Influence of xenon difluoride on the optical properties of fluorozirconate and fluorohafnate glasses

To study the effect of xenon difluoride as a fluorinating agent on optical properties of glasses in ZBLAN (ZrF₄–BaF₂–LaF₃–AlF₃–NaF) and HBLAN (HfF₄–BaF₂–LaF₃–AlF₃–NaF) systems, their optical transmission in the range from UV to IR was investigated. The treatment of the initial fluorides with XeF₂ was shown to lead to a broadening of the transmission region of the obtained glasses both in the UV and IR ranges. Moreover, the treatment of the batch with xenon difluoride leads to the removal of oxygen-containing impurities that absorb in the region of 2.8 μm.     

Non-isothermal crystallization kinetics of V2O5-MoO3-Bi2O3 glasses

Characteristic temperatures, such as T _g (glass transition), T _x (crystallization temperature) and T _l (liquidus temperature) of glasses from the V₂O₅-MoO₃-Bi₂O₃ system were determined by means of differential thermal analysis (DTA). The higher content of MoO₃ improved the thermal stability of the glasses as well as the glass forming ability. The non-isothermal crystallization was investigated and following energies of the crystal growth were obtained: glass #1 (80V₂O₅·20Bi₂O₃) E _G=280 kJ mol^-1, glass #2 (40V₂O₅·30MoO₃·30Bi₂O₃) E _G=422 kJ mol^-1 and glass #3 (80MoO₃·10V₂O₅·10Bi₂O₃) E _G=305 kJ mol^-1. The crystallization mechanism of glass #1 (n=3) is bulk, of glass #3 (n=1) is surface. Bulk and surface crystallization was supposed in glass #2. The presence of high content of a vanadium oxide acts as a nucleation agent and facilitates bulk crystallization. This revised version was published online in August 2006 with corrections to the Cover Date.     

2‐Amino‐5‐nitro‐4,6‐dipiperidinopyrimidinium hydrogen­sulfate monohydrate: hydrogen‐bonded sheets containing highly distorted cations

In the title compound, C₁₄H₂₃N₆O₂⁺·HSO₄⁻·H₂O, the pyrimidinium ring of the cation adopts a twist‐boat conformation, induced by steric clashes between adjacent ring substituents; the anions and the water mol­ecules are linked by three O—H⃛O hydrogen bonds [H⃛O = 1.70–1.78 Å, O⃛O = 2.548 (2)–2.761 (2) Å and O—H⃛O = 161–168°] into chains of edge‐fused R(12) rings, which are linked into sheets by the cations, via three N—H⃛O hydrogen bonds [H⃛O = 1.96–2.17 Å, N⃛O = 2.820 (2)–2.935 (2) Å and N—H⃛O = 145–173°].     

Die Kristallstruktur von Lithiummesitolat [{LiOC6H2-2,4,6-(CH3)3}4(THF)3]

X-Ray Structure of [{LiOC₆H₂-2,4,6-(CH₃)₃}₄(THF)₃] The title compound crystallized from a THF/OEt₂ solution. Its crystal structure (monoclinic, P2₁/c, a = 21.362(3), b = 13.441(2), c = 17.188(2) Å, β = 98.39(1)°, Z = 4, R = 0,0911, wR² = 0,2562) is built up by cuban-like tetrameric units. Three of the four Li cations attain a coordination number of four by binding to an additional THF molecule. Li(4) without THF coordination has a short distance to one ortho-methyl group (Li(4)…C(27) 2.669(10) Å). The Li–O_ph bonding distances vary from 1.869(10) to 2.051(10) Å (average 1.97 Å); the average bonding distance for Li–O_THF is 2.012(10) Å. Averaged bonding angles for Li–O_ph–Li′ and O_ph–Li–O′_ph amount to 84.4(4)° and 95.4(4)°, respectively. The Li…Li distances significantly differ from each other. They range from 2.556(12) to 2.739(11) Å (average 2.65(1) Å).     

