Synthese,Eigenschaften und Kristallstrukturen von Magnesium-Diazadien-Komplexen

Synthesis, Properties and Crystal Structures of Magnesium Diazadiene Complexes Reactions of phenyl-substituted 1,4-diaza-1,3-butadienes (DAD) RN?CPh? CPh?NR (R = C₆H₅) 1a , C₆H₄-4-CH₃ 1b , C₆H₄-4-OCH₃ ( 1c ) with magnesium in dimethoxyethan lead to complexes of the type [Mg(DAD)₂(DME)] 2a–c , with DAD ligands in form of radical anions. Furthermore, highly reactiv complexes of the composition [Mg(DAD)(DME)₂] 3a–c could be obtained. The crystal structures of 2a, 3a and 3c were determined.     

Synthese und Kristallstrukturen von IMalnBr4 und NaInI4

Inhaltsübersicht. Einkristalle von NaInBr₄ und NaInI₄ erhält man aus Gemengen der binären Komponenten durch langsames Abkühlen der Schmelze. NaInBr₄ gehört zum NaAlCl₄-Typ: Orthorhombisch, P2₁2₁2₁, Z = 4; a = 1108,1(1); b = 1050,7(1); c = 676,1(1) pm. NaInI₄ ist isotyp mit LiAlCl₄: Monoklin, P2₁/c, Z = 4; a = 852,1(2); b = 766,1(2); c = 1558,3(3) pm; β = 92,65(2)°. In beiden Strukturen treten annähernd tetraedrische Baugruppen [InX₄]^– (X = Br, I) auf. Die Koordinationszahl von Na⁺ ist C.N. = 6 (NaInI₄; leicht verzerrt oktaedrisch) bzw. C.N. = 6+1+1 (NaInBr₄; verzerrtes, doppelt bekapptes Prisma). Synthesis and Crystal Structures of NaInBr₄ and NaInI₄ Single crystals of NaInBr₄ and NaInI₄ are obtained from mixtures of the binary components by slow cooling of the melts. NaInBr₄ belongs to the NaAlCl₄ type of structure: Ortho-rhombic, P2₁2₁2₁, Z = 4, a = 1108.1(1), b = 1050.7(1), c = 676.1(1) pm. NaInI₄ is isotypic with LiAlCl₄: Monoclmic, P2₁/c, Z = 4, a = 852.1(2), b = 766.1(2), c = 1558.3(3) pm, β = 92.65(2)°. Almost tetrahedral polyhedra [InX₄]^– (X = Br, I) are characteristic for both structures. The coordination number of Na⁺ is C.N. = 6 (NaInI₄; slightly distorted octahedron) and C.N. = 6+1+1 (NaInBr₄; distorted bicapped trigonal prism), respectively.     

Synthese und Kristallstrukturen der Tetrachlorozinkate SrZnCl4 und BaZnCl4

Synthesis and Crystal Structures of the Tetrachlorozincates SrZnCl₄ and BaZnCl₄ The tetrachlorozincates SrZnCl₄ and BaZnCl₄ are obtained from the respective binary chlorides at 550 °C in silica ampoules. SrZnCl₄ (tetragonal, I4₁/a, Z = 4, a = 650.40(7), c = 1437.0(2) pm) crystallizes with the scheelite type of structure, BaZnCl₄ (orthorhombic, Pnna, Z = 4, a = 724.15(6), b = 986.2(2), c = 947.71(8) pm) belongs to the GaCl₂ type of structure. The coordination polyhedra of the cations are the same in both compounds: Sr²⁺ and Ba²⁺ are surrounded by eight Cl^– (trigon‐dodecahedron), Zn²⁺ is tetrahedrally coordinated. For both compounds no phase transitions could be detected between 140 and 620 K.     

N-Methylierte Cyclotetrasilazane und Cyclotetrasiloxazane

Zusammenfassung Die achtgliedrigen Ringverbindungen IX (Rk. 1), XI (Rk. 12), XI (RRk. 13) und XIV (Rk. 9a) (vgl. Schema 1) wurden erstmalig, XII (Rkk. 4, 8; Schema 2) auf neuen Wegen dargestellt, ihre Eigenschaften beschrieben und ihre Struktur durch Massen-, IR-und NMR-Spektren bestätigt. Sie neigen bei thermischem deer katalytischem Einfluß zum Übergang in sechsgliedrige Ringverbindungen (vgl. Schema 3).

