Structural Isomers of Bis(diphenylarsino)methane‐dichloroplatinum(II)

From a range of preparative methods, three geometric isomers of bis(diphenylarsino)methane‐dichloroplatinum(II) have been isolated, viz. cis‐PtCl₂(dpam), trans, trans‐Pt₂Cl₄(dpam)₂ and cis, trans‐Pt₂Cl₄(dpam)₂. Their structures were determined by single‐crystal X‐ray diffraction.     

Spin-orbit electronic states of octahedral Pt-group d 6 complexes as derived from reflectance spectra and ligand field calculations

The 90 K diffuse reflectance spectra of some octahedral Rh(III), Ir(III) and Pt(IV) complex compounds with chloride, thiocyanate and amine ligands are reported. The spectra show in the visible and near ultraviolet distinct bands due to spin-orbit components of singlet-triplet d-d transitions which are explained by ligand field calculations including spin-orbit coupling considering all possible d-electron configurations. Model parameter sets are obtained by fitting the measured band peaks to possible transitions between calculated energy levels. For some of the bands the vibrational structure could be resolved which is assigned to metal-ligand stretching vibrations of the electronically excited complex octahedra with vibrational fundamentals lower than those of the ground state.     

Bestimmung einer Phasenumwandlungstemperatur mit der Differentialthermoanalyse

Zusammenfassung Aus dem Maximalwert einer Differentialthermoanalysenkurve kann die Temperatur einer Phasenumwandlung abgeleitet werden. Für die Auswertung benötigt man Kurven, die bei verschiedener Aufheizgeschwindigkeit gemessen wurden. Das Verfahren wurde an K₂SO₄ und BaCO₃ getestet. Die Experimente ergaben 583,3 bzw. 809,6°C.Herrn Prof. Dr. H. Hausner danke ich für die Förderung dieser Arbeit und Frau H. Tyrlas für die umsichtige und sorgfältige Durchführung der Experimente.     

Synthesis and crystal structures of Cd[AlCl4]2 and Cd2[AlCl4]2

Colorless single crystals of Cd[AlCl₄]₂ grow from the melt of CdCl₂ and AlCl₃ upon slow cooling from 250°C. The crystal structure [monoclinic, P1a1, Z = 2, a = 1288.7(2), b = 660.2(1), c = 705.1(1) pm, β = 92.89(1)º] may be derived from hexagonally closest packed layers of Cl^?. Octahedral and tetrahedral holes are filled with Cd²⁺ and Al³⁺ in a 1:2 ratio between all layers stacked in the [104] direction. Cd[GaCl₄]₂ and Cd[AlBr₄]₂ are isotypic. Reduction of Cd[AlCl₄]₂ with excess cadmium shot and slow cooling from 350°C yields plate-like very moisture-sensitive, colorless single crystals of Cd₂[AlCl₄]₂. The crystal structure [triclinic, C1 , Z = 2, a = 655.47(3), b = 1135.26(1), c = 935.23(6) pm, α = 89.70(2)º, β = 103.61(1)º, γ = 90.455(1)º] is built from slabs stacked in the [100] direction consisting of ethane-like [Cd₂Cl₆] units with a Cd? Cd distance of 256.1 pm sharing common vertices with [AlCl₄] tetrahedra.     

Cs3[Tb10(C2)2]Cl21, ein neuer Formel- und Strukturtyp mit isolierten,dimeren Clustern

Cs₃[Tb₁₀(C₂)₂]Cl₂₁, A New Formula and Structure Type with Isolated Dimeric Clusters Cs₃[Tb₁₀(C₂)₂]Cl₂₁ is obtained via the metallothermic reduction of TbCl₃ with caesium in the presence of graphite as black single crystals. The crystal structure (monoclinic, C2/c, Z = 4; a = 2318.72(13); b = 1245.8(9); c = 1502.0(13) pm; β = 98.13(6)°; R = 0.089; R_w = 0.049) contains dimeric clusters that are built from two octahedra connected via one common edge and filled with C₂ units. These isolated [Tb₁₀(C₂)₂] clusters are surrounded by 26 chloride ligands which are then connected via i—a and a—a bridges in a way that voids for Cs⁺ of coordination number 10 are formed.     

