ = ?310.6 kcal mole^?1, S°₁₃₃₀ = 190.0 cal K^?1 mole^?1. The standard heats of formation and entropies at 298 K, calculated with estimated Cp values are: GeWO₄: δH°_f,₂₉₈ = ?181.6 kcal mole^?1, S°₂₉₈ = 85.0 cal K^?1 mole^?1; GeW₂O₇: δH°_f,₂₉₈ = ?365.8 kcal mole^?1, S°₂₉₈ = 112.1 cal K^?1 mole^?1. The thermochemical data of the GeWO₄ and GeW₂O₇ molecules which also appear at chemical transport experiments [2] with GeO₂ + WO₂, are compared with known gaseous tungstates.     

31P-NMR and X-Ray Studies of the Complexes [HgX2 (1)]. (1=2, 11-bis (diphenylphosphinomethyl)benzo [c]phenanthrene,X=Cl,I)

The ³¹P{¹H}-NMR characteristics of the complexes [HgX₂( 1 )] and [HgX₂-(PPh₂Bz)₂] (X = NO₃, Cl, Br, I, SCN, CN) and the solid state structures of the complexes [HgCl₂( 1 )] and [HgI₂( 1 )] ( 1 = 2,11-bis (diphenylphosphinomethyl)benzo-[c]phenanthrene) have been determined. The ¹J(¹⁹⁹Hg, ³¹P) values increase in the order CN < I < SCN < Br < Cl < NO₃. The two molecular structures show a distorted tetrahedral geometry about mercury. Pertinent bond lengths and bond angles from the X-ray analysis are as follows: Hg? P = 2.485(7) Å and 2.509 (8) Å, Hg? Cl = 2.525 (8) Å and 2.505 (10) Å, P? Hg? P = 125.6(3)°, Cl? Hg? Cl = 97.0(3)° for [HgCl₂( 1 )] and Hg? P = 2.491 (10) Å and 2.500(11) Å, Hg? I = 2.858(5) Å and 2.832(3) Å, P? Hg? P = 146.0(4)°, I? Hg? I = 116.9(1)° for [HgI₂( 1 )]. The equation, derived previously, relating ¹J(¹⁹⁹Hg, ³¹P) and the angles P? Hg? P and X? Hg? X is shown to be valid for 1 .     

Hg2(CH3SO3)2: Synthese,Kristallstruktur, thermisches Verhalten und Schwingungsspektroskopie

Hg₂(CH₃SO₃)₂: Synthesis, Crystal Structure, Thermal Behavior, and Vibrational Spectroscopy Colorless single crystals of Hg₂(CH₃SO₃)₂ are formed in the reaction of HgO, Hg, and HSO₃CH₃. In the monoclinic compound (I2/a, Z = 4, a=883.2(2), b=854.0(2), c=1188.9(2) pm, β = 92.55(2)°, R_all=0.0445) the Hg₂²⁺ ion is coordinated by two monodentate CH₃SO₃^— anions. Further contacts Hg‐O occur in the range from 262 to 276 pm and lead to a linkage of the [Hg₂(CH₃SO₃)₂] units. The thermal analysis shows that Hg₂(CH₃SO₃)₂ decomposes at 300° yielding elemental mercury. The mass numbers of the species evolved lead to the assumtion that SO₃, SO₂, CO₂, CO and H₂CO are formed during the reaction. In the IR and the Raman spectrum the typical vibrations of the CH₃SO₃^— ion are observed, the Raman spectrum shows the Hg‐Hg stretching vibration at 177 cm^—1 within the Hg₂²⁺ ion additionally.     

Untersuchungen zum Zustandsbarogramm und Schmelzdiagramm der Systeme BiI3?HgI2 und BiI3?I2

Investigations on the Barogram and Melting Diagram of the Systems BiI₃? HgI₂ and BiI₃? I₂ The barograms of the systems BiI₃? HgI₂ and BiI₃? I₂ are determined by total pressure measurements in a membrane manometer. The melting diagrams follow from DTA measurements and the barogram. Both systems are eutectic with eutectica at 1.5 mol% BiI₃ and 110°C for BiI₃? I₂ and 9 mol% BiI₃ and 243°C for BiI₃? HgI₂.     