Phase Equilibria in the System CuO‐NiO‐P4O10 and Synthesis,Crystal Structure,and Characterization of the New Copper Nickel Oxide Phosphate Cu3NiO(PO4)2

The system CuO‐NiO‐P₄O₁₀ was investigated using a solid state reaction between CuO, NiO, and (NH₄)₂HPO₄ in quartz crucibles at 900 °C. The powder samples were characterized by X‐ray diffraction, TG/DTA, electrochemical measurements, IR, and UV/Vis spectroscopy. Single crystals of a new quaternary phase Cu₃NiO(PO₄)₂ were achieved by cooling the melted compound in a sealed, evacuated quartz ampoule. Cu₃NiO(PO₄)₂ crystallizes in the monoclinic space group P2₁/n (no 14) with a = 8.2288(2) Å, b = 9.8773(2) Å, c = 8.2777(3) Å, β = 107.82(2)°, Z = 4. The three‐dimensional framework consists of distorted tetragonal pyramides [Cu1O₅], distorted planar squares [Cu2O₄], octahedra [Cu3O₆], and [NiO₆] and [PO₄] tetrahedra. The TG‐DTA of the new phase showed an incongruent melting at 1055 °C. The open circuit voltage of this material was measured to determine the electrochemical properties. The measurement revealed an initial capacity of 236 Ah · g^–1 and a voltage plateau at 2.05 V. Furthermore, it was possible to identify the phase equilibria and to obtain the phase diagram at 900 °C.     

The Crystal Structure of Tl2Te3 – a Reinvestigation

Crystals of the title compound were obtained by annealing a powder of Tl₂Te₃ in a vertical temperature gradient (230 °C–240 °C, 4 weeks). Tl₂Te₃ crystallizes in space group C2/c with lattice parameters of a = 13.275(1) Å, b = 6.562(1) Å, c = 7.918(1) Å, and β = 107.14°(2). The tellurium atoms form chains [Te₃^2–], consisting of interconnected linear triatomic · Te–^Te–Te · groups which are isosteric with XeF₂. The Te–Te distances of the XeF₂-like units are 3.02 Å, the connecting ones 2.83 Å.     

Nb2Se2I6: Eine neue Strukturvariante bei Niobchalkogenidhalogeniden mit Kettenstruktur

Nb₂Se₂I₆: A New Structural Variation of Niobium Chalcogenide Halides with Chain Structure Single crystals of Nb₂Se₂I₆, exhibiting a metallic lustre, (monoclinic, C2/c; a = 7.110(1), b = 13.899(3), c = 13.688(3) Å, β = 99.58(3)°; Z = 8) have been obtained by heating mixture of the elements (molar ratio Nb : Se : I = 3 : 1 : 7) in evacuated sealed fused silica tubes at 1073 K for two weeks. After rapid quenching, the tube was reheated to 773 K and then cooled at a rate of 2 K h^–1. Crystals of the title compound formed at the colder part of the tube besides higher niobium iodides. Nb₂Se₂I₆ can also be obtained by slow cooling of a stoichiometric mixture of the elements from 1073 K as a minor product besides triclinic NbSe₂I₂ [1]. The crystal structure is built up with one-dimensional infinite chains [Nb₂Se₂I₄I_4/2]. The main structural features are a short Nb–Nb distance (2.903(1) Å) and a short Se–Se distance (2.318(2) Å) which is expected for +4 and –1 oxidation states, respectively. Homeotypic phases with Nb₂Y₂X₆ chains (Y = Se, Te; X = Br, I) are known [2] except for the combination Y = Se, X = I. They show a primitive rod packing of the Nb₂Y₂X₆ chains in contrast to the title compound which shows a centered rod packing.     

Synthesis and crystal structure of 10a‐oxo‐1‐phenylimino‐ 10‐propyl‐3,4,10,10a‐tetrahydro‐1H‐ 2‐thia‐4a,10‐diaza‐10aλ5‐ phospha‐phenanthren‐9‐one

The title novel fused tricyclic phosphoroheterocycle, C₁₉H₂₀N₃O₂PS, was synthesized in an excellent yield of 88.5% via the reac‐ tion of 1‐(2‐bromoethyl)‐2,3‐dihydro‐3‐propyl‐1,3,2‐benzodiazaphosphorin‐4(1H)‐one 2‐oxide with phenyl isothiocyanate, which contains the proximate imino and phosphoryl groups in the fused heterocycle. The crystallographic data analysis reveals that the title compound crystallizes into triclinic space group P with unit cell parameters: a = 9.159(3) Å, b = 10.463(4) Å, c = 10.698(4) Å, α = 88.090(6)°, β = 86.921(6)°, γ = 70.528(6)°, V = 965.0(6) ų for Z = 2 and there is a fused three‐ring in the molecule. The structure has been solved by direct methods and refined to R = 0.0424 for 2451 observed reflections with I >2 σ(I). The proximate imino and phosphoryl groups are not coplanar because both are jointly located in the fused heterocycle, thus having ring tension and this then destroys the conjugation between the CN and the PO moieties. © 2005 Wiley Periodicals, Inc. Heteroatom Chem 16:671–676, 2005; Published online in Wiley InterScience ( www.interscience.wiley.com ). DOI 10.1002/hc.20169     

