Einkristallzüchtung und Röntgenstrukturanalyse von CoSO4 · Pyrazin · 6 H2O (I) und (CoSO4)2 · Pyrazin · 12 H2O (II)

Crystal Growth and Structure of CoSO₄ · Pyrazine · 6 H₂O (I) and (CoSO₄)₂ · Pyrazine · 12 H₂O (II) Single crystals of μ-pyrazino-bis[pentaquacobalt(II)]-sulfate-dihydrate CoSO₄(pz) · 6 H₂O and Tetraqua-μ-pyrazino-cobalt(II)sulfate-dihydrate (CoSO₄)₂(pz) · 12 H₂O were grown by using gel methods and investigated by X-ray analysis. CoSO₄(pz) · 6 H₂O (I) shows monoclinic symmetry, space group C2/c; a = 1006.4(4) pm, b = 1026.9(4) pm, c = 1261.5(2) pm; β = 104.01(4)°; Z = 4. (CoSO₄)₂(pz) · 12 H₂O (II) shows orthorhombic symmetry, space group Pbam; a = 1262.3(4) pm, b = 1231.3(4) pm, c = 684.1(2) pm; Z = 2. CoSO₄ and Pyrazine crystallize in a polymeric (I) as well as in a dimeric (II) compound. In the polymeric compound the molecules are bonded by pyrazine to form alternating linear chains. The dimer is a dinuclear complex with a bridging pyrazine molecule.     

Die ersten Hydrogencarbonate mit einer trimeren [H2(CO3)3]4−-Baugruppe: Zur Darstellung und Kristallstruktur von Rb4H2(CO3)3 · H2O und K4H2(CO3)3 · 1,5 H2O

The First Hydrogencarbonates with a Trimeric [H₂(CO₃)₃]^4? Group: Preparation and Crystal Structure of Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1.5 H₂O Rb₄H₂(CO₃)₃ · H₂O and K₄H₂(CO₃)₃ · 1,5 H₂O were prepared by means of the reaction of (CH₃)₂CO₃ with RbOH resp. KOH in aqueous methanole. Trimer [H₂(CO₃)₃]^4?-anions were found in the crystal structure of Rb₄H₂(CO₃)₃ · H₂O (orthorhombic, Pnma (no. 62), a = 1 218.0(1) pm, b = 1 572.3(6) pm, c = 615.9(1) pm, V_EZ = 1 179.5(5) · 10⁶ pm³, Z = 4, R1(I ≥ 2σ(I)) = 0.027, wR2(I ≥ 2σ(I)) = 0.055). K₄H₂(CO₃)₃ · 1,5 H₂O crystallizes in an OD-structure. The determined superposition structure (orthorhombic, Pbam (no. 55), a = 1 161.8(1) pm, b = 597.0(1) pm, c = 383.85(3) pm, V_EZ = 266.3(1) · 10⁶ pm³, Z = 1, R1(I ≥ 2σ(I)) = 0.035, wR2(I ≥ 2σ(I)) = 0.074) can be derived from the structure of the rubidium compound. The thermal decomposition of the substances is discussed.     

Zur Kenntnis der Hydrate des Typs MX2 · 1 H2O mit M = Sr,Ba und X = Cl,Br, I. Kristallstrukturen des Strontiumchlorid-Monohydrats,SrCl2 · 1 H2O,und des Strontiumbromid-Monohydrats,SrBr2 · 1 H2O

