Zur Kristallchemie der Oxoaurate

On the Crystal Chemistry of Oxoaurates The chemistry of oxoaurates is roughly 50 years old. The pioneering work of Rudolf Hoppe and coworkers on alkaline oxoaurates in the 60^ies of the past century and his activities up to the late 90^ies initiate the synthesis of more compounds. The following review systematize the oxoaurates(III) and oxoaurates(I) with respect to pattern of connections of square planar AuO₄ polygones, and dumbbell‐like O—Au—O‐coordinations. The exotic oxides M₃AuO, containing anionic gold (Au^—), will be discussed as antitype of the cubic BaTiO₃. Topics of systematics of oxoaurates(III) are isolated AuO₄ polygones and Au₂O₆groups, [AuO₃]‐ and [AuO₂]‐chains, [Au₂O₅]‐double chains, three dimensional networks and mixed coordinations. The Oxoaurates(I) show O—Au—O dumbbells, closed Au₄O₄ groups and [AuO] chains. Especially the polyhedra of cationic‐rich compounds suffer from the oxygen deficit. In order to define the coordination number of these metal ions calculations of effective coordination numbers (ECoN) created by Hoppe are useful. At least in a special chapter on hypothetical oxoaurates the MAPLE method (calculations of Coulomb‐terms of lattice energy, developed by Hoppe too) has been expanded for the first time to look for additional unknown atomic positions.     

Beiträge zur Kristallchemie und zum thermischen Verhalten von wasserfreien Phosphaten. XXXIII [1] In2P2O7, ein Indium(I)‐diphosphato‐indat(III) und In4(P2O7)3 — Darstellung,Kristallisation und Kristallstrukturen

Contributions on Crystal Chemistry and Thermal Behaviour of Anhydrous Phosphates. XXXIII [1] In₂P₂O₇ an Indium(I)‐diphosphatoindate(III), and In₄(P₂O₇)₃ — Synthesis, Crystallization, and Crystal Structure Solid state reactions via the gas phase lead to the new mixed‐valence indium(I, III)‐diphosphate In₂P₂O₇. Colourless single crystals of In₂P₂O₇ have been grown by isothermal heating of stoichiometric amounts of InPO₄ and InP (800 °C; 7d) using iodine as mineralizer. The structure of In₂P₂O₇ [P2₁/c, a = 7.550(1) Å, b = 10.412(1) Å, c = 8.461(2) Å, b = 105.82(1)°, 2813 independent reflections, 101 parameter, R1 = 0.031, wR2 = 0.078] is the first example for an In⁺ cation in pure oxygen coordination. Observed distances d(In^I‐O) are exceptionally long (d_min(In^I‐O) = 2.82 Å) and support assumption of mainly s‐character for the lone‐pair at the In⁺ ion. Single crystals of In₄(P₂O₇)₃ were grown by chemical vapour transport experiments in a temperature gradient (1000 → 900 °C) using P/I mixtures as transport agent. In contrast to the isostructural diphosphates M₄(P₂O₇)₃ (M = V, Cr, Fe) monoclinic instead of orthorhombic symmetry has been found for In₄(P₂O₇)₃ [P2₁/a, a = 13.248(3) Å, b = 9.758(1) Å, c = 13.442(2) Å, b = 108.94(1)°, 7221 independent reflexes, 281 parameter, R1 = 0.027, wR2 = 0.067].     

Pr4(SeO3)2(SeO4)F6 und NaSm(SeO3)(SeO4): Selenit‐Selenate der Selten‐Erd‐Elemente

