Wasserstoffbrückenbindungen mit Cyanidionen? Die Strukturen von 1,3‐Diisopropyl‐4,5‐dimethylimidazoliumcyanid und 1‐Isopropyl‐3,4,5‐trimethylimidazoliumcyanid

Hydrogen Bonds with Cyanide Ions? The Structures of 1,3‐Diisopropyl‐4,5‐dimethylimidazolium Cyanide and 1‐Isopropyl‐3,4,5‐trimethylimidazolium Cyanide 1,3‐Diisopropyl‐4,5‐dimethylimidazolium cyanide ( 2a ) and 1‐isopropyl‐3,4,5‐trimethylimidazolium cyanide ( 2b ) are obtained from the reaction of the corresponding 2,3‐dihydrodimethylimidazol‐2‐ylidenes ( 1 ) and hydrogen cyanide in excellent yield. Their crystal structure analyses reveal the presence of ion pairs linked by hydrogen bonds. The crystal structure analysis of 2a reveals a near colinear orientation of the C(1)‐H bond axis and the cyanide ion while in 2b this orientation is perpendicular. In both cases, the interionic distances are in the expected range for hydrogen bonds. Ab‐initio calculations of the total energy of the salts 2 indicate small differences in energy between the colinear and perpendicular orientation of the ions as well as between the colinear C‐H···C‐N and C‐H···N‐C orientations. The comparison of calculated and measured ¹³C and ¹⁵N NMR chemical shifts does not allow the distinction between the possible orientations.     

Kristallstrukturen und chemische Bindung von AM2GeSe4 (A = Sr,Ba; M = Cu,Ag)

New Noncentrosymmetric Selenogermanates. I. Crystal Structures and Chemical Bonding of AM ₂GeSe₄ ( A = Sr, Ba; M = Cu, Ag) Three new quaternary selenogermanates were synthesized by heating the elements at 983–1073 K. Their crystal structures were determined by single crystal X‐ray methods. The dark red semiconductors crystallize in noncentrosymmetric space groups. SrCu₂GeSe₄ (Ama2, a = 10.807(4) Å, b = 10.735(4) Å, c = 6.541(2) Å, Z = 4) forms a new structure type, whereas BaCu₂GeSe₄ (P3₁, a = 6.490(1) Å, c = 16.355(3) Å, Z = 3) and BaAg₂GeSe₄ (I222, a = 7.058(1) Å, b = 7.263(1) Å, c = 8.253(2) Å, Z = 2) crystallize in structures known from thiostannates. Main structural features are almost regular GeSe₄‐, but distorted CuSe₄‐ or AgSe₄‐tetrahedra sharing corners or edges. Eight selenium atoms coordinate the alkaline earth atoms in the voids of these three dimensional tetrahedral networks. Chemical bonding and the electronic structure are elucidated by self‐consistent band structure calculations and the COHP method. The electron density and the electron localization function ELF of SrCu₂GeSe₄ reveal a significant stronger covalent character for the Ge–Se bonds compared with the Cu–Se bonds. For this reason the GeSe₄ tetrahedra appear as quasi molecular entities, arranged spatially according to the motifs of closest packing. The metal atoms occupy the tetrahedral and octahedral voids of these “tetrahedra packing”. This concept allows to derive the structures of AM₂GeSe₄‐compounds from simple binary structure types as Li₃Bi or Ni₂In.     

Kristallstrukturen der Monofluorosulfite MSO2F (M = K,Rb)

Crystal Structures of Monofluorosulfites MSO₂F (M = K, Rb) Single crystals of potassium and rubidium fluorosulfite were obtained for the first time by reacting the alkali metal fluorides with sulfur dioxide in acetonitrile at 75 °C. According to the results of X‐ray structure determinations they are isotypic (monoclinic, P2₁/m, Z = 2, KSO₂F: a = 696.2(2), b = 566.3(2), c = 465.8(1) pm, β = 107.73(2)°, RbSO₂F: a = 717.2(1), b = 586.7(1), c = 484.0(1) pm, β = 107.14(1)°) and structurally analogous to potassium chlorate. In contrast to potassium fluoroselenite in which the complex anions are polymerized to linear chains by unsymmetric fluorine bridges, the fluorosulfite anion is isolated. The S–F‐distance of 159.1(2) pm (KSO₂F) corresponds to a S–F single bond, the S–O‐distance of 152.6(2) pm indicates a bond order of 1.5.     