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N-Methylated cyclotetrasilazanes and cyclotetrasiloxazanes (chemistry of silicon-nitrogen compounds, CIV)

The eightmembered ring compounds IX (equ. 1), XI (equ. 12), XII (equ. 13) and XIV (equ. 9a) (see scheme 1) were prepared for the first time, XII (equ. 4, 8; scheme 2) on several new routes. Their properties are described and their structure confirmed by mass, infrared and nmr spectroscopy. They tend to transform by thermal or catalytic influence into sixmembered ring compounds (compare scheme 3).

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Herrn Prof. Dr. Dr. h. c.H. Nowotny gewidmet.

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103. Mitt.:U. Wannagat undL. Gerschler, Z. anorg. allgem. Chem. (im Druck).

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Mit Auszügen aus den Dissertationen a)F. Rabet und b)H. J. Wismar, Techn. Universität Braunschweig, 1971.     

Synthese,Komplexbildung und Kristallstrukturen von Cyclotriphosphazenen mit Pyridylalkylaminogruppen

Synthesis, Complex Formation and Crystal Structures of Cyclotriphosphazenes with Pyridylalkylamino Groups A variety of cyclotriphosphazenes with different numbers and types of functional pyridylalkylamino groups were synthesized by reactions of chlorophosphazenes with aminoalkylpyridine derivatives and completely characterized. The molecular structures of one multifunctional N‐donor ligand, N₃P₃(OC₆H₅)₅(NHCH₂CH₂C₅H₄N‐2) ( 1 ), was determined by X‐ray structure analysis. The hexafunctionalized derivative N₃P₃(NHCH₂CH₂C₅H₄N‐2)₆ ( 10 ) reacts with dichloromethane to form the HCl salt ( 10 a ) the structure of which could also determined by X‐ray crystal structure analysis. Complex formation of N₃P₃(OC₆H₅)₅(NHCH₂C₅H₄N‐3) ( 2 ) with cobalt(II) chloride yields the cobalt complex ( 2 a ) in which two molecules of the ligand are bonded to the tetrahedraly coordinated cobalt atom by the pyridine nitrogen atoms. The tetra functionalized ligand gem‐N₃P₃(OC₆H₅)₂(NHCH₂CH₂C₅H₄N‐2)₄ ( 8 ) forms the dinuclear cobalt‐cobaltate complex ( 8 a ) by interactions of a phosphazene nitrogen atom and the pyridine atoms of two cis‐vicinal functional groups with a CoCl unit and a pyridine group with a CoCl₃‐unit.     

Synthese,Charakterisierung und Kristallstrukturen von Tetraiodoferraten(III)

Preparation, Characterization, and Crystal Structures of Tetraiodoferrates(III) The extremely air and moisture sensitive tetraiodoferrates MFeI₄ with M = K, Rb and Cs have been synthesized by reaction of Fe, MI and I₂ at 300°C in closed quartz ampoules. The essentially more stable alkylammonium tetraiodoferrates NR₄FeI₄ with R = H, C₂H₅, n-C₃H₇, n-C₄H₉ and n-C₅H₁₁ can be obtained by reaction of Fe, NR₄I and I₂ in nitromethane. The Raman and UV/Vis-spectra of the black compounds show the existence of tetrahedral [FeI₄]^? ions in the structures. The crystal structure of the monoclinic CsFeI₄ (CsTlI₄ type, spgr P2₁/c; a = 7.281(1) Å; b = 17.960(3) Å; c = 8.248(2) Å; β = 107.35(15)°) is built up by tetrahedral [FeI₄]^? ions and CsI₁₁ polyhedra. The crystal structure of the orthorhombic (n-C₅H₁₁)₄NFeI₄ (spgr Pnna; a = 20.143(4) Å; b = 12.683(3) Å; c = 12.577(3) Å) contains tetrahedral [(n-C₅H₁₁)₄N]⁺ ions and [FeI₄]^? ions, respectively.     