Pr₄(SeO₃)₂(SeO₄)F₆ and NaSm(SeO₃)(SeO₄): Selenite‐Selenates of Rare Earth Elements Light green single crystals of Pr₄(SeO₃)₂(SeO₄)F₆ have been obtained from the decomposition of Pr₂(SeO₄)₃ in the presence of LiF in a gold ampoule. The monoclinic compound (C2/c, Z = 4, a = 2230.5(3), b = 710.54(9), c = 835.6(1) pm, β = 98.05(2)°, R_all = 0.0341) contains two crystallographically different Pr³⁺ ions. Pr(1)³⁺ is attached by six fluoride ions and two chelating SeO₃^2– groups (CN = 10), Pr(2)³⁺ is surrounded by four fluoride ions, three monodentate SeO₃^2– and two SeO₄^2– groups. One of the latter acts as a chelating ligand, so the CN of Pr(2)³⁺ is 10. The selenite ions are themselves coordinated by five and the selenate ions by four Pr³⁺ ions. The coordination number of the F^– ions is three and four, respectively. The linkage of the coordination polyhedra leads to cavities in the crystal structure which incorporate the lone pairs of the selenite ions. The reaction of Sm₂(SeO₄)₃ and NaCl in gold ampoules yielded light yellow single crystals of NaSm(SeO₃)(SeO₄). The monoclinic compound (P2₁/c, Z = 4, a = 1066.9(2), b = 691.66(8), c = 825.88(9) pm, β = 91.00(2)°, R_all = 0.0530) contains tenfold oxygen coordinated Sm³⁺ ions. The oxygen atoms belong to five SeO₃^2– and two SeO₄^2– ions. Two of the SeO₃^2– groups as well as one of the SeO₄^2– groups act as a chelating ligand. The sodium ions are surrounded by five SeO₄^2– ions and one SeO₃^2– group. One of the selenate ions is attached chelating leading to a coordination number of seven. Each selenite group is coordinated by six (5 × Sm³⁺ and 1 × Na⁺), each selenate ion by seven cations (5 × Na⁺ and 2 × Sm³⁺).     

Die Kristallstrukturen der Azido‐Platinate (AsPh4)2[Pt(N3)4] und (AsPh4)2[Pt(N3)6]

Crystal Structures of the Azido Platinates (AsPh₄)₂[Pt(N₃)₄] and (AsPh₄)₂[Pt(N₃)₆] The crystal structures of the two homoleptic azido platinates (AsPh₄)₂[Pt(N₃)₄] ( 1 ) and (AsPh₄)₂[Pt(N₃)₆] ( 2 ) were determined by X‐ray diffraction at single crystals. In 1 the [Pt(N₃)₄]^2– ions are without crystallographic site‐symmetry, and the platinum atoms show a planar surrounding. The [Pt(N₃)₆]^2– ions in 2 are centrosymmetric (C_i) with an octahedral surrounding at the platinum atoms. While 1 is highly explosive, 2 is of significantly greater stability. This behaviour is explained by the packing conditions. 1 : Space group P2₁/n, Z = 6, lattice dimensions at –80 °C: a = 1045.3(1), b = 1620.2(1), c = 4041.0(3) pm; β = 96.70(1)°; R₁ = 0.0654. 2 : Space group P1, Z = 1, lattice dimenstions at –80 °C: a = 1027.6(1), b = 1049.1(2), c = 1249.9(3) pm; α = 88.27(1)°, β = 74.13(1)°, γ = 67.90(1)°; R₁ = 0.0417.     

Synthesis and structural characterization of a new two-dimensional polymeric thallium(I) compound, {Tl[(H)phthalate)]} n

A two-dimensional polymer, {Tl[(H)phthalate)]} _n , has been synthesized and characterized by elemental analysis, IR-, ¹H NMR- and ¹³C NMR spectroscopy. The single-crystal X-ray data show the coordination number Tl^I ion is six, TlO₆. However, the arrangement of O-atoms suggests a gap or hole in the coordination geometry around thallium. A stereo chemically ‘active’ electron lone pair of Tl^I possibly occupies this ‘hole’.     

A group of new selenite-chlorides of strontium and d-metals (Co,Ni): Synthesis, thermal behavior and crystal chemistry

The new selenite-chlorides with composition Sr₃(SeO₃)₂Cl₂ (I) and Sr₂M(SeO₃)₂Cl₂ (M=Co, Ni (II and III)) were obtained. They crystallize in monoclinic system I: space group C2/m, a=13.203(2) Å, b=5.5355(8) Å, c=6.6170(10) Å, β=95.89(1)°, Z=2; II Space group P2₁/n, a=5.3400(10) Å, b =6.4279(6) Å, c=12.322(1) Å, β=92.44(1)°, Z=2; III: space group P2₁/n, a=5.3254(11) Å, b=6.4363(13) Å, c=12.197(2), β=92.53(3)°, Z=2. All three compounds are constructed in the same manner. Sr polyhedra form infinite layers, which are interconnected into a 3D framework by means of Sr polyhedra in the case of I or Co and Ni polyhedra in the case of II and III. Se atoms are situated inside the channels of the 3D framework. The topological analysis of ELF for I confirmed that the lone electron pairs of SeO₃ groups are located inside these channels.     