Die neuen gemischtvalenten Chalkogenoindate MIn7X9 (M = Rb,Cs; X = S,Se): Strukturchemie,Röntgenund HRTEM‐Untersuchungen

The New Mixed Valent Chalcogenoindates MIn₇X₉ (M = Rb, Cs; X = S, Se): Structural Chemistry, X‐Ray and HRTEM Investigations Systematic X‐ray and HRTEM investigations on the ternary systems alkali metal (or thallium)–indium–chalcogen proved the existence of mixed valent solids with the simultaneous occurrence of indium species in different states of oxidation. Additionally to the earlier described solids MIn₅S₇ (M: Na, K, Tl: isotypic to InIn₅S₇ = In₆S₇ and TlIn₅S₇) and KIn₅S₆ (isotyp to TlIn₅S₆) in the actual work we present with MIn₇X₉ (M: Rb, Cs; X: S, Se) a new structure type which also contains indium in the states of oxidation +3 and +2. The formal state of oxidation In²⁺ corresponds to (In₂)⁴⁺ ions. A reasonable ionic formulation of these structures is given by: MIn₅S₇ = M⁺ 3[In³⁺] [(In₂)⁴⁺] 7[S^2–] (M = Na, K, Tl), MIn₅S₆ = M⁺ [In³⁺] 2[(In₂)⁴⁺] 6[S^2–] (M = K, Tl), MIn₇X₉ = M⁺ 3[In³⁺] 2[(In₂)⁴⁺] 9[S^2–]. The three structure types show common two dimensional structure elements which contain ethane analogous In₂X₆ units and cis and trans edge sharing double octahedron chains. The main interest of this work is a crystalchemical discussion taking into account the new compounds MIn₇X₉ and the results of special HRTEM investigations on MIn₇X₉. The HRTEM investigations aim on the identification and subsequent preparation of new phases which initially might be visible as nano size crystals or inclusions in the HRTEM only.     

Einfluss von H‐Brückenbindungen auf die Jahn–Teller‐Verzerrung in den Kettenstrukturen von 2,2′‐bipyMn(H2PO4)F2·H2O und 2,2′‐bipyMn(H2PO4)2F

In the system 2,2′‐bipyridine/Mn^III/HF/H₃PO₄/H₂O two compounds with chain structures could be prepared and characterised by X‐ray structure analyses. 2,2′‐bipyMn(H₂PO₄)F₂·H₂O ( 1 ): monoclinic, twinned, space group P2₁/c, Z = 4, a = 6.7883(4), b = 10.9147(5), c = 17.8102(8) Å, β = 100.142(4)°, R = 0.0328. 2,2′‐bipyMn(H₂PO₄)₂F ( 2 ): triclinic, space group P , Z = 2, a = 6.675(1), b = 10.715(1), c = 11.013(1) Å, α = 107.595(9)°, β = 90.994(9)°, γ = 95.784(8)°, R = 0.0252. Both compounds show chain structures with trans‐bridging dihydrogenphosphate ligands and bipy and two fluorine ligands for ( 1 ), or bipy, fluorine and an additional dihydrogenphosphate, respectively, for ( 2 ) in equatorial positions. Due to the pseudo‐Jahn–Teller effect, Mn^III shows elongated octahedral coordination with ferrodistortive ordering along the chain direction. The distortion is remarkably higher in ( 1 ) than in ( 2 ). This is discussed in context with additional hydrogen bonds along the chain in ( 2 ).     