Polysulfonylamine. XXXVII. Darstellung von Quecksilberdimesylamiden. Kristall- und Molekülstrukturen von Hg[N(SO2CH3)2]2, Hg[{N(SO2CH3)2}2(DMSO)2] und Hg[{N(SO2CH3)2}2(HMPA)]

Polysulfonyl Amines. XXXVII. Preparation of Mercury Dimesylamides. Crystal and Molecular Structures of Hg[N(SO₂CH₃)₂]₂, Hg[{N(SO₂CH₃)₂}₂(DMSO)₂], and Hg[{N(SO₂CH₃)₂}₂(HMPA)] Hg[N(SO₂CH₃)₂]₂ ( 1 ) and Hg₂[N(SO₂CH₃)₂]₂ ( 2 a ) are formed as colourless, sparingly soluble precipitates when solutions of Hg(NO₃)₂ or Hg₂(NO₃)₂ in dilute nitric acid are added to an aqueous HN(SO₂CH₃)₂ solution. By a similar reaction, Hg₂[N(SO₂C₆H₄ ? Cl? 4)₂]₂ is obtained. 1 forms isolable complexes of composition Hg[N(SO₂CH₃)₂]₂ · 2 L with L = dimethyl sulfoxide (complex 3 a ), acetonitrile, dimethyl formamide, pyridine or 1,10-phenanthroline and a (1/1) complex Hg[N(SO₂CH₃)₂]₂ · HMPA ( 4 ) with hexamethyl phosphoramide. Attempted complexation of 2 a with some of these ligands induced formation of Hg⁰ and the corresponding Hg^II complexes. Crystallographic data (at -95°C) are for 1: space group 14₁/a, a = 990.7(2), c = 2897.7(8) pm, V = 2.844 nm³, Z = 8, D_x = 2.545Mgm^?3; for 4a: space group P1 , a = 767.8(2), b = 859.2(2), c = 925.2(2)pm α = 68.44(2), β = 86.68(2), γ = 76.24(2)°, V = 0.551nm³, Z = 1, D_x = 2.113 Mgm^?3; for 4: space group P2₁/c, a = 1041.3(3), b = 1545.4(3), c = 1542.5(3) pm, β = 100.30(2)°, V = 2.474nm³, Z = 4, D_x = 1.944Mgm³. The three compounds form molecular crystals. The molecular structures contain a linear or approximately linear, covalent NHgN moiety; the Hg? N distances and N? Hg? N angles are 206.7(4) pm and 176.3(2)° for 1, 207.2(2) pm and 180.0° for 3a, 205.7(4)/206.7(4) pm and 170.5(1)° for 4. In the complexes 3a and 4, the 0-ligands are bonded to the Hg atoms perpendicularly to the N? Hg? N axes, leading in 3a to a square-planar trans-(N₂O₂) coordination with Hg? 0 261.2(2) pm and N? Hg? O 92.3(1)/87.7(1)°, in 4 to a slightly distorted T-shaped (N₂O) geometry with Hg? 0 246.2(4)pm and N? Hg? 0 96.7(1)/92.0(1)°. In all three structures, the primary coordination is extended to a severely distorted (N₂O₄) hexacoordination by the appropriate number of secondary, inter- and/or intramolecular Hg…?0 inter-actions (0 atoms from sulfonyl groups, Hg…?O distances in the range 280—300pm). The intramolecular Hg…?O interactions give rise to nearly planar four-membered [HgNSO] rings. The molecule of 1 has a two-fold axis through the bisector of the N? Hg? N angle, the molecule of 3a an inversion center at the Hg atom. The molecule of 4 has no symmetry.     

Sättigungsdrucke,Bildungsenthalpien von WOBr4 und WO2Br2, die Reaktionsgleichgewichte 2WO2Br2 = WO3 + WOBr4 und 2WOBr4 + SiO2 = 2WO2Br2 + SiBr4

The saturation vapour pressures of WOBr₄ and WO₂Br₂ and their reaction equilibria have been determined by means of a membrane zero manometer and ampoule quenching experiments, respectively. From the pressuretemperature dependence the following sublimation data were estimated: Δ H° (subl., WOBr₄, 298) = 29.4 (± 1.0) kcal/mole; Δ H° (subl., WO₂Br₂, 298) = 36.6 (±1.5) kcal/mole; Δ S° (subl., WOBr₄, 298) = 50.1 (± 1) cl; Δ S° (subl. WO₂Br₂, 298) = 53.0 (±1.5) cl. For the decomposition reaction of solid WO₂Br₂ were obtained: Δ H° (s, 690) 37.5 (± 0.7) kcal/mole, Δ S° (s, 690) = 49.0 (± 0.5) cl; and for the decomposition of gaseous WO₂Br₂: Δ H° (g, 690) = ?29.6 (± 2.0) kcal/mole, Δ S°. (g, 690) = ?44.5 (± 1.5) cl.     

Refinement of the Crystal Structure of Sr3Hg2

Mixtures of strontium and mercury in molar ratios of 7:3 have been annealed for 20 days at 520°C. From the pure product Sr₃Hg₂ single crystals have been obtained. Sr₃Hg₂ crystallizes in the U₃Si₂ type of structure (space group P4/mbm); the cell constants are a = 8.883 (2) Å and c = 4.553(1) Å. All of the Hg atoms are involved in Hg₂ dumbbells with Hg? Hg distances of 3.41 Å.