On Hydrates of the Type MX₂ · 1 H₂O with M = Sr, Ba and X = Cl, Br, I. Crystal Structures of Strontium Chloride Monohydrate, SrCl₂ · 1 H₂O, and Strontium Bromide Monohydrate, SrBr₂ · 1 H₂O The structures of SrCl₂ · 1 H₂O, orthorhombic, Pnma, a = 1088.1(1), b = 416.2(1), c = 886.4(1) pm, Z = 4, d_c = 2.92 Mg m^?3, R = 0.052 for 755 reflections, and of SrBr₂ · 1 H₂O, orthorhombic, Pnma, a = 1146.4(1), b = 429,5(1), c = 922.9(1) pm, Z = 4, d_c = 3.88 Mg m^?3, R = 0.056 for 762 reflections have been determined from a Patterson synthesis and refined by Fourier and Least Squares methods. The structure consists of [SrX₂ = H₂O]_n-layers normal to [100] and Sr? H₂O? Sr? H₂O-chains parallel [010]. The Sr? O distances are 265.1(3) pm, SrCl₂ · 1 H₂O, and 265.9(4) pm, SrBr₂ · 1 H₂O. The shortest Sr? Cl and Sr? Br distances (298.9(1) and 315.3(1) pm) are within the layers. The environment of oxygen and strontium is a distorted tricapped trigonal prism. The orientation of the water molecules has been determined from vibrational spectroscopic measurements. The hydrogen atoms H₁ and H₂ form bifurcated hydrogen bonds of different strength to neighbouring halide ions. The corresponding O···X distances are 331.9(4) and 320.2(4) pm, SrCl₂ · 1 H₂O, and 340.8(4) and 333.8(4) pm, SrBr₂ · 1 H₂O. The other O? X distances are between 310.3(5) and 323.7(5) pm, SrCl₂ · 1 H₂O, and 323.5(5) and 333.2(6) pm, SrBr₂ · 1 H₂O.     

Über Kaliumdihalogenomonocyanomercurate(II) KHgX2CN · H2O (X = Cl,Br)

On Potassium Dihalogenomonocyanomercurates(II) KHgX₂CN · H₂O (X = Cl, Br) Hydrates of the dihalogenomonocyanomercurates KHgX₂CN · H₂O (X = Cl, Br) are obtained by reactions of equimoleculare amounts of HgX₂ and KCN in aqeuous solutions. The crystal structure of the rhombic KHgBr₂CN · H₂O (a = 454.2 pm; b = 1738.1 pm; c = 465.1 pm; Pmmm; Z = 2) contains linear HgBr₂ and Hg(CN)₂ groups and isolated Br^? and K⁺ ions. Therefore the compound can be formulated as a double salt Hg(CN)₂ · HgBr₂ · 2 KBr · 2 H₂O. The chloro compound is isotype.     

Synthese und Kristallstruktur von Ammin(μ3‐L‐glutamato)kupfer(II)

Synthesis and Crystal Structure of Ammine(μ₃‐L‐glutamato)copper(II) [Cu(L‐Glu)H₂O]·H₂O reacts with aqueous ammonia to give the ammine complex [Cu(L‐Glu)NH₃] ( 1 ). 1 forms orthorhombic crystals, space group P 2₁2₁2 with a = 1585,1(1) pm; b = 979,46(7) pm and c = 504,70(5) pm. In the crystal structure of 1 the copper atoms are linked by μ₃‐glutamate units to give a 2D layer structure. The copper atoms exhibit a square‐pyramidal coordination with two N atoms and two O atoms in the base plane and one O atom at the apex of the pyramid. The crystal structure is stabilized by a 3D network of N–H···O hydrogen bridges.     

Das Dreistoffsystem Kaliumazid-Strontiumazid-Wasser bei 268 K

Ternary System Potassium Azide – Strontium Azide – Water at 268 K The 268 K isotherm of the ternary system KN₃? Sr(N₃)₂? H₂O has been investigated by means of solubility measurements and x-ray methods. The following compounds were identified: KN₃; K₂Sr(N₃)₄ · 4 H₂O (orthorhombic, a = 1898, b = 1101, c = 624 pm, space group Cmmm); stable mixed crystals K_xSr_y(N₃)_4.69(H₂O)_6.62 with x = 2.08 to 1.34 and y = 1.30 to 1.67 (orthorhombic, a = 638 to 644, b = 1092 to 1082 and c = 627 to 623 pm, space group C222); metastable mixed crystals in the areas between stable mixed crystals and stoichiometric compounds; Sr(N₃)₂ · 5 H₂O (orthorhombic, a = 669, b = 1058, c = 611 pm, space group C222); Sr(N₃)₂ · 4 H₂O (orthorhombic, a = 643, b = 1096, c = 4396 pm).     