Quervernetzung lamellarer Schichten mit Hilfe von (O–H…O)‐Wasserstoffbrücken: Strukturen von M⊕⊖N(SO2C6H4‐4‐COOH)2 (M⊕ = K⊕, Rb⊕, Cs⊕)

Structures of Ionic Di(arenesulfonyl)amides. 4. Cross‐Linking Lamellar Layers by O–H…O Hydrogen Bonds: Structures of M^⊕⊖N(SO₂C₆H₄‐4‐COOH)₂ (M^⊕ = K^⊕, Rb^⊕, Cs^⊕) Syntheses and low‐temperature X‐ray crystal structures are reported for M^IN(SO₂C₆H₄‐4‐COOH)₂, where M = K (monoclinic, space group P2₁/c, Z = 4, Z′ = 1), M = Rb (monoclinic, P2₁, Z = 4, Z′ = 2), or M = Cs (monoclinic, P2₁/c, Z = 4, Z′ = 1). The three compounds are examples of layered inorgano‐organic solids where the inorganic component is comprised of metal cations and N(SO₂)₂ groups and the outer regions are formed by the 4‐carboxy substituted phenyl rings of the folded anions. In the two‐dimensional coordination networks, K^⊕ and Cs^⊕ adopt irregular and chemically distinct [MN₁O₇] octacoordinations, whereas the independent Rb^⊕ cations attain irregular nonacoordinations of type [RbN₂O₇] or [RbO₉] respectively. The crystal packings of the compounds are governed by self‐assembly of parallel layers through exhaustive hydrogen bonding between carboxylic acid groups, resulting in a dense array of cyclic (COOH)₂ motifs within the interlamellar regions.     

Ternäre Alkalimetall‐Übergangsmetall‐Acetylide der Zusammensetzung A2MC2 mit A = Rb,Cs und M = Pd,Pt

Ternary Alkali Metal Transition Metal Acetylides A₂MC₂ with A = Rb, Cs, and M = Pd, Pt By the reaction of Rb₂C₂ and Cs₂C₂ with palladium or platinum powder in sealed glass ampoules at 653 K ternary acetylides A₂MC₂ (A = Rb, Cs; M = Pd, Pt) were obtained. Their crystal structures were solved and refined by means of X‐ray powder investigations (Na₂PdC₂ structure type, P 3 m1, Z = 1). The crystal structures are characterised by [M(C₂)_2/2^2–] chains separated by the alkali metals. Raman spectroscopic investigations revealed wave numbers of the C–C stretching vibrations between 1833 and 1842 cm^–1, which are in good agreement with the results of the analogous sodium and potassium compounds.     

IR- und Raman-Spektren der isotypen Iodathydrate M(IO3)2 · 4 H2O (M = Mg,Ni, Co); Kristallstruktur von Co(IO3)2 · 4 H2O

Infrared and Raman Spectroscopy of the Isostructural Iodate Hydrates M(IO₃)₂ · 4 H₂O (M = Mg, Ni, Co)-Crystal Structure of Cobalt Iodate Tetrahydrate The iodate tetrahydrates Mg(IO₃)₂ · 4 H₂O, β-Ni(IO₃)₂ · 4 H₂O, Co(IO₃)₂ · 4 H₂O and their deuterated specimens were studied by X-ray, infrared and Raman spectroscopic methods. The title compounds are isostructural crystallising in the monoclinic space group P2₁/c (Z = 2). The crystal structure of Co(IO₃)₂ · 4 H₂O (a = 836.8(5), b = 656.2(3), c = 850.2(5) pm and β = 100.12(5)°) has been refined by single-crystal X-ray methods (R_obs = 3.08%, 693 unique reflections I₀ > 2σ(I)). Isolated Co(IO₃)₂(H₂O)₄ octahedra form layers parallel (100). Within these layers, the two crystallographically different hydrate water molecules form nearly linear hydrogen bonds to adjacent IO₃^– ions (ν_OD of matrix isolated HDO of Co(IO₃)₂ · 4 H₂O (isotopically diluted samples) 2443 (H3), 2430 (H2), and 2379 cm^–1 (H1 and H4), –180 °C). Intramolecular O–H and intermolecular H…O distances were derived from the novel ν_OD vs. r_OH and the traditional ν_OD vs. r_H…O correlation curves, respectively. The internal modes of the iodate ions of the title compounds are discussed with respect to their coupling with the librations of the hydrate H₂O molecules, the distortion of the IO₃^– ions, and the influence of the lattice potential.     

