Darstellung und Kristallstruktur von K4[SnO3]

Preparation and Crystal Structure of K₄[SnO₃] K₄[SnO₃] crystallizes with the K₄[PbO₃] structure in the orthorhombic spacegroup Pbca (No. 61) with the lattice constants a = 652.2(3) pm, b = 1 112.1(5) pm and c = 1 893.7(7) pm. In the structure isolated ψ-tetrahedral anions [Sn^IIO₃]^4? are arranged in layers perpendicular [001]. The structure of K₄[SnO₃] will be compared with those of stannates and plumbates of composition A₄[M^IIO₃] (A = Na, K, Rb, Cs) and with the known potassium stannates(II).     

Kristallstrukturen von Octacyanomolybdaten(IV). III [1] (NMe4)3Li[Mo(CN)8] · 3,5 H2O und Cs7Na[Mo(CN)8]2 · 4,17 H2O: Beispiele für dodekaedrische und quadratisch-antiprismatische Achterkoordination

Crystal Structures of Octacyanomolybdates(IV). III (NMe₄)₃Li[Mo(CN)₈] · 3.5 H₂O and Cs₇Na[Mo(CN)₈]₂ · 4.17 H₂O: Examples of Dodecahedral and Square Antiprismatic Eight-Coordination At single crystals of the hydrated tetragonal cyano complexes (NMe₄)₃Li[Mo(CN)₈] · 3.5 H₂O (a = 1707.5(3), c = 1054.9(2) pm, space group P42₁m, Z = 4) and Cs₇Na[Mo(CN)₈]₂ · 4.17 H₂O (a = 1547.9(1), c = 3254.6(6) pm, I4₁/a, Z = 8) X-ray structure determinations were performed. The [Mo(CN)₈]^4– polyhedra agree with respect to their mean distances Mo–C and C–N (216,7/114,3 pm resp. 216,1/114,7 pm) within their standard deviations, however, there is a distorted dodecahedron in the first case ((NMe₄)₃Li-complex), and a distorted square antiprism in the second (Cs₇Na-complex). The coordination of the counter cations, partly hydrated, the formation of hydrogen bridges and the packing of the complex anions is discussed.     

Synthese und Kristallstruktur von [Na(12-Krone-4)2]2[Hg(Se4)2] · 1,5 DMF

Synthesis and Crystal Structure of [Na(12-Crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF . The title compound has been prepared by the reaction of Na₂Se₄ with mercury acetate in DMF solution in the presence of 15-crown-5, forming dark red crystal needles. [Na(12-crown-4)₂]₂[Hg(Se₄)₂] · 1.5 DMF crystallizes in the space group C2/c with eight formula units per unit cell. The structure was determined with 3 824 observed unique reflections, R = 0.085. Lattice dimensions at - 70°C: a = 2 884(2), b = 1 407.7(7), c = 2 843(2) pm, β = 93.93(5)°. The structure consists of [Na(12-crown-4)₂]⁺ ions with a sandwichlike coordination of the crown ether molecules, and of [Hg(Se₄)₂]^2? ions, in which the mercury atom is coordinated by two tetraselenido ions in a chelating fashion. The [Hg(Se₄)₂]^2? ions are arranged to infinite chains via Se…?Se contacts.     

Synthese,Kristallstruktur und Festkörper-NMR-spektroskopische Untersuchungen von K5H(CN2)3

Synthesis, Crystal Structure, and Solid State MAS-NMR Spectroscopic Investigation of K₅H(CN₂)₃ Single phase K₅H(CN₂)₃ was synthesized by reaction of KHCN₂ with metallic potassium in liquid ammonia or by reaction of KNH₂ with melamine C₃N₃(NH₂)₃ at 320 °C, respectively. The crystal structure was determined from X-ray powder and single crystal data: K₅H(CN)₃, space group Im3m, a = 795.68(7) pm, Z = 2, R1 = 0.025, wR2 = 0.0438. In the solid K₅H(CN₂)₃ contains K⁺ and CN₂^2–, the anions exhibit D_∞h symmetry. According to ¹H and ¹³C solid state MAS-NMR investigations, temperature dependent impedance spectroscopy, and FTIR spectroscopy the protons are only loosely bound to the CN₂^2– ions. The proton conductivity shows a sharp increase above 70 °C.     