XPS Study of the Corrosion Protection of Fluorozirconate Glasses Dip-Coated with SnO2 Transparent Thin Films

Tin oxide nanoparticles prepared by an aqueous sol–gel method were deposited by dip-coating on fluorozirconate glass, ZBLAN (53%ZrF₄-20%BaF₂-4%LaF₃-3%AlF₃-20%NaF) to improve its resistance against wet corrosion. The aqueous leaching of uncoated and SnO₂-coated fluorozirconate glass was studied by X-ray photoemission spectroscopy (XPS) and it was shown that even an ultra thin tin dioxide film provides good protection of the glass surface against the bulk propagation of the hydrolytic attack.     

New preparation method of chlorotriphenylantimony aryloxides Ph3SbCl(OAr)

The reaction of bis(2,6-dichlorophenoxo)triphenylantimony with triphenylantimony dichloride gave chloro(2,6-dichlorophenoxo)triphenylantimony Ph₃SbCl(OC₆H₃Cl₂-2,6) (I). 2,6-Dichlorophenoxotetraphenylantimony Ph₄Sb(OC₆H₃Cl₂-2,6) (II) was prepared from pentaphenylantimony and bis(2,6- dichlorophenoxo)triphenylantimony. According to X-ray diffraction data, the antimony atoms in I and II have a distorted trigonal-bipyramidal coordination with the following axial: OSbCl, 179.59(5)° (I); CSbO, 178.20(14)° (II); the equatorial angles are 115.72(9)°–124.87(10)° (I) and 111.43(18)°–123.18(19)° (II); the equatorial bond lengths are Sb–C, 2.099(3)–2.111(2) Å (I), 2.111(4)–2.122(5) Å (II); and the axial bond lengths are Sb–Cl, 2.4740(7) Å; Sb–O, 2.0802(16) Å (I); Sb–O, 2.237(3) Å; and Sb–C, 2.167(4) Å (II) (CIF files CCDC no. 998625 for I and no. 1010553 for II).     

Adducts of 1,1,1‐tris(4‐hydroxyphenyl)ethane with diamines: three‐dimensional hydrogen‐bonded frameworks formed with 1,6‐diaminohexane and 2,2′‐bipyridyl

The adduct 1,6‐di­amino­hexane–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2) is a salt {hexane‐1,6‐diyldiammonium–4‐[1,1‐bis(4‐hydroxyphenyl)ethyl]phenolate (1/2)}, C₆H₁₈N₂²⁺·2C₂₀H₁₇O₃^?, in which the cation lies across a centre of inversion in space group P. The anions are linked by two short O—H?O hydrogen bonds [H?O 1.74 and 1.76 Å, O?O 2.5702 (12) and 2.5855 (12) Å, and O—H?O 168 and 169°] into a chain containing two types of R(24) ring. Each cation is linked to four different anion chains by three N—H?O hydrogen bonds [H?O 1.76–2.06 Å, N?O 2.6749 (14)–2.9159 (14) Å and N—H?O 156–172°]. In the adduct 2,2′‐bipyridyl–1,1,1‐tris(4‐hydroxy­phenyl)­ethane (1/2), C₁₀H₈N₂·2C₂₀H₁₈O₃, the neutral di­amine lies across a centre of inversion in space group P2₁/n. The tris­(phenol) mol­ecules are linked by two O—H?O hydrogen bonds [H?O both 1.90 Å, O?O 2.7303 (14) and 2.7415 (15) Å, and O—H?O 173 and 176°] into sheets built from R(38) rings. Pairs of tris­(phenol) sheets are linked via the di­amine by means of a single O—H?N hydrogen bond [H?N 1.97 Å, O?N 2.7833 (16) Å and O—H?N 163°].     