Synthese und Kristallstrukturen ternärer Phosphide und Arsenide des Rhodiums und Iridiums

Ternary Phosphides and Arsenides of Rhodium and Iridium: Synthesis and Crystal Structures Single crystals of eight new compounds were prepared by heating mixtures of the elements in a lead flux. They were investigated by X‐ray methods. Ca₂Ir₁₂P₇ (a = 9.512(1), c = 3.923(1) Å)is an additional representative of the Zr₂Rh₁₂P₇ type structure, micro domains required refinements of the structural parameters in space group P6₃/m. Ca₅Rh₁₉P₁₂ (a = 12.592(1), c = 3.882(1) Å) and Ca₅Ir₁₉P₁₂ (a = 12.577(2), c = 3.954(1) Å) crystallize with the Ho₅Ni₁₉P₁₂ type structure (P6¯2m; Z = 1), whereas the compounds A₆Rh₃₀X₁₉ form a slightly modified structure of the Yb₆Co₃₀P₁₉ type. The lattice constants are: Ca₆Rh₃₀P₁₉: a = 15.532(1) Å, c = 3.784(1) Å Sr₆Rh₃₀As₁₉: a = 16.135(2) Å, c = 3.916(1) Å Eu₆Rh₃₀P₁₉: a = 15.566(1) Å, c = 3.821(1) Å Eu₆Rh₃₀As₁₉: a = 16.124(1) Å, c =5 3.903(3) Å Yb₆Rh₃₀P₁₉: a = 5 15.508(1) Å, c =5 3.770(1) Å Because one of the four non‐metal atoms, located on different crystallographic sites, is disordered along [001] micro domains are formed. Therefore the parameters were not refined in space group P6¯ (Yb₆Rh₃₀P₁₉ type), but in space group P6₃/m. The metal:non‐metal ratio of all compounds is in the range of 2:1. Accordingly most of the non‐metal atoms are coordinated by nine metal atoms, which form tricapped trigonal prisms. These polyhedra are combined with each other in a different way.     

Solvothermale Synthese und Bestimmung der Kristallstrukturen von AgBiI4 und Ag3BiI6

Solvothermal Synthesis and Crystal Structure Determination of AgBiI₄ and Ag₃BiI₆ AgBiI₄ and Ag₃BiI₆ were synthesized by solvothermal reaction from AgI and BiI₃ in diluted HI‐solution (20 %) at a temperature of 160 °C. The greyish‐black crystals grow as octahedra (AgBiI₄) or hexagonal/trigonal platelets (Ag₃BiI₆). AgBiI₄ crystallizes in space group Fd3¯m with a = 1222.3(1) pm (300 K) and Z = 8 whereas Ag₃BiI₆ shows the space group R3¯m with a = 435.37(6) pm, c = 2081.0(4) pm (300 K) and Z = 1. Both crystal structures show stacking sequence abcabc… of hexagonal layers containing Iodine. Bismuth and silver are sharing octahedral sites with different mass ratio in both structures. The part of silver which could be localized varies with temperature. This behaviour indicates mobility of silver within the crystal structure. The ionic conductivity of AgBiI₄ is explored. AgBiI₄ and Ag₃BiI₆ show close structural relationship, with AgBiI₄ as a variant with a higher degree of order.     

Lithium-bis(silyl)amide und Tris(silyl)amine Synthese und Kristallstrukturen

Lithium Bis(silyl)amides and Tris(silyl)amines Synthesis and Crystal Structures Lithiated di-tert-butylfluorosilylamine reacts with difluorosilanes by substitution ( 1, 2 ). The siloxy-( 3, 4 ) and tert-butyloxy-( 5 )-silylamines are formed in reaction of 1 and 2 with LiOR (R = SiMe₃, CMe₃). The lithium derivatives of 3 and 4 are dimers forming an (LiFSiN)₂-eight-membered ring ( 6, 7a ). Using 12 crown-4 the amide and the coordinated lithium are forming free ions ( 7 c ). The lithium derivative of 5 ( 8 ) crystallizes as a dimeric LiF-adduct of an iminosilane, forming a LiF-four-membered ring. In thf 7 reacts with Me₃SiCl by a fluorine/chlorine exchange and 9 is obtained. In 9 lithium is coordinated with nitrogen, oxygen and two thf molecules, forming an (SiNOLi)-four-membered ring. 6 and 7 react with fluorosilanes to give tris(silyl)amines 10 – 12 .     