Synthese und Kristallstruktur von Hydrogenselenaten zweiwertiger Metalle – M(HSeO4)2 (M = Mg,Mn, Zn) und M(HSeO4)2 · H2O (M = Mn,Cd)

Synthesis and Crystal Structure of Hydrogen Selenates of Divalent Metals – M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) New hydrogen selenates M(HSeO₄)₂ (M = Mg, Mn, Zn) and M(HSeO₄)₂ · H₂O (M = Mn, Cd) have been synthesized using MSeO₄ (M = Mg, Mn, Zn, Cd) and 90% selenic acid as starting materials. The crystal structures have been determined by X-ray single crystal crystallography. The compounds M(HSeO₄)₂ (M = Mg, Zn) belong to the structure type of Mg(HSO₄)₂, whereas Mn(HSeO₄)₂ forms a new structure type. Both hydrogen selenate monohydrates are isotypic to Mg(HSO₄)₂ · H₂O. In all compounds the metal atoms are octahedrally coordinated by oxygen atoms of different HSeO₄-tetrahedra. In the HSeO₄-tetrahedra the Se–OH-distances (mean value 1.70 Å) are about 0.1 Å longer than Se–O-distances (mean value 1.62 Å). In the structure of M(HSeO₄)₂ (M = Mg, Zn) there are zigzag chains of hydrogen bonded HSeO₄-tetrahedra. The structure of Mn(HSeO₄)₂ is characterized by chains of HSeO₄-tetrahedra in form of screws. Hydrogen bonds from and to water molecules connect double layers of MO₆-octahedra and HSeO₄-tetrahedra in the structures of M(HSeO₄)₂ · H₂O.     

Alkalimetall‐Oxoantimonate: Synthesen,Kristallstrukturen und Schwingungsspektren von ASbO2 (A = K,Rb), A4Sb2O5 (A = K,Rb, Cs) und Cs3SbO4

Alkaline Metal Oxoantimonates: Synthesis, Crystal Structures, and Vibrational Spectroscopy of ASbO₂ (A = K, Rb), A₄Sb₂O₅ (A = K, Rb, Cs), and Cs₃SbO₄ The compounds ASbO₂ (A = K/Rb; monoclinic, C2/c, a = 785.4(3)/799.6(1) pm, b = 822.1(4)/886.32(7) pm, c = 558.7(3)/559.32(5) pm, β = 124.9(1)/123.37(6)°, Z = 4) are isotypic with CsSbO₂ and the corresponding bismutates. The structures of the antimonates A₄Sb₂O₅ (A = K/Rb: orthorhombic, Cmcm, a = 394.9(1)/407.34(7) pm, b = 1807.4(1)/1893.5(1) pm, c = 636.34(9)/655.60(8) pm, Z = 2) and Cs₄Sb₂O₅ (monoclinic, Cm, a = 1059.81(7) pm, b = 692.68(8) pm, c = 811.5(1) pm, β = 98.7(1)°, Z = 2) both contain the anion [O₂SbOSbO₂]^4–. Cs₃SbO₄ (orthorhombic, Pnma, a = 1296.1(1) pm, b = 919.24(8) pm, c = 679.95(6) pm, Z = 4) crystallizes with the K₃NO₄ structure type.     

Synthese,Kristallstruktur und Eigenschaften der käfigartigen,sechsbasigen Säure P12S12N8(NH)6 · 14 H2O sowie ihrer Salze Li6[P12S12N14] · 26 H2O, (NH4)6[P12S12N14] · 10 H2O und K6[P12S12N14] · 8 H2O