Kristallstruktur von Tetraphenylphosphonium-Monothiocyanatohydro-closo-Decaborat, [P(C6H5)4]2[2-(SCN)B10H9] · CH3CN

Crystal Structure of Tetraphenylphosphonium Monothiocyanatohydro-closo-Decaborate, [P(C₆H₅)₄]₂[2-(SCN)B₁₀H₉] · CH₃CN The X-ray structure determination of [P(C₆H₅)₄]₂[2-(SCN)B₁₀H₉] · CH₃CN (monoclinic, space group P2₁/n, a = 10.6040(10), b = 13.8880(9), c = 33.888(3) Å, β = 94.095(8)°, Z = 4) reveals the S coordination of the SCN substituent with a B? S distance of 1.913(6) Å and a B? S? C angle of 105.3(3)°. The SCN group is nearly linear (178.2(7)°).     

Darstellung und Kristallstruktur von Tetraphenylphosphonium-Hexathiocyanatorhodat(III), [P(C6H5)4]3[Rh(SCN)6]

Preparation and Crystal Structure of Tetraphenylphosphonium Hexathiocyanatorhodate(III), [P(C₆H₅)₄]₃[Rh(SCN)₆] By treatment of RhCl₃ · n H₂O with KSCN in water a mixture of the linkage isomers [Rh(NCS)_n(SCN)_6–n]^3?, n = 0–2 is formed which is separated by ion exchange chromatography on diethylaminoethyl cellulose. The X-ray structure determination on a single crystal of [P(C₆H₅)₄]₃[Rh(SCN)₆] (monoclinic, space group C1c1, a = 13.620(5), b = 22.929(13), c = 22.899(9) Å, β = 98.55(3)°, Z = 4) confirms the coordination of all ligands via S with the middle Rh? S distance of 2.372 Å and Rh? S? C angles of 109°. The SCN groups are nearly linear with 175° and averaged bondlengths S? C 1.63 and C? N 1.14 Å. The crystal lattice is build up by layers of complex anions and voluminous cations with no specific interactions but which are closely connected by thiocyanate ligands and phenyl rings.     

Die Kristallstruktur des „supramolekularen”︁ Cadmiumcyanid-Hexamethylentetramin-Addukts [Cd(CN)2 · 2/3 C6H12N4]

The Crystal Structure of the “Supramolecular” Cadmiumcyanide-Hexamethylenetetramine Adduct [Cd(CN)₂ · 2/3 C₆H₁₂N₄] Single crystals of a new compound in the system Cd(CN)₂-hexamethylenetetramine (HMTA) with the composition [Cd(CN)₂ · 2/3 C₆H₁₂N₄] were obtained by crystallization from an aqueous solution containing Cd(CN)₂ and HMTA. The structure consists of a ?supramolecular”? network of ? Cd? CN? Cd- and ? Cd? HMTA? Cd-chains. The structure is compared with that of an already known compound [Cd(CN)₂ · 1/3 C₆H₁₂N₄].     

Phosphaniminato-Komplexe Seltener Erden. Synthese und Kristallstrukturen von [M2(C5H5)3(NPPh3)3] · 3 C7H8 mit M = Y,Dy und Er. Magnetische Eigenschaften von [Dy2(C5H5)3(NPPh3)3] · 3 C7H8