Synthese,Kristallstruktur und thermischer Abbau von Fluoroaluminaten der Zusammensetzung (NH4)[M(H2O)6][AlF6] (M = Zn,Ni), [Zn(H2O)6][AlF5(H2O)] und (PyH)4[Al2F10] · 4 H2O

Synthesis, Crystal Structure and Thermal Behaviour of Fluoroaluminates of the Composition (NH₄)[M(H₂O)₆](AlF₆) (M = Zn, Ni), [Zn(H₂O)₆][AlF₅(H₂O)], and (PyH)₄[Al₂F₁₀] · 4 H₂O Four new fluoroaluminates were obtained from fluoroacidic solutions of respective metal salts. The compounds of zinc ( I a : P2₁/c, a = 12.688(3), b = 6.554(1), c = 12.697(3) Å, β = 95.21(3)°, V = 1051.5(4) ų, Z = 4) and nickel ( I b : P2₁/c, a = 12.685(3), b = 6.517(1), c = 12.664(2)Å, β = 94.55(2)°, V = 1043.6(4) ų, Z = 4) are isotypic and represent a new structure type consisting of two different cations, NH₄⁺ and [M(H₂O)₆]²⁺ and [AlF₆]^3–‐anions. [Zn(H₂O)₆][AlF₅(H₂O)] ( II : C2/m, a = 10.769(2), b = 13.747(3), c = 6.487(1)Å, β = 100.02(3)°, V = 945.7(3) ų, Z = 4) is characterized by a H₂O/F‐disorder in the [AlF₅(H₂O)]‐octahedra in two trans positions. In (PyH)₄[Al₂F₁₀] · 4 H₂O ( III : Cmc2₁, a = 15.035(3), b = 20.098(4), c = 12.750(4) Å, V = 5364(2) ų, Z = 8), bioctahedral [Al₂F₁₀]^4– anions have been found for the first time. The structures are described and discussed in comparison. The new compounds were used as precursors in order to obtain new AlF₃‐phases. However, the thermal decomposition did not result in the formation of any new metastable AlF₃‐phase. Instead, phase mixtures of either α‐AlF₃ and β‐AlF₃ or AlF₃ and MF₂ were obtained.     

Strukturen und thermische Zersetzung von enH2(H3O)[AlF6] und enH2[AlF5(H2O)]

Structures and Thermal Decomposition of enH₂(H₃O)[AlF₆] and enH₂[AlF₅(H₂O)] By precipitation with ethylene diamine (en) from a hydrofluoric acid solution of aluminium enH₂(H₃O)[AlF₆] is formed. It crystallizes in the orthorhombic space group Pnma, a = 1084.9(1), b = 1079.4(1), c = 682.0(1) pm, R = 0.032. H₃O⁺ cations and [AlF₆]^3– anions are connected via strong H bonds to layers which are further linked to a 3 D network by H bonds from the enH₂²⁺ cations. By recrystallization from water or precipitation from a less acid solution enH₂[AlF₅(H₂O)] is formed, which crystallizes monoclinic in the space group P2₁ (a = 660.0(1), b = 563.5(1), c = 994.4(2) pm, β = 98.44(3)°, R = 0.029). The [AlF₅(H₂O)]^2– anions are linked by strong O–H…F bonding to form ‘einer-double chains' interconnected again via the enH₂²⁺ cations to a 3 D framework. Thermoanalytical investigations show that enH₂[AlF₅(H₂O)], by loss of water above 150 °C, as well as enH₂(H₃O)[AlF₆], by loss of water and HF above 120 °C, transform to enH₂AlF₅. The subsequent decomposition goes over NH₄⁺ containing intermediates towards β-AlF₃. Before decomposition the oxonium fluoroaluminate reveals a reversible phase transition at 99 °C.     