Synthese und Kristallstrukturen neuer phosphorverbrückter bimetallischer Cluster der Elemente Quecksilber und Eisen

Synthesis and Crystal Structures of New Phosphorus‐bridged Bimetallic Clusters of the Elements Mercury and Iron The reaction of [Fe(CO)₄(HgX)₂] (X = Cl, Br) with P(SiMe₃)₂^tBu in the presence of tertiary phosphines and phosphinium salts leads to the ionic compounds [PPh₄]₂[Hg₁₂{Fe(CO)₄}₈(P^tBu)₄X₂] (X = Cl, Br) ( 1 , 2 ). If [Fe(CO)₄(HgX)₂] reacts with P(SiMe₃)₂^tBu the polymeric polynuclear complex [Hg₁₅{Fe(CO)₄}₃(P^tBu)₈Br₈]n ( 3 ) as well as the twenty mercury‐ and eight iron‐atoms containing [Hg₂₀{Fe(CO)₄}₈(P^tBu)₁₀X₄]‐clusters (X = Br, Cl) ( 4 , 5 ) are formed. The reaction of [Fe(CO)₄(HgX)₂] with LiPPh₂ yields to the phosphanido‐bridged [Hg₄{Fe(CO)₄}₂(PPh₂)₂Cl₂] ( 6 ), where as the use of LiP(SiMe₃)Ph leads to the diphosphinidene‐bridged cluster [Li(thf)₄]₂[Hg₁₀{Fe(CO)₄}₆(P₂Ph₂)₂Br₆] ( 7 ). The structures of the compounds 1–7 were characterized by X‐ray single crystal structure analysis.     

Synthese und Strukturuntersuchungen von Iodocupraten(I). IX. Synthese und Kristallstrukturen von Cs3Cu2I5 und RbCu2I3

Syntheses and Structure Analyses of Iodocuprates (I). IX. Syntheses and Crystal Structures of Cs₃Cu₂I₅ and RbCu₂I₃ Cs₃Cu₂I₅ and Rb[Cu₂I₃] were prepared by the reaction of CsI or RbI with CuI in solution (acetonitrile or acetone) or by solid state reaction. The crystal structure analysis of Cs₃Cu₂I₅ (orthorhombic, Pbnm, a = 1438.6(6), b = 1014.7(5), c = 1167.5(5) pm, Z = 4) shows, that the compound contains dinuclear anions Cu₂I₅^3? in which the I atoms are arranged to trigonal bipyramids; one Cu^I occupies one of the two I tetrahedral holes, the other a trigonal site of the neighbouring tetrahedron. Rb[Cu₂I₃] (orthorhombic, Cmcm, a = 1070.6(7), b = 1338.3(8), c = 572.8(3) pm, Z = 4) is built up by CuI₄ double chains; the compound is isomorphic with Cs[Cu₂I₃].     

Synthese und Kristallstrukturen von monomeren bis(thiophenolato)metall(II)-Komplexen

Preparation and Structures of Monomeric Bis(thiophenolato)metal(II) Complexes Sodium-2,4,6-tris(trifluoromethyl)thiophenolate (NaSR_f) reacts with MCl₂ (M = Zn, Pb) in the molar ratio of 2:1 to form the bis(thiophenolato)metal(II)complexes bis[2,4,6-tris(trifluoromethyl)thiophenolato]zinc 1 and bis[2,4,6-tris(trifluoromethyl)thiophenolato]lead 2 . Reaction of Mn[N(SiMe₃)₂]₂· THF with two equivalents of 2,4,6-tris(trifluoromethyl)thiophenol (R_fSH) forms Mn(SR_f)₂ · THF 3 . All compounds crystallize as THF adducts. The structures of Zn(SR_f)₂ · 2THF 1a , Pb(SR_f)₂ · THF 2a and Mn(SR_f)₂ · 2THF 3a are discussed.     

Synthese und Kristallstrukturen von DyPt8P2 und Mg10−xPt9P7

Synthesis and Crystal Structures of DyPt₈P₂ and Mg_10?xPt₉P₇ Single crystals of DyPt₈P₂ (a = 9.260(2), b = 4.005(1), c = 9.633(2) Å, β = 102.64(3)°) were grown by heating the elements in a melt of NaCl/KCl at 1100 °C. The phosphide crystallizes in a new type of structure (I2/m; Z = 2) which consists of fragments in the shape of a cubic close packing built up by three fourths of the platinum atoms. The Dy atoms are coordinated by twelve Pt and four P atoms forming a distorted hexagonal prism which is fourfold capped by Pt atoms. Needles of Mg_10?xPt₉P₇ (a = 18.121(4), b = 23.316(5), c = 3.848(1) Å) were obtained by reaction of the elements in molten lead at 1000 °C. The main feature of the new type of structure (Pbam; Z = 4) is an oval ring of pentagonal prisms formed by each six Pt and four P atoms. The prisms are linked with each other via common faces and they are centered by Mg atoms. Another Mg atoms are located in holes of the three‐dimensional [Pt₉P₇] network. It is remarkable, that one of the ten different crystallographic sites of the Mg atoms is occupied incompletely inducing the composition Mg_10?xPt₉P₇ with x = 0.86.     