Phosphoraneiminato Complexes of Rare Earths Elements. Syntheses and Crystal Structures of [M₂(C₅H₅)₃(NPPh₃)₃] · 3 C₇H₈ mit M = Y, Dy, and Er. Magnetic Properties of [Dy₂(C₅H₅)₃(NPPh₃)₃] · 3 C₇H₈ The title compounds have been prepared by reactions of the cyclopentadienidchlorides [M(C₅H₅)₂Cl]₂ with LiNPPh₃ in boiling toluene, and they were characterized by crystal structure determinations. All three compounds crystallize isotypicly with one another within the orthorhombic space group Pbca with Z = 8. Two of the three phosphoraneiminato groups link the metal atoms via μ₂-N atoms to almost planar M₂N₂ four-membered rings. The third NPPh₃^– group is terminally bonded. The magnetic susceptibility of [Dy₂(C₅H₅)₃(NPPh₃)₃] · 3 C₇H₈ has been determined (SQUID magnetometer) in the temperature range 1.7 K–300 K at magnetic fields between 0.01 T and 5 T. Calculations based on a cubic ligand field model lead to a satisfactory simulation with reasonable ligand field parameters. The inclusion of isotropic intramolecular exchange interactions in the model does not improve the fit, so that in the framework of the applied model no hints to a spin-spin coupling within the dinuclear units are obtained.     

IV Dodekaedrische [Mo(CN)8]‐Koordination in den cyanoverbrückten Cobalt‐ und Nickel‐Amminkomplexen MII2(NH3)8[Mo(CN)8] · 1,5 H2O (MII = Co,Ni) und Ni2(NH3)9[Mo(CN)8] · 2 H2O

Crystal Structures of Octacyanomolybdates(IV). IV Dodecahedral [Mo(CN)₈] Coordination of the Cyano‐Bridged Cobalt and Nickel Ammin Complexes M^II₂(NH₃)₈[Mo(CN)₈] · 1.5 H₂O (M^II = Co, Ni) and Ni₂(NH₃)₉[Mo(CN)₈] · 2 H₂O At single crystals of the hydrated cyano complexes Co₂(NH₃)₈[Mo(CN)₈] · 1.5 H₂O (a = 910.0(4), b = 1671(2), c = 1501(1) pm, β = 93.76(6)°) and Ni₂(NH₃)₈[Mo(CN)₈] · 1.5 H₂O (a = 899.9(9), b = 1654.7(4), c = 1488(1) pm, β = 94.01°), isostructurally crystallizing in space group P2₁/c, Z = 4, and of trigonal Ni₂(NH₃)₉[Mo(CN)₈] · 2 H₂O (a = 955.1(1), c = 2326.7(7) pm, P3₁, Z = 3), X‐ray structure determinations were performed at 168 resp. 153 K. The [Mo(CN)₈]^4– groups of the three compounds, prepared at about 275 K and easily decomposing, show but slightly distorted dodecahedral coordination (mean distances Mo–C: 216.3, 215.4 and 216.1 pm). Within the monoclinic complexes the anions twodimensionally form cyano bridges to the ammin cations [M(NH₃)₄]²⁺ and are connected with the resulting [MN₆] octahedra (Co–N: 215.1 pm, Ni–N: 209.8 pm) into strongly puckered layers. The trigonal complex exhibits a chain structure, as one [Ni(NH₃)₅]²⁺ cation is only bound as terminal octahedron (Ni–N: 212.0 pm). Details and the influence of hydrogen bridges are discussed.     

Amido-Komplexe von Mangan(II). Synthese und Kristallstrukturen von [Mn(NPh2)2(THF)]2 und Na2[Mn(NPh2)4] · 2 C7H8

Amido Complexes of Manganese(II). Syntheses and Crystal Structures of [Mn(NPh₂)₂(THF)]₂ and Na₂[Mn(NPh₂)₄] · 2 C₇H₈ The silylated amido complex [Mn{N(SiMe₃)₂}₂ · (THF)] reacts in toluene solution with diphenylamine under ligand exchange to form the diphenylamido complex [Mn(NPh₂)₂(THF)]₂ ( 1 ), which forms orange-red columnar crystals. 1 reacts in THF solution with NaN(SiMe₃)₂ and after crystallization from toluene yellow-orange Na₂[Mn(NPh₂)₄] · 2 C₇H₈ ( 2 ) is obtained. According to the crystal structure analyses the manganese atoms in 1 (space group P2₁/c, Z = 2) are linked via the N atoms of two of the NPh₂^– groups to form centrosymmetric Mn₂N₂ four-membered rings with Mn–N bonds of almost the same length. 2 (space group I4₁/a, Z = 4) forms a three-dimensional space-lattice structure, which arises from ”︁inner solvation”︁”︁ of the sodium atoms with the phenyl rings of the NPh₂^– group.     