Caesium Heptaiodo‐Dititanate(III), CsTi2I7

Caesium heptaiodo‐dititanate(III), CsTi₂I₇, is obtained from CsI, Ti and TiI₄ at 250 °C in a sealed tantalum ampoule as dark red single crystals. The crystal structure (trigonal, R‐3, a = 1706.6(3), c = 2088.3(5) pm, Z = 12, R1 = 0.0619) contains [TiI₄] tetrahedra sharing common vertices (with Ti—I—Ti angles of 180°) to isolated ditetrahedra [Ti₂I₇]^—. It may also be described as a cubic closest packing of alternating CsI₃ and I₄ layers between which neighbouring tetrahedra are occupied in a way that [Ti₂I₇]^— ditetrahedra are achieved. http://www.gerdmeyer.de     

Cs[Er6C]I12 und Cs2Lu[Lu6C]Cl18: Beispiele für quaternäre reduzierte Halogenide der Lanthanide mit isolierten „Clustern”︁

CS[Er₆C]I₁₂ and cs₂Lu[Lu₆C]CI₁₈: Examples for Quaternary Reduced Halides of the Lanthanides with Isolated “Clusters” Cs[Er₆C]I₁₂ and Cs₂Lu[Lu₆C]Cl₁₈ were obtained as byproducts through metallothermic reductions of ErI₃ and LuCl, with cesium in the presence of carbon in sealed tantalum containers at temperatures ranging from 700 to 940 °C. Cs₂Lu[Lu₆C]Cl₁₈ (isostructural with Cs₂Zr[Zr₆H]Cl₁₈, R 3 , a = 981.7 pm, c = 2723.2 pm, Z = 3, R = 0.082, R, = 0.053) contains octahedral [Lu₆C] clusters which are slightly compressed along the threefold axis and edge-bridged by twelve chloride anions to form [Lu₆C]Cl₁₂ units. Six additional Cl in exo positions of the cluster provide octahedral coordination for the seventh Lu³⁺. Cs⁺ occupies anticuboctahedral interstices within the Cl⁺ layers as a part of the (hexagonal) closest packed arrangement. Cs[Er₆C]I₁₂ (trigonal, R 3, a = 1112.0pm, c = 2063.8pm, Z = 3, R = 0.094, R, = 0.068) exhibits [Er₆C]I₁₂ units as well and shows the structural framework of Sc[Sc₆N]Cl₁₂. Instead of Sc³⁺ in octahedral holes, cesium occupies a regular iodide position within the ccp sheets forming [CsI₃] layers. Both halides are compared with other compounds of the lanthanides containing isolated [M₆X₁₂] clusters. The extreme electron deficiency is discussed.     

Selten‐Erd‐Metall‐Koordinationspolymere: Synthesen und Kristallstrukturen von drei neuen Glutaraten, [Pr2(Glu)3(H2O)4] · 10,5H2O, [Pr(Glu)(H2O)2]Cl und [Er(Glu)(GluH)(H2O)2]

Rare‐Earth‐Metal Coordination Polymers: Syntheses and Crystal Structures of Three New Glutarates, [Pr₂(Glu)₃(H₂O)₄] · 10.5H₂O, [Pr(Glu)(H₂O)₂]Cl, and [Er(Glu)(GluH)(H₂O)₂] The new rare‐earth dicarboxylates [Pr₂(Glu)₃(H₂O)₄] · 10.5H₂O ( 1 ), [Pr(Glu)(H₂O)₂]Cl ( 2 ) and [Er(Glu)(GluH)(H₂O)₂] ( 3 ) were obtained from the reactions of glutaric acid with PrCl₃·6H₂O and Er(OH)₃, respectively. The crystal structures were determined by single‐crystal X‐ray diffraction. [Pr₂(Glu)₃(H₂O)₄] · 10,5H₂O crystallizes in the orthorhombic space group Pnma (no. 62) with a = 871.7(4), b = 3105.0(9), c = 1308.3(9) pm and Z = 4. The crystals of [Pr(Glu)(H₂O)₂]Cl are monoclinic (I2/a; no. 15) with a = 786.2(1), b = 1527.6(2) c = 801.2(1) pm, β = 99.78(1)° and Z = 4. [Er(Glu)(GluH)(H₂O)₂] crystallizes in the monoclinic space group P2₁/a (no. 14) with lattice parameters of a = 882.4(1), b = 1375.3(2), c = 1267.4(2) pm, β = 107.13(1)° and Z = 4. The rare‐earth cations have the coordination numbers 10 ( 1 ), 8 + 1 ( 2 ) and 9 ( 3 ). The individual polyhedra are connected to chains and further to sheets in 1 and 2 and to double chains in 3 . Only in the water‐rich compound 1 there are channels that contain crystal water molecules. It, therefore, has a considerably lower density than 2 and 3 .