Syntheses, Crystal Structure, and Properties of the Cage‐like, Hexaacidic P₁₂S₁₂N₈(NH)₆ · 14 H₂O and its Salts Li₆[P₁₂S₁₂N₁₄] · 26 H₂O, (NH₄)₆[P₁₂S₁₂N₁₄] · 10 H₂O, and K₆[P₁₂S₁₂N₁₄] · 8 H₂O The cage‐like acid P₁₂S₁₂N₈(NH)₆ · 14 H₂O was obtained by the reaction of KSCN with P₄S₁₀ via the formation of K₆[P₁₂S₁₂N₁₄] · 8 H₂O and subsequent ion exchange reactions in aqueous solution. Starting from the acid the salts Li₆[P₁₂S₁₂N₁₄] · 26 H₂O and (NH₄)₆[P₁₂S₁₂N₁₄] · 10 H₂O were synthesized. According to X‐ray single‐crystal structure analyses the compounds are built up by isosteric P–N cages [P₁₂S₁₂N^[3]₈N^[2]₆]^6–. Each of them is made up of twelve P₃N₃ rings, which exclusively exhibit the boat conformation. The cages have the idealized symmetry 2/m3; P₁₂S₁₂N₈(NH)₆ · 14 H₂O: P1, a = 1119.11(7), b = 1123.61(7), c = 1125.80(6) pm, α = 80.186(4), β = 60.391(4), γ = 60.605(4)°, Z = 1; Li₆[P₁₂S₁₂N₁₄] · 26 H₂O: Fm3, a = 1797.4(1) pm, Z = 4; (NH₄)₆[P₁₂S₁₂N₁₄] · 10 H₂O: P6₃, a = 1153.2(1), c = 2035.6(2) pm, Z = 2; K₆[P₁₂S₁₂N₁₄] · 8 H₂O: R3c, a = 1142.37(5), c = 6009.6(3) pm, Z = 6. In the crystal the cages of the acid are crosslinked via hydrate molecules by hydrogen bonds. The cations in the salts show a high‐mobility and are located between the cages.     

Zwei Tetrachlorothiotantalate: [Na‐15‐Krone‐5][TaSCl4 · Dioxan] und [Na‐15‐Krone‐5]2[(TaSCl4)2Dioxan] · S8

Two Tetrachlorothiotantalates: [Na‐15‐crown‐5][TaSCl₄ · dioxane] and [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ During the reaction of Na₂S₄, TaCl₅ and 15‐crown‐5 in dichloromethane the crown ether partly suffers degradation to 1,4‐dioxane. Aside from sulfur, [Na‐15‐crown‐5][TaSCl₄ · dioxane] was the first product obtained. It crystallizes in the monoclinic space group P2₁/n with a = 1066.1, b = 1781.3, c = 1258.3 pm, β = 97.14°, Z = 4. In the [TaSCl₄ · dioxane]^– ion a dioxane molecule is loosely bonded to a square‐pyramidal TaSCl₄^– unit; two chlorine atoms are in contact with an Na⁺ ion. Upon standing with the mother liquor [Na‐15‐crown‐5]₂[(TaSCl₄)₂dioxane] · S₈ was formed. It crystallizes in the monoclinic space group C2/m; a = 1768.5, b = 1084.0, c = 1517.3 pm, β = 118.46°, Z = 4. In this case a dioxane molecule is coordinated with two TaSCl₄^– units. The [(TaSCl₄)₂ · dioxane]^2– ions and S₈ molecules alternate in the stacking direction b.     

Über die komplexen Hydroxide des Chroms: Na9[Cr(OH)6]2(OH)3 · 6 H2O und Na4[Cr(OH)6]X · H2O (X = Cl, (S2)1/2) – Synthese,Kristallstruktur und thermisches Verhalten

Complex Hydroxides of Chromium: Na₉[Cr(OH)₆]₂(OH)₃ · 6 H₂O and Na₄[Cr(OH)₆]X · H₂O (X = Cl, (S₂)_1/2) – Synthesis, Crystal Structure, and Thermal Behaviour Green plate‐like crystals of Na₉[Cr(OH)₆]₂(OH)₃ · 6 H₂O (triclinic, P1, a = 872.9(1) pm, b = 1142.0(1) pm, c = 1166.0(1) pm, α = 74.27(1)°, β = 87.54(1)°, γ = 70.69(1)°) are obtained upon slow cooling of a hot saturated solution of Cr^III in conc. NaOH (50 wt%) at room temperature. In the presence of chloride or disulfide the reaction yields green prismatic crystals of Na₄[Cr(OH)₆]Cl · H₂O (monoclinic, C2/c, a = 1138.8(2) pm, b = 1360.4(1) pm, c = 583.20(7) pm, β = 105.9(1)°) or green elongated plates of Na₄[Cr(OH)₆](S₂)_1/2 · H₂O (monoclinic, P2₁/c, a = 580.8(1) pm, b = 1366.5(3) pm, c = 1115.0(2) pm, β = 103.71(2)°), respectively. The latter compounds crystallize in related structures. All compounds can be described as distorted cubic closest packings of the anions and the crystal water molecules with the cations occupying octahedral sites in an ordered way. The thermal decomposition of the compounds was investigated by DSC/TG or DTA/TG and high temperature X‐ray powder diffraction measurements. In all cases the final decomposition product is NaCrO₂.     