Phosphaniminate von Alkalimetallen: Die Kristallstrukturen von [KNPCy3]4, [KNPCy3]4·2OPCy3, [CsNPCy3]4·4OPCy3 und [Li4(NPPh3)(OSiMe2NPPh3)3(DME)]

The alkalimetal phosphoraneiminates [KNPCy₃]₄, ( 1 ) [KNPCy₃]₄·2OPCy₃ ( 2 ) and [CsNPCy₃]₄·4OPCy₃ ( 3 ) (Cy = cyclohexyl) which are obtainable by the reaction of pottassium amide or cesium amide with Cy₃PI₂ or Cy₃PBr₂ in liquid ammonia, as well as the lithium derivative [Li₄(NPPh₃)(OSiMe₂NPPh₃)₃(DME)] ( 4 ) have been characterized by crystal structure determinations. 4 has been formed by the insertion reaction of silicon greaze (‐OSiMe₂)n into the LiN bonds of [LiNPPh₃]₆ in DME solution (DME = 1, 2‐dimethoxyethane). 1 : Space group P&1macr;, Z = 2, lattice dimensions at 193 K: a = 1389.8(1); b = 1408.1(1); c = 2205.2(2) pm; α = 78.952(10)?; β = 81.215(10)?; γ = 66.232(8)?; R1 = 0.0418. 2 : Space group Pbcn, Z = 4, lattice constants at 193 K: a = 2943.6(2); b = 2048.2(1); c = 1893.8(1) pm; R1 = 0.0428. 3 : Space group Cmc2₁, Z = 4, lattice dimensions at 193 K: a = 2881.6(2); b = 2990.2(2); c = 1883.7(2) pm; R1 = 0.0586. 4 ·1/2DME: Space group R&3macr;c, Z = 12, lattice dimensions at 193 K: a = b = 1583.5(1); c = 11755.3(5) pm; R1 = 0.0495. All complexes have heterocubane structures. In 1‐3 they are formed by four alkali metal atoms and by the nitrogen atoms of the (μ₃‐NPCy₃^‐) groups, whereas 4 forms a "heteroleptic" Li₄NO₃ heterocubane.     

Kristallstruktur von Natrium‐Dihydrogencyamelurat‐Tetrahydrat Na[H2(C6N7)O3] · 4 H2O

Crystal Structure of Sodium Dihydrogencyamelurate Tetrahydrate Na[H₂(C₆N₇)O₃] · 4 H₂O Sodium dihydrogencyamelurate‐tetrahydrate Na[H₂(C₆N₇)O₃]·4 H₂O was obtained by neutralisation of an aqueous solution, previously prepared by hydrolysis of the polymer melon with sodium hydroxide. The crystal structure was solved by single‐crystal X‐ray diffraction ( a = 6.6345(13), b = 8.7107(17), c = 11.632(2) Å, α = 68.96(3), β = 87.57(3), γ = 68.24(3)°, V = 579.5(2) ų, Z = 2, R1 = 0.0535, 2095 observed reflections, 230 parameters). Both hydrogen atoms of the dihydrogencyamelurate anion are directly bound to nitrogen atoms of the cyameluric nucleus, thus proving the preference of the keto‐tautomere in salts of cyameluric acid in the solid‐state. The compound forms a layer‐like structure with an extensive hydrogen bonding network.     

Synthese und Kristallstruktur von [WNCl3 · NC–Ph]4 · 3 CH2Cl2

Synthesis and Crystal Structure of [WNCl₃ · NCPh]₄ · 3 CH₂Cl₂ The adduct of tungsten nitride trichloride with benzonitrile, [WNCl₃ · NCPh]₄, is formed by the reaction of N,N,N'-tris(trimethylsilyl)benzamidine and tungsten hexachloride in CCl₄ solution. It forms red crystal needles and was characterized by its IR spectrum and an X-ray crystal structure determination (1983 unique observed reflexions, R = 0.075). Crystal data: a = 1464.8, b = 1902.6, c = 2033.8 pm, β = 102.27°, space group C2/c, Z = 4. In the [WNCl₃ · NCPh]₄ molecule the tungsten atoms were located at the vertices of a square and are linked with one another via linear W?N? W nitrido bridges with alternating short and long bonds having average lengths of 166 and 211 pm. The N atoms of the benzonitrile ligands are in the positions trans to the W?N bonds at distances of 237 pm.     