Präparative und röntgenographische Untersuchungen über das System Al2S3?ZnS (Temperaturbereich 800–1080°C)

Einkristalle von α-ZnAl₂S₄ mit Spinellstruktur (a = 10,009₃ Å) lassen sich durch chemische Transportreaktion bei 740°C erhalten. Beim Erhitzen der Verbindung auf 800–900°C tritt Zerfall in eine ZnS-arme defekte Spinellphase und in eine ZnS-reiche Phase mit defekter Wurtzitstruktur ein. Bei 830–860°C liegen die Grenzen des zweiphasigen Bereichs etwa bei Zn_0,98Al_2,01S₄ (kubische α-Phase, a = 10,007₂ Å (25°C)) und Zn_1,80Al_1,47S₄ (hexagonale Wurtzitphase, a = 3,76₀, c = 6,1₅ Å (25°C)). Mischungen von ZnS, Al und S entsprechend der Zusammensetzung Zn_xAl_8/3?2x/3S₄ mit 0,33 ≤ x ≤ 0,98, die auf 830–860°C (70–140 h) erhitzt worden sind, liefern nach Abkühlung auf Raumtemperatur homogene Produkte mit defekter Spinellstruktur. Die bei der Zusammensetzung Al₂S₃ · ZnS beobachtete Mischungslücke setzt sich bei höherer Temperatur unter Verschiebung der Phasengrenzen und Ausbildung von Hochtemperatur-Phasen fort. Eine Hochtemperaturmodifikation des ZnAl₂S₄ existiert bis 1080°C nicht. Mischungen von ZnS, Al und S mit 0,44 ≤ x ≤ 0,85, die auf 1060–1080°C (72–96 h) erhitzt worden sind, zeigen nach Abkühlung auf Raumtemperatur eine bisher nicht beschriebene rhomboedrische Hochtemperaturphase (γ-Phase), deren Struktur als eine Defektstruktur des ZnIn₂S₄-Typs aufgefaßt werden kann. Bei x = 1,00 erhält man nach thermischer Behandlung bei 1060–1080°C ein zweiphasiges Produkt, das neben der γ-Phase eine orthorhombische Phase (β-Phase, Überstruktur des Wurtzit-Typs) enthält. Die β-Phase tritt als einzige Phase auf, wenn für die Ausgangsmischung gilt: 1,40 ≤ x ≤ 1,70. Die Löslichkeit von Al₂S₃ in ZnS (Wurtzit) unter Bildung einer statistischen Defektstruktur des Wurtzit-Typs reicht bei 1060–1080°C bis Zn_1,70?1,80Al_1,53?1,47S₄(Al₂S₃ · (2,2-2,5) ZnS). Preparative and X-Ray Investigations on the System Al₂S₃? ZnS (Temperature Region 800–1080°C) Single crystals of α-ZnAl₂S₄ with spinel structure (a = 10.009₃ Å) have been obtained by chemical transport reaction at 740°C. Heating of the compound to 800–900°C leads to decomposition and formation of a ZnSαpoor defect spinel phase and a ZnS-rich phase with a defect wurtzite structure. The boundaries of the two-phase region at 830–860°C are approximately Zn_0,98Al_2.01S₄ (cubic α-phase, a α 10.007₂ Å (25°C)) and Zn_1.80Al_1.47S₄ (hexagonal wurtzite-phase, a = 3.76₀, c = 6.1₅ Å (25°C)). Mixtures of ZnS, Al and S with the composition Zn_xAl_8/3?2x/3S₄ and 0.33 ≤ x ≤ 0.98, which are heat treated at 830–860°C (70–140 h), yield after cooling to room temperature homogeneous products with a defect spinel structure. The miscibility gap at the composition Al₂S₃ · ZnS continues at higher temperatures with a shift of the phase boundaries and formation of high-temperature phases. A high-temperature modification of ZnAl₂S₄ does not exist up to 1080°C. When mixtures of ZnS, Al and S with 0.44 ≤ x ≤ 0.85 are heat treated at 1060–1080°C(72-96 h), a rhombohedra1 high-temperature phase (γ-phase) is obtained after cooling to room temperature, which has not previously been observed. I t s structure can be described as a defect structure of the ZnIn, S, type. With x = 1.00, after thermal treatment a t 1060-1080°C, a two-phase product is obtained, containing γ-phase in addition to an orthorhombic phase (β-phase, super-lattice of the wnrtzite type). The β-phase is the only phase occuring in products with 1.40 ≤ x ≤ 1.70. The solubility of Al, S, in ZnS (wurtzite) at 1060-1080°C with formation of a defect wurtzite structure, in which the cations are disordered, reaches as far as Zn_l.70?1.80Al_l.53?1.47S₄[Al₂S₃·(2.2-2.5)ZnS].     