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.     

Über die Pentachlorothallate(III) K2TlCl5 · 2 H2O und M2TlCl5 · H2O (M = Rb,NH4)

On the Pentachlorothallates(III) K₂TlCl₅ · 2 H₂O and M₂TlCl₅ · H₂O (M = Rb, NH₄) The pentachlorothallates(III) K₂TlCl₅ · 2 H₂O and M₂TlCl₅ · H₂O (M = Rb, NH₄) were obtained by crystallization from aqueous solutions of TlCl₃ and MCl. The crystal structure of the monoclinic K₂TlCl₅ · 2 H₂O contains dimeric Tl₂Cl₁₀ anions formed by two edge sharing octahedra. The orthorhombic monohydrates are isotypic with Cs₂[TlCl₅(OH₂)].     

Carbonat‐Hydrate der schweren Alkalimetalle: Darstellung und Struktur von Rb2CO3 · 1,5 H2O und Cs2CO3 · 3 H2O

Carbonate Hydrates of the Heavy Alkali Metals: Preparation and Structure of Rb₂CO₃ · 1.5 H₂O und Cs₂CO₃ · 3 H₂O Rb₂CO₃ · 1.5 H₂O and Cs₂CO₃ · 3 H₂O were prepared from aqueous solution and by means of the reaction of dialkylcarbonates with RbOH and CsOH resp. in hydrous alcoholes. Based on four‐circle diffractometer data, the crystal structures were determined (Rb₂CO₃ · 1.5 H₂O: C2/c (no. 15), Z = 8, a = 1237.7(2) pm, b = 1385.94(7) pm, c = 747.7(4) pm, β = 120.133(8)°, V_EZ = 1109.3(6) · 10⁶ pm³; Cs₂CO₃ · 3 H₂O: P2/c (no. 13), Z = 2, a = 654.5(2) pm, b = 679.06(6) pm, c = 886.4(2) pm, β = 90.708(14)°, V_EZ = 393.9(2) · 10⁶ pm³). Rb₂CO₃ · 1.5 H₂O is isostructural with K₂CO₃ · 1.5 H₂O. In case of Cs₂CO₃ · 3 H₂O no comparable structure is known. Both structures show [(CO₃^2–)(H₂O)]‐chains, being connected via additional H₂O forming columns (Rb₂CO₃ · 1.5 H₂O) and layers (Cs₂CO₃ · 3 H₂O), respectively.     

Crystal Structures and Raman Spectra of cis‐[SnCl4(H2O)2]·2H2O,cis‐[SnCl4(H2O)2]·3H2O, [Sn2Cl6(OH)2(H2O)2]·4H2O,and [HL][SnCl5(H2O)]·2.5H2O (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime,C18H18N4O2)

The complexes cis‐[SnCl₄(H₂O)₂]·2H₂O ( 1 ), [Sn₂Cl₆(OH)₂(H₂O)₂]·4H₂O ( 3 ), and [HL][SnCl₅(H₂O)]·2.5H₂O ( 4 ) were isolated from a CH₂Cl₂ solution of equimolar amounts of SnCl₄ and the ligand L (L=3‐acetyl‐5‐benzyl‐1‐phenyl‐4, 5‐dihydro‐1, 2, 4‐triazine‐6‐one oxime, C₁₈H₁₈N₄O₂) in the presence of moisture. 1 crystallizes in the monoclinic space group Cc with a = 2402.5(1) pm, b = 672.80(4) pm, c = 1162.93(6) pm, β = 93.787(6)° and Z = 8. 4 was found to crystallize monoclinic in the space group P2₁, with lattice parameters a = 967.38(5) pm, b = 1101.03(6) pm, c = 1258.11(6) pm, β = 98.826(6)° and Z = 2. The cell data for the reinvestigated structures are: [SnCl₄(H₂O)₂]·3H₂O ( 2 ): a = 1227.0(2) pm, b = 994.8(1) pm, c = 864.0(1) pm, β = 103.86(1)°, with space group C2/c and Z = 4; 3 : a = 961.54(16) pm, b = 646.29(7) pm, c = 1248.25(20) pm, β = 92.75(1)°, space group P2₁/c and Z = 4.     