Kristallstruktur von Kaliumtriflat‐Butyrolacton, [K3(O3SCF3)3(O2C4H6)2]

Crystal Structure of Potassium Triflate‐butyrolactone, [K₃(O₃SCF₃)₃(O₂C₄H₆)₂] Single Crystals of [K₃(O₃SCF₃)₃(O₂C₄H₆)₂] ( 1 ) have been obtained as a by‐product from the reaction of KNPPh₃ with Yb(O₃SCF₃)₃ in THF with subsequent addition of butyrolactone. The structure of 1 consists of three symmetry‐independent potassium ions which are linked by the oxygen atoms of the triflate ions and the butyrolactone molecules to give a supramolecular structure with layers normal to the crystallographic b‐axis. The carbonyl oxygen atoms of both butyrolactone molecules show a μ₃‐bridging function between three K⁺ ions, one of them is, in addition, coordinated by the ring O‐atom in a chelate manner. 1 : Space group P2₁/c, Z = 4, lattice dimensions at 193 K: a = 1155.0(1), b = 1537.2(1), c = 1531.1(1) pm, β = 100.623(7)°, R = 0.0484.     

Synthese und Kristallstruktur von Calcium-Kupfer-Diarsenat CaCuAs2O7

Synthesis and Crystal Structure of the Calcium Copper Diarsenate CaCuAs₂O₇ Solid state reactions led to single crystals of CaCuAs₂O₇. X-ray investigations revealed monoclinic symmetry, space group C⁵_2h-P2₁/c, lattice constants a = 7.272(1); b = 8.946(2); c = 9.307(2) Å; β = 109.48(2)°; Z = 4. CaCuAs₂O₇ is characterized by ¹_∞[CaO₆] chains, connected by As₂O₇ double tetrahedra and elongated square CuO₅ pyramids. The hitherto unknown crystal structure shows relationships to CaCuP₂O₇ but not to CaCuV₂O₇.     

Synthese und Kristallstrukturen von (PPh4)2[TeS3] · 2 CH3CN und (PPh4)2[Te(S5)2]

Synthesis and Crystal Structures of (PPh₄)₂[TeS₃] · 2 CH₃CN and (PPh₄)₂[Te(S₅)₂] (PPh₄)₂[TeS₃] · 2 CH₃CN was obtained by the reaction of PPh₄Cl, Na₂S₄ and Te in acetonitrile. With sulfur it reacts yielding (PPh₄)₂[Te(S₅)₂]. The crystal structures of both products were determined by X-ray diffraction. (PPh₄)₂[TeS₃] · 2 CH₃CN: triclinic, space group P1 , Z = 2, R = 0.041 for 4 629 reflexions; it contains trigonal-pyramidal [TeS₃]^2? ions with an average Te? S bond length of 233 pm. (PPh₃)₂[Te(S₅)₂]: monoclinic, P2₁/n, Z = 2, R = 0.037 for 2 341 reflexions. In the [Te(S₅)₂]^2? ion the tellurium atom has a nearly square coordination by four S atoms. Along with the Te atoms each of the two S₅ groups forms a ring with chair conformation.     

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.     

Synthese und Kristallstruktur von [ReNCl(NPPh2C6H4)]2 · [Ph3PNH2]Cl · CH3CN,einem rheniumorganischen Nitrido-Phosphaniminato-Komplex