Synthesis,Crystal Structure and Characterization of the Copper Iron Phosphate Cu8Fe2O5(PO4)4

The system CuO‐Fe₂O₃‐P₂O₅ has been investigated by means of the solid state reaction between CuO, Fe₂O₃ and (NH₄)₂HPO₄ in quartz crucibles at 900 °C. The powder samples were characterized by X‐ray diffraction, IR spectroscopy and TG/DTA. Single crystals of a new quaternary phase Cu₈Fe₂P₄O₂₁ were achieved by cooling from the melt of the compound in a sealed, evacuated quartz ampoule. Cu₈Fe₂O₅(PO₄)₄ crystallizes in the monoclinic space group C2/m (No 12) with a = 15.9733(8) Å, b = 5.9438(3) Å, c = 9.5530(5) Å, β = 113.76(1)°, Z = 2. The three‐dimensional framework consists of [FeO₆] octahedra, three different [CuO₅] polyhedra and [PO₄] tetrahedra. Cu₈Fe₂P₄O₂₁ exhibits an incongruently melting point at 945 °C.     

Polymeric (μ2‐nitrato‐κ2O:O′)(μ2‐nitrato‐κ2O:O)(μ4‐pyridinium‐4‐thiol­ato‐κ4S:S:S:S)­disilver(I)

The title compound, [Ag₂(NO₃)₂(C₅H₅NS)]_n, was obtained from the reaction of silver nitrate with bis(4‐pyridyl) disufide (4‐PDS) in a mixture of ethanol and water, which suggests that the di­sulfide bond of 4‐PDS can be cleaved under mild conditions. The structure of the title compound is a two‐dimensional infinite array in which the asymmetric unit contains two Ag atoms, a pyridinium‐4‐thiol­ate mol­ecule and two nitrate groups. Each pyridinium‐4‐thiol­ate mol­ecule acts as a μ₄ bridge, linking four Ag atoms, with Ag—S bond distances of 2.4870 (19), 2.5791 (19), 2.5992 (19) and 2.848 (2) Å. The Ag⋯Ag distances lie in the range 2.889 (2)–3.049 (1) Å.     

Synthesis and molecular structure of catena((μ<Subscript>2</Subscript>-4,4,10,10-tetramethyl-1,3,7,9-tetraazaspiro[5.5]undecane-2,8-dione-<Emphasis Type="Italic">O,O'</Emphasis>)- aquadinitratocadmium(II))

A coordination polymer, catena((μ₂-4,4,10,10-tetramethyl-1,3,7,9-tetraazaspiro[5.5]undecane- 2,8-dione-O,O')-aquadinitratocadmium(II) {[Cd(C₁₁H₂₀N₄O₂)(H₂O)(NO₃)₂]} _n } (I), has been prepared for the first time from cadmium(II) nitrate and the bicyclic bisurea 4,4,10,10-tetramethyl-1,3,7,9-tetraazaspiro[5.5]undecane-2,8-dione (TTSU). Its molecular structure has been determined (CIF file CCDC no. 903387). Triclinic crystals: space group P1?, a = 8.9967(4) Å, b = 9.6011(4) Å, c = 12.5131(7) Å, α = 76.307(4)°, β = 73.465(5)°, γ = 63.310(5)°, V = 918.26(8) ų, ρ_calc = 1.789 g/cm³, Z = 2. The Rietveld refinement was carried out at 293 K to confirm the single-phase constitution of the obtained powder sample of I: a = 8.9972(4) Å, b = 9.6104(4) Å, c = 12.5203(4) Å, α = 76.373(3)°, β = 73.485(3)°, γ = 73.485(3)°, V = 919.80(6) ų. A number of lines not corresponding to the main phase and not identified from PDF-2 database are observed on the powder X-ray diffraction pattern. The Rietveld refinement showed that the sample contains 91.4 wt % of the main compound I and 8.6 wt % of the TTSU nitrate admixture. The cadmium atom is coordinated by the O(1) and O(1)ⁱ atoms of two molecules of the organic ligand (L) generated by the symmetry operation (ⁱ1–x,–y,–z), the O(2)ⁱⁱ atom of the third ligand L molecule bound with the supporting one with the symmetry operation (ⁱⁱ–x,–y,–z), a water molecule, and a bidentate and a monodentate nitrate anions. The coordination number of the cadmium atom is 7, the coordination polyhedron is a distorted pentagonal bipyramid. The Cd···Cd distance is 4.0208 (3) Å.     