[(C2H5)3NH]2Sn3Se7 · 0,25 H2O und [(C3H7)2NH2]4Sn4Se10 · 4 H2O

Synthesis, Structure, and Properties of Some Selenidostannates. II. [(C₂H₅)₃NH]₂Sn₃Se₇ · 0,25 H₂O and [(C₃H₇)₂NH₂]₄Sn₄Se₁₀ · 4 H₂O The new selenidostannate hydrates [(C₂H₅)₃NH]₂Sn₃Se₇ · 0.25 H₂O ( I ) and [(C₃H₇)₂NH₂]₄Sn₄Se₁₀ · 4 H₂O ( II ) were synthesized from an aqueous suspension of triethylammonium (tripropylammonium), tin, selenium I and in addition sulfur II at 130 °C. I crystallizes at ambient temperature in the monoclinic space group P2₁/n (a = 2069,3(4) pm, b = 1396,6(3) pm, c = 2342,8(5) pm, β = 114,68(3)°, Z = 8) and is characterized by two different anions, chains from edge‐sharing [Se₃Se₇]^2– units and nets from trigonal SnSe₅ bipyramids. II crystallizes at ambient temperature in the tetragonal space group I4₁/amd (a = 2150,0(3) pm, c = 1174,4(2) pm, Z = 4) and contains adamantane like [Sn₄Se₁₀]^4–‐cages. The UV‐VIS spectra of the selenidostannates demonstrate that the absorption edges red shift as the dimensionality of the compounds is increased.     

Erdalkali-Fluoromanganate(III): BaMnF5 · H2O und SrMnF5 · H2O

Alkaline Earth Fluoromanganates(III): BaMnF₅ · H₂O and SrMnF₅ · H₂O Solid BaF₂ or SrF₂ forms with solutions of Mn³⁺ in aqueous hydrofluoric acid precipitates of hitherto unknown BaMnF₅ · H₂ and SrMnF₅ · H₂O respectively. X-ray structure determination on single crystals of both isotypic compounds (space group P2₁/m, Z = 2; BaMnF₅ · H₂O: a = 537.0(3), b = 817.2(2), c = 628.0(4) pm β = 111.17(5)°, R_w = 0.035 for 1403 reflections; SrMnF₅ · H₂O: a = 510.8(1), b = 792.0(2), c = 610.6(1) pm, β = 110.24(1)° R_w = 0.068 for 539 reflections) reveal pure [MnF₆]^3? octahedra connected with each other to infinite chains by sharing trans corners. The H₂O molecules are coordinated to the alkaline earth ions only and form weak O? H…F hydrogen bonds. The pronounced weakening of the Mn? F bonds within the chain direction (Mn? F 2X 212.7(1)/210.8(5) pm, 2X 183.8(3)/181.8(9) pm, 2X 186.9(2)/187.2(8) pm) may be due by halves to the Jahn-Teller-effect as can be deduced by bond valence calculations.     

Synthese und Kristallstruktur der Rhenium(VII)‐Nitridchloride ReNCl4 und ReNCl4·H2O