Synthesis and Crystal Structure of [ReNCl(NPPh₂C₆H₄)]₂ · [Ph₃PNH₂]Cl · CH₃CN, a Rhenium Organic Nitrido Phosphoraneiminato Complex The title compound is synthesized by the reaction of ReNCl₄ with Me₃SiNPPh₃ in boiling acetonitrile, forming colourless crystals, which are characterized by an X-ray structure determination. Space group P1 , Z = 2, 4 037 observed unique reflections, R = 0.043. Lattice dimensions at 19°C: a = 1 005.5; b = 1 695.2; c = 1 744.7 pm, α = 105.86°; β = 101.49°; γ = 104.45°. The structure consists of dimeric molecules [ReNCl(NPPh₂C₆H₄)]₂, triphenylphosphorane ammoniumchloride and included acetonitrile molecules. In the nitrido phosphoraneiminato complex the rhenium atoms are μ₂-bridged via the N-Atoms of the phosphoraneiminato ligands. Because of this bridging and a Re? Re bond, one terminal nitrido ligand, one terminal chloro ligand, and a Re? C bond of an -C-atom of one phenylene group of Re-atoms attain co-ordination number six.     

[Mo(NPPh3)4]2+ [MoNCl3(NPPh3)]2− · C7H8, ein Phosphaniminato-Komplex mit einem Dikation von Molybdän(VI)

[Mo(NPPh₃)₄]²⁺ [MoNCl₃(NPPh₃)]₂^? · C₇H₈, a Phosphoraneiminato Complex with a Dication of Molybdenum(VI). The title compound was prepared by the reaction of MoNCl₃ with Me₃SiNPPh₃ in acetonitrile solution. Red single crystals separated upon addition of toluene. They were characterized by IR spectroscopy and by an X-ray structure determination. (Space group P1 , Z = 2, 6918 observed unique reflections, R = 0.059. Lattice dimensions at 20°C: a = 1 181.4, b = 2 021.4, c =2 409.7pm; α = 65.87°, β = 101.09°, γ= 78.97°). In the dication [Mo(NPPh₃)₄]²⁺ the molybdenum atom is surrounded in a tetrahedral fashion by the four nitrogen atoms of the phosphorane iminato ligands. The MoN and PN bond lengths correspond well with double bonds. In the two anions [MoNCl₃(NPPh₃)]^?, which occur in different conformations, the molybdenum atoms are fivefold coordinated by the terminal nitride ligand Mo?N: in axial positions and by the three chlorine atoms and the nitrogen atom of the (NPPh₃)^? ligand in the equatorial positions.     

Synthese,Struktur und Phasenumwandlung von Te4[AsF6]2·SO2

Synthesis, Crystal Structure, and Solid State Phase Transition of Te₄[AsF₆]₂·SO₂ The oxidation of tellurium with AsF₅ in liquid SO₂ yields Te₄²⁺[AsF₆^—]₂ which can be crystallized from the solution in form of dark red crystals as the SO₂ solvate. The crystals are very sensitive against air and easily lose SO₂, so handling under SO₂ atmosphere or cooling is required. The crystal structure was determined at ambient temperature, at 153 K, and at 98 K. Above 127 K Te₄[AsF₆]₂·SO₂ crystallizes orthorhombic (Pnma, a = 899.2(1), b = 978.79(6), c = 1871.61(1) pm, V = 1647.13(2)·10⁶pm³ at 297 K, Z = 4). The structure consists of square‐planar Te₄²⁺ ions (Te‐Te 266 pm), octahedral [AsF₆]^— ions and of SO₂ molecules which coordinate the Te₄ rings with their O atoms in bridging positions over the edges of the square. At room temperature one of the two crystallographically independent [AsF₆]^— ions shows rotational disorder which on cooling to 153 K is not completely resolved. At 127 K Te₄[AsF₆]₂·SO₂ undergoes a solid state phase transition into a monoclinic structure (P112₁/a, a = 866.17(8), b = 983.93(5), c = 1869.10(6) pm, γ = 96.36(2)°, V = 1554, 2(2)·10⁶ pm³ at 98 K, Z = 4). All [AsF₆]^— ions are ordered in the low temperature form. Despite a direct supergroup‐subgroup relationship exists between the space groups, the phase transition is of first order with discontinuous changes in the lattice parameters. The phase transition is accompanied by crystal twinning. The main difference between the two structures lies in the different coordination of the Te₄²⁺ ion by O and F atoms of neighbored SO₂ and [AsF₆]^— molecules.