Tellur-Polykationen stabilisiert durch Nioboxidhalogenide: Synthese und Kristallstrukturen von Te7NbOBr5 und Te7NbOCl5

Tellurium Cations stabilized by Niobium Oxytrihalides: Synthesis and Crystal Structure of Te₇NbOBr₅ and Te₇NbOCl₅ The reaction of Te₂Br with NbOBr₃ in a sealed evacuated glass ampoule at 225°C yields Te₇NbOBr₅ in form of bright black needles. Te₇NbOCl₅ is obtained from tellurium, TeCl₄ and NbOCl₃ at 220°C. Both compounds crystallize orthorhombic in the space group Pcca (Te₇NbOBr₅: a = 2 651,9(4) pm, b = 836.6(1) pm, c = 794.6(1) pm; Te₇NbOCl₅: a = 2 597.7(5) pm, b = 805.1(1) pm, c = 791.2(1) pm). The crystal structure determinations show that Te₇NbOBr₅ and Te₇NbOCl₅ are built of one-dimensional polymeric tellurium cations, one-dimensional associated pyramidal NbOX₄ groups (X = Cl, Br) and isolated halide anions. Magnetic properties of Te₇NbOX₅ were determined and confirm the expected diamagnetism. Te₇NbOX₅ can thus be formulated as [Te₇²⁺] [NbOX₄^?] (X^?). The charge distribution in the structure type Te₇MOX₅ (M = W, Nb; X = Cl, Br) became clear by synthesis and characterisation of the two niobium containing compounds.     

Synthese und spektroskopische Charakterisierung einiger Pentacarbonylwolfram(0)-Komplexe mit verschiedenen 1H-Phosphiren-Liganden,Kristallstrukturen von,und

Synthesis and Spectroscopic Characterization of some Pentacarbonyltungsten(0) Complexes with Various 1H-Phosphirene Ligands: Crystal Structures of , and The tungsten(0) complex 1 reacts upon heating with acetylene derivatives 2a–f in toluene to form benzonitrile and the complexes 4a–f ( 4a : R¹ ? Ph, R² ? H; 4b : R¹ ? Ph, R² ? CH₃; 4c : R¹ ? OEt, R² ? H; 4d : R¹ ? Ph, R² ? CO₂Et; 4e : R¹, R² ? CO₂Me; 4f : R¹, R² ? SiMe₃), which have been isolated by chromatography. Spectroscopic and mass spectrometric data are discussed. The crystal structures of the compounds 4a, b and d were determined by X-ray single crystal structure analysis ( 4a : space group P2₁/n, Z = 4, a = 937,5(2) pm, b = 2202,4(6) pm, c = 1266,3(4) pm, β = 108,94(4)°; 4b : space group P2₁/c, Z = 4, a = 1293,9(2) pm, b = 923,5(1) pm, c = 2223,4(3) pm, β = 92,385(6)°; 4d : space group P2₁/c, Z = 4, a = 955,2(2) pm, b = 3190,9(4) pm, c = 930,7(2) pm, β = 99,64(1)°).     

Synthese und Kristallstrukturen von Quecksilber(II)-iodid-Komplexen mit 3- und 4-pyridylmethylamino- sowie 4-pyridylmethoxy-substituierten Cyclophosphazen-Liganden

Synthesis and Crystal Structures of Mercury(II) Iodide Complexes with 3- and 4-Pyridylmethylamino- and 4-Pyridylmethoxy Substituted Cyclophosphazene Ligands Multifunctional cyclophosphazene ligands with 2-, 3-, and 4-pyridylalkylamino- or 4-pyridylmethoxy groups, N₃P₃(OC₆H₅)₅(NHCH₂(C₅H₄N-2)) ( 1 ), N₃P₃(OC₆H₅)₅ · (NHCH₂(C₅H₄N-3)) ( 2 ), N₃P₃(OC₆H₅)₅(NHCH₂(C₅H₄N-4)) ( 3 ) and N₃P₃(OC₆H₅)₅(OCH₂(C₅H₄N-4)) ( 4 ) are accessible through reactions of monochlorpentaphenoxycyclotriphosphaza-1,3,5-trien with aminomethylpyridine or pyridyl methanolate. 1 does not react with mercury(II) iodide whereas 2–4 yield the metal complexes 2 a , 3 a , and 4 a by interactions of the pyridyl nitrogen atoms. The X-ray single crystal structure analyses of these compounds shows that 2 a and 4 a are dimers, whereas 3 a is a HgI₂ polymer with syndiotacticaly arranged ligands.     