Syntheses and Crystal Structures of the Rhenium(VII) Nitride Chlorides ReNCl₄ and ReNCl₄·H₂O Rhenium(VII) nitride chloride, ReNCl₄ ( 1 ) is obtained in form of brown needles with metallic luster by the reaction of ReCl₅ with Cl₃VNCl at 140 °C under vacuum in a sealed glass ampoule. It crystallizes in the tetragonal space group I4 with the lattice parameters a = 826.7(4), c = 405.1(2) pm, and Z = 2. The square pyramidal molecules are connected by asymmetric nitrido bridges to form chains along the crystallographic c axis. The shorter Re‐N distance of 163.0(5) pm corresponds to a triple bond, while the pronounced longer distance of 242.0(5) pm can be interpreted with a weak donor bond. The reaction of ReCl₅ with VN at 170 °C under vacuum in a sealed glass ampoule yields red needles of ReNCl₄·H₂O ( 2 ). It crystallizes in the orthorhombic space group Pnma with a = 1075.4(2), b = 1108.5(2), c = 547.7(5) pm and Z = 4. The Re atoms exhibit a distorted octahedral coordination with the aqua ligand in trans position to the nitrido ligand. The Re‐N triple bond has a bond distance of 166.1(11) pm. The complexes are connected by hydrogen bridges O‐H···N to form chains.     

Competitive Coordination of the Uranyl ion by Perchlorate and Water – The Crystal Structures of UO2(ClO4)2·3H2O and UO2(ClO4)2·5H2O and a Redetermination of UO2(ClO4)2·7H2O (Z. Anorg. Allg. Chem. 2003, 629, 1012–1016)

In the article “Competitive Coordination of the Uranyl ion by Perchlorate and Water – The Crystal Structures of UO₂(ClO₄)₂·3H₂O and UO₂(ClO₄)₂·5H₂O and a Redetermination of UO₂(ClO₄)₂·7H₂O” (Z. Anorg. Allg. Chem. 2003 , 629, 1012–1016), some wrong parameters and bond lengths for UO₂(ClO₄)₂·7H₂O were given in table 1 and table 3 The correct parameters are: a = 1449.5(2) pm, b = 921.6(1) pm, c = 1067.5(2) pm, V = 1422.5(4)·10⁶ pm³, ρ = 2.712 g·cm^?3, μ = 119 cm^?1. The corrected bond lengths for this structure are U–O(1) 175.8(5) pm, U–O(2) 239.1(5) pm, U–O(3) 240.8(5), U–O(4) 242.0(7). A cif file with the correct data has been deposited with the ICSD.     

Darstellung und Struktur der ersten gemischten Alkalimetallhydrogencarbonate NaA2[H(CO3)2] · 2H2O mit A = K,Rb

Preparation and Crystal Structure of the First Mixed Alkalimetal Hydrogencarbonates NaA₂[H(CO₃)₂] · 2H₂O with A = K, Rb The new hydrogencarbonates NaK₂[H(CO₃)₂] · 2H₂O (Pnma, a = 934.07(13) pm, b = 789.31(10) pm, c = 1142.1(5) pm, V_EZ = 842.0(4) · 10⁶ pm³, Z = 4, R1 (I ? 2σ(I)) = 0.023, wR2 = 0.066 for 989 reflections) and NaRb₂[H(CO₃)₂] · 2H₂O (Pnma, a = 948.24(11) pm, b = 811.37(9) pm, c = 1189.0(2) pm, V_EZ = 914.8(2) · 10⁶ pm³, Z = 4, R1 (I ≤ 2σ(I)) = 0.031, wR2 = 0.077 for 1063 reflections) were prepared from aqueous solutions. The crystal structures were determined. The isostructural compounds contain dimeric, non centrosymmetric [H(CO₃)₂]^3? anions. In NaK₂[H(CO₃)₂] · 2H₂O a short hydrogen bond (d(O … O) = 246.1(2) pm) with an asymmetric potential was detected. In NaRb₂[H(CO₃)₂] · 2H₂O a hydrogen bond with symmetric potential (d(O … O) = 247.8(5) pm) can be assumed. The IR-spectra of NaK₂[H(CO₃)₂] · 2H₂O and Na₃[H(CO₃)₂] · 2H₂O are compared.     

