Synthesis and Characterization of Gd2[Pt2(SO4)4(HSO4)2](HSO4)2

Red single crystals of Gd₂[Pt₂(SO₄)₄(HSO₄)₂](HSO₄)₂ (triclinic, , Z = 1, a = 844.02(9), b = 908.50(9), c = 939.49(8) pm, α = 107.73(1)°, β = 112.10(1)°, γ = 103.53(1)°) were obtained by the reaction of [Gd(NO₃)(H₂O)₇][PtCl₆]·4H₂O with sulfuric acid at 320 °C in a sealed glass ampoule. In the crystal structure, Pt₂ dumbbells are coordinated by four chelating sulfate groups and two monodentate hydrogensulfate ions. Two further HSO₄^? ions are not bonded to the Pt₂ dumbbell. The Gd³⁺ ions are eightfold coordinated by oxygen atoms. The IR data of Gd₂[Pt₂(SO₄)₄(HSO₄)₂](HSO₄)₂ are typical for these type of compounds. The thermal decomposition of the compound leads to elemental platinum and Gd₂O₃.     

Hexachloroplatinates of the Lanthanides: Syntheses and Thermal Decomposition of [M(NO3)2(H2O)6]2[PtCl6]·2H2O (M = La,Pr) and [M(NO3)(H2O)7][PtCl6]·4H2O (M = Gd,Dy)

The reaction of the nitrates M(NO₃)₃·6H₂O (M = La, Pr) and (H₃O)₂PtCl₆ led to yellow single crystals of [M(NO₃)₂(H₂O)₆]₂[PtCl₆]·2H₂O (M = La, Pr) (monoclinic, P2₁/c, Z = 2, La/Pr: a = 697.4(3)/695.5(1), b = 1654.5(1)/1652.5(2), c = 1317.7(6)/1318.5(3) pm, β = 93.97°(7)/93.93°(2), R_all = 0.0169/0.0659) while the reaction of M(NO₃)₃·5H₂O (M = Gd, Dy) and (H₃O)₂PtCl₆ yielded yellow single crystals of [M(NO₃)(H₂O)₇][PtCl₆]·4H₂O (monoclinic, P2₁/n, Z = 4, Gd/Dy: a = 838.72(3)/838.40(2), b = 2131.98(6)/2139.50(7), c = 1142.63(3)/1143.10(3) pm, β = 95.670(4)/95.698(3), R_all = 0.0475/0.0337). The crystal structures consist of octahedral [PtCl₆]^2? anions and complex [M(NO₃)₂(H₂O)₆]₂⁺ and [M(NO₃)(H₂O)₇]²⁺ cations, respectively. The thermal decomposition of both types of compounds leads via various steps to elemental platinum and the oxide chlorides MOCl (M = La, Pr, Gd, Dy).     

The Oxidation of ReCl5 with Oleum: Synthesis and Crystal Structure of Re2O4Cl4(SO4)

The reaction of ReCl₅ and fuming sulfuric acid (25 % SO₃) in a sealed glass tube at 200 °C led to red, needle shaped single crystals of Re₂O₄Cl₄(SO₄) (monoclinic, C2/c, a = 1501.8(2) pm, b = 1545.9(2) pm, c = 945.18(8) pm, β = 98.761(9)°, Z = 8). In the crystal structure the [ReO₂] moieties are linked by [SO₄]^2– tetrahedra to chains along the [101] direction. Each sulfate ion connects four rhenium atoms, additional two chloride ions complete the octahedral coordination sphere of each rhenium atom according to $\rm^1_\infty$ [ReO_2/1Cl_2/1(SO₄)_2/4].     

The [Au(CH3SO3)4]– Anion in the Crystal Structures of M[Au(CH3SO3)4] (M = Li,Na, Rb)

The reactions of Au(OH)₃, M₂CO₃ (M = Li, Na, Rb), and methanesulfonic acid at elevated temperatures in sealed glass ampoules lead to single crystals of M[Au(CH₃SO₃)₄] (M = Li, Na, Rb). In the crystal structures of Li[Au(CH₃SO₃)₄] (tetragonal, I$\bar{4}$ , Z = 2,a = 938.64(2) pm, c = 917.01(3) pm, V = 807.93(4) ų) and Rb[Au(CH₃SO₃)₄] (tetragonal, P$\bar{4}$ 2₁c, Z = 2, a = 946.7(1) pm,c = 889.9(1) pm, V = 797.6(2) ų) the complex aurate anions are linked by the M⁺ ions in three dimensions. Contrastingly, in the structure of Na[Au(CH₃SO₃)₄] (triclinic, P$\bar{4}$ , Z = 1, a = 540.04(2) pm,b = 863.75(2) pm, c = 973.29(3) pm, α = 72.694(2)°, β = 75.605(2)°, γ = 77.687(2)°, V = 415.05(2) ų) the complex anions are connected into layers that are further connected by weak hydrogen bonds. The thermal decomposition of Li[Au(CH₃SO₃)₄] was monitored up to 500 °C and leads in a multi‐step process to elemental gold and Li₂SO₄.     