LaPt2Ge2 und EuPt2Ge2 – Neubestimmung der Kristallstrukturen

LaPt₂Ge₂ and EuPt₂Ge₂ – Revision of the Crystal Structures LaPt₂Ge₂ was rechecked by single crystal X‐ray methods resulting in space group P2₁/c (in place of P2₁) and the lattice constants a = 9.953(3), b = 4.439(1), c = 8.879Å, β = 90.62(4)°, and Z = 4. In contrast to previous reports the cell volume had to be doubled. The same is true for EuPt₂Ge₂ (a = 9.731(1), b = 4.446(1), c = 8.823(1) Å, β = 91.26(1)°). The crystal structures correspond to a monoclinic variant of the tetragonal CaBe₂Ge₂ type, whereas the distortion can be described as different rotations of the coordination polyhedra around the La and Eu atoms, respectively. It is most likely that the compounds APt₂Ge₂ with A = Ca, Y, La‐Dy undergo phase transitions at higher temperatures forming then the undistorted CaBe₂Ge₂ type, space group P4/nmm. This was confirmed for SmPt₂Ge₂ (a = 4.292(1), c = 9.980(1) Å; Z = 2) and might also be the case for APt₂Ge₂ with A = Ca, Nd, Sm, Eu, and Gd.     

Strontium–copper selenite–chlorides: Synthesis and structural investigation

Two new complex selenite–chlorides of strontium and copper Sr₂Cu(SeO₃)₂Cl₂ (I) and SrCu₂(SeO₃)₂Cl₂ (II) were obtained and characterized by X-ray diffraction technique, DTA and IR spectroscopy. Both compounds crystallize in the monoclinic system I: Sp. gr. P2₁/n, a=5.22996(3) Å, b=6.50528(4) Å, c=12.34518(7) Å, β=91.3643(2)°, Z=2; II: Sp. gr. P2₁, a=7.1630(14) Å, b=7.2070(14) Å, c=8.0430(16) Å, β=95.92(3)°, Z=2. Comparison of the crystal structure of (I) with the structures of Sr₂M(SeO₃)₂Cl₂ (M=Co, Ni) was performed. The substitution of strontium atom in the structure of (I) by Cu²⁺ ion with a 3d⁹ Jahn–Teller distorted surrounding leads to the lowering of the structure symmetry and to the appearance of the noncentrosymmetric structure of (II). The noncentrosymmetric character of the structure of (II) was confirmed by SHG signal (1.2 units relative to an α-quartz powder sample).     

Preparation and crystal structure of a new bismuth chromate: Bi8(CrO4)O11

Single crystals of a new bismuth chromate, Bi₈(CrO₄)O₁₁, were prepared by hydrothermal reaction of NaBiO₃·nH₂O in K₂CrO₄ solution. The bismuth chromate crystallizes in the monoclinic space group P2₁/m with a=9.657(3), b=11.934(3), c=13.868(2)Å and β=104.14(1)°, Z=4 and the final R factors are R=0.038 and R_w=0.041 for 3541 unique reflections. The crystal structure has a slab built up by (CrO₄)²⁻ tetrahedra and distorted bismuth polyhedra which are five-fold pyramids, six-fold trigonal prisms and octahedra. The distance of lone pair from nucleus for bismuth atoms ranges from 0.29 to 1.12 Å, depending on the coordination environment. Bi₈(CrO₄)O₁₁ decomposes to Bi₁₄CrO₂₄ and a small amount of an unknown phase at 796 °C.     

Kristallographische Gruppe-Untergruppe-Beziehungen und ihre Anwendung in der Kristallchemie

Crystallographic Group-subgroup Relations and their Use in Crystal Chemistry Family trees of crystallographic group-subgroup relations are especially suited to display relationships among crystal structure types. Starting from an aristotype, a simple, highly symmetrical structure type, more and more complicated structures are obtained by reducing the space group symmetry. In doing so, it is important to keep trace of how the occupied Wyckoff positions develop from a space group to its subgroups and which coordinate transformations and origin shifts occur. The neccessary information can by obtained from the new volume A1 of International Tables for Crystallography. Possible error sources are demonstrated with the aid of examples. When a Wyckoff position is split into different symmetry-independent Wyckoff positions, substitution derivatives become possible. If the position does not split, its site symmetry must be reduced, thus rendering possible distorted derivative structures. Such distortions are of special importance in phase transitions, as shown with the examples K₂[TeBr₆], (NO)₂[TiCl₆] and SrCu₂(BO₃)₂. Phase transitions involving a symmetry reduction are likely to produce twinned crystals. This can be the cause of errors in crystal structure determinations, as shown with the example of CaMnF₅. The possible ways to occupy voids in sphere packings can be followed and calculated systematically, including the possibility to predict crystal structures. Sometimes the indices of the symmetry reduction take values that seem curious, such as 13 for CZr₆I₁₂ and 37 for PtCl₃. The systematic application is also possible to molecular packings, such as to the modifications of P₄S₃. Tetraphenylphosphonium salts often crystallize in the space group P4/n or its subgroups, retaining pseudotetragonal symmetry even in monoclinic and triclinic structures.     