Orthotelluric Acid as Substitute for Crystal‐Water: Syntheses and Crystal Structure of the Co‐crystallate [Te(OH)6 · 2 Adenine · 4 H2O] and the Disodium Ditellurate(VI) Aggregate {[Te2O2(OH)6(ONa)2]2[NaOH · 12.5 H2O]}

Supramolecular aspects on Te(OH)₆ as substitute for crystal‐water in adenine hydrate complexes and the first disodium ditellurate(VI) are reported. The co‐crystallate [Te(OH)₆ · 2 adenine · 4 H₂O] ( 1 ) has been prepared in 41% yield from the 1 : 1 mixing of Te(OH)₆ with the nitrogenous base adenine. The adduct of infinite stacks of adenine molecules, Te(OH)₆ and water not only proves that Te(OH)₆ mimicks the role of water in the related hydrate adenine · 3 H₂O but also shows that the inclusion of Te(OH)₆ raises the number of HO–H and N–HO contacts and therefore increases the distance between the adenine rings to 3.31 Å in 1 in comparison to that in adenine trihydrate (3.22 Å). Additionally, the disodium ditellurate(VI) aggregate {[Te₂(O)₂(OH)₆(ONa)₂]₂ [NaOH · 12.5 H₂O]} ( 2 ) resulted from the reaction of 1 with 2 molar equivalents of aqueous NaOH. Dinuclear 2 represents the first X‐ray diffraction characterized example of a sodium tellurate(VI) constructed from [Te₂O₄(OH)₆]^2– dianions.     

Zwei neue Iodopalladate mit gleicher Summenformel: Rb2PdI4 · I2 – ein neuer Strukturtyp mit eingelagerten I2‐Molekülen – und Rb2PdI6

Two New Iodopalladates with Identical Chemical Formula: Rb₂PdI₄ · I₂ – a New Structure Type with Insertion of I₂ Molecules – and Rb₂PdI₆ Rb₂PdI₄ · I₂ is the first rubidium iodopalladate(II) which could be prepared. Despite showing the same formula type, the compound is not isotypic to Cs₂PdI₄ · I₂. The crystal structure of Rb₂PdI₄ · I₂ was explored by X‐ray crystal structure analysis. Rb₂PdI₄ · I₂ shows orthorhombic symmetry, space group Pnma (No. 62) with lattice parameters a = 7.982(1) Å, b = 12.267(1) Å, c = 14.599(1) Å, Z = 4. Palladium is coordinated by four iodine atoms building the typical square‐planar coordination. Further iodine is inserted as I₂ molecules. Another compound with the same empirical formula but octahedrally coordinated Pd^IV – Rb₂PdI₆ – could be obtained microcrystallinic in connection with Rb₂PdI₄ · I₂.     

Kristallstruktur,Infrarot‐ und Ramanspektren von Kupfertrihydrogenperiodatmonohydrat,CuH3IO6 · H2O

Crystal Structure, Infrared and Raman Spectra of Copper Trihydrogenperiodate Monohydrate, CuH₃IO₆ · H₂O The hitherto unknown compound CuH₃IO₆ · H₂O was studied by X‐ray, IR‐ and Raman spectroscopic methods. The crystal structure was determined by X‐ray single‐crystal studies (space group P2₁2₁2₁, Z = 4, a = 532.60(10), b = 624.00(10), c = 1570.8(3) pm, R1 = 1.85%, 1559 unique reflections (I > 2σ(I))). Isolated, meridionally configurated H₃IO₆^2– ions are coordinated to the copper ions forming double‐ropes in [100]. These ropes are connected in [010] and [001] by hydrogen bonds. The copper ions possess a square pyramidal co‐ordination with the hydrate H₂O on top. The infrared and Raman spectra as well as group theoretical treatment are presented and discussed with respect to the strength of the hydrogen bonds and the co‐ordination of the CuO₅₍₊₁₎ polyhedra and the H₃IO₆^2– ions at the C₁ lattice sites. The hydrogen bonds of the H₂O molecules and H₃IO₆^2– ions (HO–H…O–IO₅H₃ and H₂IO₅O–H…O–IO₅H₃) greatly differ in strength, as shown from both the respective O…O distances: 282.6 and 298.6 pm (H₂O), and 258.8, 259.7, and 270.9 pm (H₃IO₆^2–) and the OD stretching modes of isotopically dilute samples: 2498 and 2564 cm^–1 (90 K) (HDO), and 1786, 2024, and 2188 cm^–1 (H₂DIO₆^2–). The IO stretching modes of the H₃IO₆^2– ions (696–788 cm^–1 and 555–658 cm^–1, 295 K) display the different strength of the respective I–O and I–O(H) bonds (r_I–O: 181.1–188.3 pm and 189.2–194.5 pm).     