Hydrate des Cer(III)-chlorids

Hydrates of Cerium(III) Chloride The thermal dehydration of CeCl₃ · 7 H₂O to CeCl₃ gives four definite intermediates: CeCl₃ · 6 H₂O, CeCl₃ · 3 H₂O, CeCl₃ · 2 H₂O, CeCl₃ · H₂O. In the hexahydrate monomeric [CeCl₂(H₂O)₆]⁺ units exist. A structure analysis of CeCl₃ · 3 H₂O gave an orthorhombic unit cell (S.G. Pnma; Z = 4) with a = 1 242.7(4) pm; b = 881.8(8) pm, c = 693.4(5) pm. The structure consists of [CeCl_4/2Cl(H₂O)₃] chains, where two Ce³⁺ ions are connected via two chloride ions, forming bent chains in the [010] direction. The trihydrates LnCl₃ · 3 H₂O (Ln = Pr? Tb) are isotypic, also one modification of LaCl₃ · 3 H₂O. The structures of the di- and mono-hydrate are not yet known. Molar volumina and solution enthalpies in water vary linearly with the number of H₂O molecules per formula unit.     

Crystal Structure and Thermal Behaviour of K2[CrF5·H2O]

K₂[CrF₅·H₂O] is monoclinic: a = 9.6835(3) Å, b = 7.7359(2) Å, c = 7.9564(3) Å, β = 95.94(1)°, Z = 4, space group C2/c (n^o 15). Its crystal structure was solved from its X‐ray powder pattern recorded on a powder diffractometer, using for the refinement the Rietveld method. It is built up from isolated octahedral [CrF₅·OH₂]^2? anions separated by potassium cations. The dehydration of K₂[CrF₅·H₂O] leads to anhydrous orthorhombic K₂CrF₅: a = 7.334(2) Å, b = 12.804(4) Å, c = 20.151(5) Å, Z = 16, space group Pbcn (n^o 60), isostructural with K₂FeF₅.     

Synthese,Struktur und Eigenschaften von [(C4H9)2NH2]4[Sn2Se6], [(C4H9)2NH2]4[Sn4Se10] · 2 H2O und [(C3H7)3NH]2[Sn3Se7]

About Selenidostannates. I Synthesis, Structure, and Properties of [Sn₂Se₆]^4–, [Sn₄Se₁₀]^4–, and [Sn₃Se₇]^2– The selenidostannates [(C₄H₉)₂NH₂]₄Sn₂Se₆ · H₂O ( I ), [(C₄H₉)₂NH₂]₄Sn₄Se₁₀ · 2 H₂O ( II ) und [(C₃H₇)₃NH]₂Sn₃Se₇ ( III ) were prepared by hydrothermal syntheses from the elements and the amines. I crystallizes in the monoclinic spacegroup P2₁/n (a = 1262.9(3) pm, b = 1851.3(4) pm, c = 2305.2(4) pm, β = 104.13(3)° and Z = 4). The [Sn₂Se₆]^4– anion consists of two edge‐sharing tetrahedra. II crystallizes in the orthorhombic spacegroup Pna2₁ (a = 2080.3(4) pm, b = 1308.2(3) pm, c = 2263.5(5) pm and Z = 4). The anion is formed from four SnSe₄ tetrahedra which are joined by common corners to the adamantane cage [Sn₄Se₁₀]^4–. III crystallizes in the orthorhombic spacegroup Pbcn (a = 1371.1(3) pm, b = 2285.4(5) pm, c = 2194.7(4) pm and Z = 8). The anion is a chain, built from edge‐sharing [Sn₃Se₅Se_4/2]^2– units, in which two corner sharing tetrahedra are connected to a trigonal bipyramid by an edge of one and a corner of the other tetrahedron. The results of the TG/DSC measurements and of temperature dependent X‐ray diffractograms reveal that I and II decompose at first by release of minor quantities of triethylammonium to compounds with layer structure and larger cell dimensions. At still higher temperature the rest of triethylammonium and H₂Se is evolved, leaving SnSe₂ and Se in the bulk. The former decomposes partially at the highest temperature to SnSe. In the measurements of III the complex intermediate compound was not observed. III decomposes directly to SnSe₂.