Optical characterization and crystal structure of the novel bronzetype CaxBa1‐xNb2O6 (x = 0.28; CBN‐28)

Calcium barium niobate (CBN), also like strontium barium niobate (SBN), belongs to the materials family of partially filled tetragonal tungsten bronzes, which show relaxor‐type ferroelectric phase transitions and large electro‐optic effects. For the first time, it was possible to grow large single crystals of Ca_0.25Ba_0.75Nb₂O₆ (CBN‐25) and CBN‐28 by using different growing techniques. The successful single crystal growth allowed to investigate several physical properties of the novel phase. Herein, we report on measurements of differential thermal analysis (DTA), wavelength dispersion of the refractive indices, temperature dependence of the birefringence and light absorption. Additionally, results of the single crystal X‐ray structure analysis are presented.     

Hydrogenselenate der Selten‐Erd‐Elemente: Synthese und Kristallstruktur von La(HSeO4)3 und Gd(HSeO4)(SeO4)

Hydrogenselenates of Rare Earth Elements: Syntheses and Crystal Structures of La(HSeO₄)₃ and Gd(HSeO₄)(SeO₄) Colorless transparent single crystals of La(HSeO₄)₃ (hexagonal, P6₃/m, Z = 2, a = 971.7(1), c = 616.98(8) pm, R_all = 0.0440) were obtained from the reaction of La₂O₃ and conc. selenic acid. La(HSeO₄)₃ is isotypic with the corresponding hydrogensulfate. Its structure can be seen as a variant of the UCl₃ type structure with complex anions and contains the La³⁺ ions in ninefold coordination of oxygen atoms. Single crystals of Gd(HSeO₄)(SeO₄) crystallize from a solution of Gd₂O₃ in selenic acid (70% H₂SeO₄). In the orthorhombic crystal structure (Pbca, Z = 8, a = 920.4(1), b = 1351.6(2), c = 1004.0(1) pm, R_all = 0.0276) the Gd³⁺ ions are coordinated by eight oxygen atoms belonging to four SeO₄^2– and four HSeO₄^– ions. These are surrounded by four Gd³⁺ ions.     

Einfach und doppelt deprotonierte Maleinsäure in Praseodym‐hydrogenmaleat‐octahydrat,Pr(C4O4H3)3 · 8 H2O,und Praseodym‐maleatchlorid‐tetrahydrat,Pr(C4O4H2)Cl · 4 H2O

Single and Double Deprotonated Maleic Acid in Praseodymium Hydrogenmaleate Octahydrate, Pr(C₄O₄H₃)₃ · 8 H₂O, and Praseodymiummaleatechloride Tetrahydrate, Pr(C₄O₄H₂)Cl · 4 H₂O Single crystals of Pr(C₄O₄H₃)₃ · 8 H₂O grew by slow evaporation of a solution which had been obtained by dissolving Pr(OH)₃ in aqueous maleic acid. The triclinic compound (P1, Z = 2, a = 728.63(3), b = 1040.23(3), c = 1676.05(8) pm, α = 72.108(2)°, β = 87.774(2)°, γ = 70.851(2)°, R_all = 0.0261) contains Pr³⁺ ions in ninefold coordination of oxygen atoms which belong to two monodentate maleate ions and seven H₂O molecules. There is one further non‐coordinating maleate ion and one crystal water molecule in the unit cell. Thermal treatment of Pr(C₄O₄H₃)₃ · 8 H₂O leads first to the anhydrous compound which then decomposes to the respective oxide in two steps upon further heating. Evaporation of a solution of Pr(C₄O₄H₃)₃ · 8 H₂O which contained additional Cl^– ions yielded single crystals of Pr(C₄O₄H₂)Cl · 4 H₂O. In the crystal structure (monoclinic, P2₁/c, Z = 4, a = 866.0(1), b = 1344.3(1), c = 896.9(1) pm, β = 94.48(2)°, R_all = 0.0227), the Pr³⁺ ions are surrounded by nine oxygen atoms. The latter belong to four H₂O molecules and three maleate ions. Two of the latter act as bidentate ligands.     

Crystal Growth and Spectroscopic Characterisation of BiB3O6:RE3+ (RE3+ = Pr3+, Nd3+, Gd3+, Er3+, Tm3+)

Large single crystals of optical quality of BiB₃O₆:RE³⁺ (RE³⁺ = Pr³⁺, Nd³⁺, Gd³⁺, Er³⁺, Tm³⁺) were grown from nearly stoichiometric melts using the top‐seeding growth technique to dimensions up to 12 x 12 x 18 mm³. Absorption spectra were measured in the wavelength range from 10000 cm^‐1 to 30000 cm^‐1 with an absorption spectrometer to estimate the doping concentration of RE³⁺. For the determination of the phonon energies and the quenching behaviour of the host lattice IR and Raman spectra were recorded.     

AuSO4: A True Gold(II) Sulfate with an Au24+ Ion

Red single crystals of AuSO₄ have been obtained by evaporating a solution of Au(OH)₃ in concentrated sulfuric acid. The crystal structure (orthorhombic, Pbca, Z = 8, a = 854.9(2), b = 824.9(3), c = 1001.1(4) pm) exhibits the dumbbell shaped Au₂⁴⁺ cation (bond length Au–Au: 249 pm) which is coordinated by two chelating and two monodentate SO₄^2– groups. The monodentate sulfate anions act as chelating ligand to another Au₂⁴⁺ ion leading to infinite sheets according to [(Au₂)(SO₄)_4/2] which are stacked in [001] direction.