Darstellung,Kristallstruktur und IR‐Spektren von BeSeO3 · H2O – Wasserstoffbrücken und Korrelation von IR‐ und Strukturdaten in den Monohydraten MSeO3 · H2O (M = Be,Ca, Mn,Co, Ni,Zn, Cd)

Preparation, Crystal Structure and IR Spectra of BeSeO₃ · H₂O – Hydrogen Bonds and Correlation of IR and Structure Data in the Monohydrates MSeO₃ · H₂O (M = Be, Ca, Mn, Co, Ni, Zn, Cd) BeSeO₃ · H₂O (oP32) has been obtained by treating amorphous BeSeO₃ · 4 H₂O precipitated from Be(HSeO₃)₂ solutions hydrothermally at 150 °C. The crystal structure (P2₁2₁2₁, a = 560.59(4), b = 755.25(5), c = 781.14(5) pm, Z = 4, D_X = 3.092 gcm^–3, R = 0.018 for the 2034 reflections with I > 2σ_I of the enantiomer investigated) contains BeO₃(H₂O) tetrahedra built up from three selenite and one water oxygen atoms. The BeO₃(H₂O) tetrahedra are 3 D‐connected via Se atoms of trigonal pyramidal SeO₃^2– ions. The Be–O distances are 161.8 to 164.4 pm. The Se–O bond lenghts (169.2–170.3 pm) and the O–Se–O bond angles (98.1–101.4°) are normal. The water molecules of crystallization form together with the SeO₃^2– ions screw‐like hydrogen bond systems along [100]. Despite the strong synergetic effect of the Be²⁺ ions, the hydrogen bonds (d(OH…O) = 267.4 and 276.4 pm, respectively; ν_OD of matrix isolated HDO molecules: 2244 and 2405 cm^–1, respectively) are normal compared to other neutral selenite hydrates. Together with the hitherto known monohydrates M^IISeO₃ · H₂O and other beryllium salt hydrates, the hydrogen bonds of BeSeO₃ · H₂O are discussed with regard to their geometry and IR spectroscopy.     

Darstellung und Struktur der Komplexverbindungen trans‐[CoIII(py)4F2][H2F3] und [Pd(py)4]F2 · 1,5 HF · 2 H2O

Synthesis and Crystal Structures of the Complexes trans ‐[Co^III(py)₄F₂][H₂F₃] and [Pd(py)₄]F₂ · 1.5 HF · 2 H₂O The cobalt complex trans‐[Co(III)(py)₄F₂][H₂F₃] ( 1 ) has been prepared by electrochemical oxidation of CoF₂ in a pyridine/HF mixture and the palladium complex [Pd(py)₄]F₂ · 1.5 HF · 2 H₂O ( 2 ) has been obtained via halogen exchange between Pd(py)₂Cl₂ and AgF₂ in pyridine. 1 and 2 crystallize in the space group C2/c with a = 27.928(14), b = 9.019(3), c = 18.335(8) Å, β = 113.41(3)° for 1 and a = 28.183(9), b = 9.399(3), c = 17.397(6) Å, β = 104.66(3)° for 2 , respectively. Concerning the shape and location of the M(py)₄ fragments 1 and 2 are isostructural. The metal atoms occupy special positions in their unit cells with the result that four complex atoms have C₂ symmetry and four complex cations have C_i symmetry giving a total of Z = 8. In 1 two F^– ions complete an octahedral coordination around the Co atoms (Co–F 1.820(2) to 1.834(3) Å). In 2 the shortest Pd–F distance is 3.031(2) Å. This precludes the existence of Pd–F bonds. In 1 one can identify H₂F₃^– groups. In 2 there are larger aggregates, consisting of F^–, HF, and H₂O subunits, connected by H‐bridges. In spite of these differences, both complexes belong to the same type of structure, which may be of a common type M^x+(py)₄F_x · y HF · z H₂O.     