Synthese und Kristallstrukturen der Calcium‐Iridiumsilicide Ca3Ir4Si4 und Ca2Ir2Si

Synthesis and Crystal Structures of the Calcium Iridium Silicides Ca₃Ir₄Si₄ and Ca₂Ir₂Si The new compounds Ca₃Ir₄Si₄ und Ca₂Ir₂Si were prepared by reaction of the elemental components in sealed tantalum ampoules at 1200 °C. Their structures were determined from X‐ray single crystal data. Ca₃Ir₄Si₄(cubic, space group I4¯3m, a = 7.4171(2)Å, Z = 2) crystallizes with the Na₃Pt₄Ge₄ type structure. For Ca₂Ir₂Si (monoclinic, space group C2/c, a = 9.6567(5)Å, b = 5.8252(2)Å, c = 7.3019(4)Å, β = 100.212(2)°, Z = 4) a new structure was found. Chains of edge sharing, heavily distorted SiIr₄‐tetrahedra (Ir‐Si: 2.381 and 2.414Å) are connected via short Ir—Ir‐contacts (2.640Å) to form an open Ir/Si‐framework accommodating a three‐dimensional arrangement of calcium atoms (Ca—Ca: 3.413 ‐ 3.948Å).     

Synthese und Kristallstrukturen der quaternären Chalkogenidchloride AgBi2S3Cl und AgBi2Se3Cl

Synthesis and Crystal Structures of the Quaternary Chalcogenide Chlorides AgBi₂S₃Cl and AgBi₂Se₃Cl Grey crystals of AgBi₂S₃Cl and AgBi₂Se₃Cl were synthesized from AgCl and Bi₂S₃ or Bi₂Se₃by cooling stoichiometric melts from 790 K to room temperature. X‐ray diffraction on powders and single‐crystals revealed that the compounds crystallize isostructural with space group type P 2₁/m. In the crystal structure of AgBi₂S₃Cl the bismuth(III) cations have a capped trigonal prismatic coordination of sulfide and chloride ions. The prisms constitute a three‐dimensional framework by sharing common edges and faces. Silver(I) cations, which have a distorted octahedral coordination of sulfide ions, fill linear channels. Parallels to the crystal structures of Cu₃Bi₂S₄Cl and Pr₂Br₅ can be seen.     

Kristallstrukturen von Kalium- und Silbercyanamidonitrat

Pseudoelement Compounds. XV Crystal Structure Analysis of Potassium and Silver Cyanamidonitrate The crystal structures of potassium and silver cyanamidonitrate are reported. In both the potassium and the silver salt metal anion contacts via the atoms cyano-N, amide-N and oxygen are observed. The structural parameters of the ion [NO₂NCN]^– are only slightly influenced by the different environments (potassium, silver). K[NO₂NCN] forms a coordination lattice in which the nearest neighbours of the potassium ion are nine N and O atoms belonging to seven different anions. Ag[NO₂NCN] has a layer structure; the silver atoms are arranged in zickzack chains running perpendicular to the layers with an Ag–Ag distance of 3.169(1) Å.     

Hydratstufen und Kristallstrukturen von Bariumchlorid

Hydrates and crystal Structure of Barium Chloride The dehydrating process of BaCl₂ · 2H₂O and the phase transformations of BaCl₂ were observed by using a modified high temperature X-ray camera. The following compounds appeared with increasing temperature: BaCl₂ · 2H₂O → BaCl₂ · 1H₂O → BaCl₂(cubT) [BaCl₂(hex)]→ α-BaCl₂(ortho) → β-BaCl₂(cubH). The phase BaCl₂(cubT) is supposed to be the metastable low temperature form of β-BaCl₂(cubH). Structural relationships were demonstrated by comparing the different phases of the BaCl₂? H₂O system.