Wasserfreie Selenite des Lanthans: Synthese und Kristallstruktur von La2(SeO3)3 und LaFSeO3

Anhydrous Selenites of Lanthanum: Syntheses and Crystal Structures of La₂(SeO₃)₃ and LaFSeO₃ Colorless single crystals of La₂(SeO₃)₃ were obtained via the decomposition of La₂(SeO₄)₃ in the presence of NaCl in sealed gold ampoules. The compound crystallizes in the orthorhombic system (Pnma, Z = 4, a = 846.7(1), b = 1428.6(1), c = 710.3(2) pm, R_all = 0.0223) and contains La³⁺ in tenfold coordination of oxygen atoms which belong to seven SeO₃^2– groups. Hence, three of the latter act as bidentate ligands. The reaction of LiF with La₂(SeO₄)₃ in sealed gold ampoules yielded colorless single crystals of LaFSeO₃ (monoclinic, P2₁/c, Z = 12, a = 1819.8(3), b = 715.75(8), c = 846.4(1) pm, β = 96.89(2)°, R_all = 0.0352). The crystal structure contains three crystallographically different La³⁺ ions. La1 is surrounded by six oxygen atoms from five SeO₃^2– groups and four fluoride ions, La2 is coordinated by two bidentate SeO₃^2– ions and seven fluoride ligands. La3 is surrounded by oxygen atoms only with the coordination number and polyhedron being almost the same as found for La³⁺ in La₂(SeO₃)₃. Furthermore, the crystal structures of both compounds are strongly influenced by the lone pairs of the SeO₃^2– groups.     

Syntheses, crystal structure and spectroscopic characterization of new platinum(II) dithiocarbimato complexes

The reaction of 4-iodobenzenesulfonamide or 4-fluorobenzenesulfonamide with CS₂ and KOH in dimethylformamide yielded the potassium N-R-sulfonyldithiocarbimates, K₂(RSO₂NCS₂) [R = 4-IC₆H₄ (1) and 4-FC₆H₄ (2)]. These salts reacted with K₂[PtCl₄] in water/methanol to yield complex anions bis(N-R-sulfonyldithiocarbimato)platinate(II), which were isolated as their tetrabutylammonium salts, (Bu₄N)₂[Pt(RSO₂NCS₂)₂] [R = 4-IC₆H₄ (3) and 4-FC₆H₄ (4)]. The structures of 2–4 were determined by X-ray crystallography. The Pt²⁺ in both complexes 3 and 4 lies at the inversion centre and the PtS₄ moiety has a distorted square-planar configuration. The compounds were also characterized by IR, ¹H NMR and ¹³C NMR spectroscopies, and elemental analyses. The molar conductance data are consistent with the fact that 3 and 4 are dianionic complexes.     

Crystal structure and magnetic properties of the coupled spin dimer compound SrCu2(TeO3)2Cl2

Single crystals of the strontium copper tellurium oxochloride SrCu₂(TeO₃)₂Cl₂ were synthesized via solid-gas reactions in sealed evacuated silica tubes. The compound crystallizes in the monoclinic system, space group P2₁, a=7.215(2), b=7.2759(15), c=8.239(2) Å, β=96.56(4)°, Z=2. The building units are [SrO₆Cl₂] irregular polyhedra, [CuO₄] and [CuO₃Cl] square planes, [TeO₃E] tetrahedra and [TeO₃₊₁E] trigonal bipyramids; E being the 5s² lone pair of Te(IV). The Cu atoms can be regarded as forming a chain of weakly connected dimers. The magnetic susceptibility of the compound shows a broad maximum typical for antiferromagnetic spin fluctuations with a non-magnetic ground state. A Heisenberg spin model with coupled s=1/2 dimers leads to a satisfactory fitting of the experimental data.