Synthese,Struktur und Reaktionen von Vanadiumsäureestern VO(OR)3: Umesterung und Reaktion mit Oxalsäure

Synthesis, Structure, and Reactions of Vanadium Acid Esters VO(OR)₃: Transesterification and Reaction with Oxalic Acid The reaction of tert.‐Butyl Vanadate VO(O‐tert.Bu)₃ ( 1 ) with H₂C₂O₄ in the primary alcohols ethanol and propanol results in the formation of (ROH)(RO)₂OV^V(C₂O₄)V^VO(OR)₂(HOR) (with R = C₂H₅ 2 and R = C₃H₇ 3 ). Compounds 2 and 3 are the first structurally characterized neutral, binuclear oxo‐oxalato‐complexes with pentavalent vanadium. The two vanadium atoms are connected by a bisbidentate oxalate group. The {VO₆} coordination at each vanadium site is completed by a terminal oxo group, an alcohol ligand and two alcoxide groups. The binuclear molecules are connected to chains by hydrogen bonding. In the case of 2 a reversible isomorphic phase transition in the temperature range of –90 °C to –130 °C is observed. From methanolic solution the polymeric Methyl Vanadate [VO(OMe)₃] ( 4 ) was obtained by transesterification. A report on the crystal structures of 1 , 2 and 3 as well as a redetermination of the structure of 4 is given. Crystal data: 1, orthorhombic, Cmc2₁, a = 16.61(2) Å, b = 9.274(6) Å, c = 10.784(7) Å, V = 1662(2) ų, Z = 4, d_c = 1.144 gcm^–1; 2 (–90 ° C) , monoclinic, I2/a, a = 33.502(4) Å, b = 7.193(1) Å, c = 15.903(2) Å und β = 143.060(3)°, V = 2303(1) ų, Z = 4, d_c = 1.425 gcm^–1; 2 (–130 ° C) , monoclinic, I2/a, a = 33.274(4) Å, b = 7.161(1) Å, c = 47.554(5) Å, β = 142.798(2)°, V = 6851(1) ų, Z = 12, d_c = 1.438 gcm^–1; 3 , triklinic, P1, a = 9.017(5) Å, b = 9.754(5) Å, c = 16.359(9) Å, α = 94.87(2)°, β = 93.34(2)°, γ = 90.42(2)°, V = 1431(1) ų, Z = 2, d_c = 1.340 gcm^–1; 4 , triklinic, P1, a = 8.443(2) Å, b = 8.545(2) Å, c = 9.665(2) Å, α = 103.202(5)°, β = 96.476(5)°, γ = 112.730(4)°, V = 610.2(2)ų, Z = 4, d_c = 1.742 gcm^–1.     

Synthesis and Crystal Structure of Copper(II) Trifluoroacetates,Cu2(CF3COO)4 · 2 CH3CN and Cu(CF3COO)2(H2O)4

Cu₂(CF₃COO)₄ · 2 CH₃CN ( I ) and Cu(CF₃COO)₂(H₂O)₄ ( II ) have been prepared by concentrating of acetonitrile and aqueous solutions respectively. According to X-ray data, the complex I consists of binuclear molecules with Cu–O 1.969 Å, Cu–N 2.114 Å. The Cu…Cu distance was found to be 2.766 Å, one of the longest for dimeric structures, apparently, due to the high acidity of trifluoroacetic acid. The coordination environment of Cu atom in II can be described as 4 + 2: 2 Cu–O (H₂O) 1.937 Å, 2 Cu–O (CF₃COO) 1.985 Å, 2 Cu–O (H₂O) 2.447 Å. The mononuclear structure is stabilized by formation of two intra- and six intermolecular hydrogen bonds.     