Synthese,Kristallstrukturen und thermisches Verhalten von Er2(SO4)3 · 8 H2O und Er2(SO4)3 · 4 H2O

Syntheses, Crystal Structures, and Thermal Behavior of Er₂(SO₄)₃ · 8 H₂O and Er₂(SO₄)₃ · 4 H₂O Evaporation of aqueous solutions of Er₂(SO₄)₃ yields light pink single crystals of Er₂(SO₄)₃ · 8 H₂O. X-ray single crystal investigations show that the compound crystallizes monoclinically (C2/c, Z = 8, a = 1346.1(3), b = 667.21(1), c = 1816.2(6) pm, β = 101.90(3)°, R_all = 0.0169) with eightfold coordination of Er³⁺, according to Er(SO₄)₄(H₂O)₄. DSC- and temperature dependent X-ray powder investigations show that the decomposition of the hydrate follows a two step mechanism, firstly yielding Er₂(SO₄)₃ · 3 H₂O and finally Er₂(SO₄)₃. Attempts to synthesize Er₂(SO₄)₃ · 3 H₂O led to another hydrate, Er₂(SO₄)₃ · 4 H₂O. There are two crystallographically different Er³⁺ ions in the triclinic structure (P 1, Z = 2, a = 663.5(2), b = 905.5(2), c = 1046.5(2) pm, α = 93.59(3)°, β = 107.18(2)°, γ = 99.12(3)°, R_all = 0.0248). Er(1)³⁺ is coordinated by five SO₄^2– groups and three H₂O molecules, Er(2)³⁺ is surrounded by six SO₄^2– groups and one H₂O molecule. The thermal decomposition of the tetrahydrate yields Er₂(SO₄)₃ in a one step process. In both cases the dehydration produces the anhydrous sulfate in a modification different from the one known so far.     

Pyridin‐Komplexe von Seltenerd‐Trichloriden. Synthese und Kristallstrukturen von [YCl3(Py)4] und [LnCl3(Py)4] · 0,5 Py mit Ln = La und Er

Pyridine Complexes of Rare Earth Element Trichlorides. Syntheses and Crystal Structures of [YCl₃(py)₄] and [LnCl₃(py)₄] · 0.5 py with Ln = La and Er The pyridine complexes [YCl₃(py)₄] ( 1 ), [LaCl₃(py)₄] · 0.5 py ( 2 · 0.5 py), and [ErCl₃(py)₄] · 0.5 py ( 3 · 0.5 py) have been prepared from the diacetone‐alcohol complexes [LnCl₃(DAA)₂] or directly from the metal trichlorides with excess pyridine to give colourless, only sparingly moisture sensitive crystals. They were characterized by IR spectroscopy and by crystal structure determinations. 1 : Space group Pbca, Z = 16, lattice dimensions at –80 °C: a = 1647.4(1), b = 1743.1(1), c = 3190.5(1) pm, R₁ = 0.031. 2 · 0,5 Py: Space group P2₁/n, Z = 4, lattice dimensions at –80 °C: a = 978.9(1), b = 1704.5(1), c = 1589.5(1) pm, β = 103.61(1)°, R₁ = 0.0281. 3 · 0,5 Py: Space group P2₁/n, Z = 4, lattice dimensions at –80 °C: a = 970.1(1), b = 1706.4(1), c = 1566.1(1) pm, β = 103.46(1)°, R₁ = 0.0232. All complexes realize monomeric molecular structures with the metal atom in a distorted pentagonal‐bipyramidal coordination. One of the chlorine atoms and the four pyridine molecules are in the equatorial plane.