Halogenomercurate: Darstellung und Strukturen von [Cu(en)2][Hg2Cl6], [Cu(en)2][Hg2Br6] und [Cu(en)2][HgBr4]

Halomercurates: Syntheses and Crystal Structures of [Cu(en)₂][Hg₂Cl₆], [Cu(en)₂][Hg₂Br₆], and [Cu(en)₂][HgBr₄] Crystals of [Cu(en)₂][Hg₂Cl₆] ( 1 ) have been obtained by layering a solution of Hg(NO₃)₂ and NaCl with a solution of [Cu(en)₂]SO₄. An analogous procedure, using NaBr instead of NaCl, gave crystals of [Cu(en)₂][HgBr₄] ( 3 ). Crystals of [Cu(en)₂][Hg₂Br₆] ( 2 ) were obtained by gel crystallization using the same starting materials as for 3 . The complexes show very low solubility. The dinuclear anions of 1 consist of two nearly planar HgCl₃ units related by a center of symmetry. In 2 infinite anionic chains are present, made up of parallel HgBr₃ units. These units are packed in such a way as to produce a trigonal bipyramidal configuration around the Hg atoms. 3 contains mononuclear deformed tetrahedral [HgBr₄]^2– anions. In all three complexes the packing of the ions is such that halogen atoms of halomercurate anions complete a tetragonal bipyramidal coordination at Cu. The resulting Cu–Halogen distances are 2.924 Å for 1 , 3.036 Å for 2 and 3.085 and 3.119 Å for 3 . 1 : Space group P 1, Z = 1, lattice constants at 20 °C: a = 7.000(2), b = 7.526(2), c = 8.239(2) Å; α = 88.39(2), β = 86.06(2), γ = 86.10(3)°; R₁ = 0.040. 2 : Space group P2₁/c, Z = 2, lattice constants at –50 °C: a = 7.185(1), b = 16.338(2), c = 7.814(1) Å; β = 94.88(2)°; R₁ = 0.033. 3 : Space group P2₁/n, Z = 4, lattice constants at 20 °C: a = 8.055(3), b = 13.101(3), c = 13.814(3) Å; β = 91.24(3)°; R₁ = 0.092.     

Synthesis,Structure, and Stability of Cs4ZrO4

The colorless Cs₄ZrO₄ is obtained from the reaction of stoichiometric proportions of Cs, CsO₂, and finely divided ZrO₂ in a sealed Ag container at 400–650°C for several days. Regrinding and re-reaction provide a single phase sample. The compound is monoclinic (P2₁/c, Z = 4, a = 7.172 (1) Å, b = 19.907 (1) Å, c = 7.157 (1) Å, β = 113.1 (1)Å, R = 0.032) and isostructural with Cs₄PbO₄, with isolated ZrO₄^4? tetrahedra (d(Zr–O) = 1.97 Å). The compound decomposes to Cs₂ZrO₃ (a) in the presence of excess oxygen or CsO₂, (b) in high vacuum near 275°C, or (c) in a sealed container at about 730 ± 10°C.     

New Examples for the Unexpected Stability of the 10π‐Electron Hückel Arene [Si6]10–

The compounds Ba₄Ag₂Si₆, Eu₄Ag₂Si₆, and Ca₄Ag₂Si₆, prepared from the elements at 1273 K (the components in inner corundum crucibles are enclosed in sealed quartz ampoules), are brittle semiconductors with silvery luster. They react slowly with acids liberating hydrogen. Ba₄Ag₂[Si₆] and Eu₄Ag₂[Si₆] crystallize like Ba₄Li₂[Si₆] (space group Fddd (No. 70); a = 8.613 Å, b = 14.927 Å, c = 19.639 Å, and a = 8.420 Å, b = 14.585 Å, c = 17.864 Å, respectively), whereas Ca₄Ag₂[Si₆] represents a new structure type (space group Fmmm (No. 69); a = 8.315 Å, b = 14.391 Å, c = 8.646 Å). The three compounds are Zintl phases with the formal charges M²⁺, Ag⁺ and [Si₆]^10–. The mean bond lengths d(Si–Si) = 2.335–2.381 Å in the 10π‐Hückel arene [Si₆]^10– as well as d(Ag–Si) = 2.464–2.595 Å vary with the size of the M²⁺ cations. The chemical bonding was analyzed in terms of the Electron Localization Function (ELF) and compared with the bonding in related systems (Ce₄Co₂Si₆).