Ulrich Klement

β-PtO2: High pressure synthesis of single crystals and structure refinement

Abstract Single crystals of β-PtO2 have been grown from PtKC103-mixtures at 40 kbar, 1500 °C in a modified Belt-type apparatus using Pt-capsules. The crystals are orthorhombic, space group Pnnm, with a=4.4839(3) A, b=4.5385(6) A, c=3.1360(6) A and Z=2. Single crystal X-ray data confirmed the structure to be CaCl2-type, a distorted variant of the rutile structure. The PtO distances are 2 × 1.989(4) and 4 × 2.003(4) A, the shortest oxygenoxygen distance is 2.494(5) A. A discussion of some geometrical features is presented.

Spectroscopic studies of cyclo-metallated Pt(lI) complexes: optical absorption and emission and the structure of single crystal [Pt(bpm)(CN)2]·H2O (bpm = 2,2′-bipyrimidine)

Abstract The polarized optical absorption and emission spectra of single crystal [Pt(bpm)(CN) 2 ]·H 2 O (bpm =2,2′-bipyrimidine) have been measured as functions of temperature (1.9 K⩽ T ⩽295 K) and of homogeneous magnetic fields (0 ⩽ H ⩽6 T). Analysis of the spectra shows that the inter-complex coupling is weak and that the emission at low temperatures originates mainly from two types of traps located energetically by Δv ∼40 and ∼45 cm −1 , respectively, below the triplet exciton band. The spectroscopic properties are discussed on the basis of the crystallographic data for [Pt(bpm)(CN) 2 ]·H 2 O: monoclinic, space group P 2 1 / c , a = 7.076(1), b = 8.999(2), c = 18.127(2) )A, β = 99.84(1)°, V = 1137.29 A 3 , Z = 4, D x = 2.47 g cm −3 . Anisotropic refinement (2743 reflexes I >; 2σ( I ), 163 variables) resulted in R = 0.066, R w = 0.037, S = 0.78.

The crystal, molecular and electronic structures of copper(II)dipropylenetriamine thiocyanate nitrate

Abstract The crystal and molecular structure of Cu(dpta)(NCS)(NO3) where dpta= dipropylenetriamine is reported. The blue compound which crystallizes in space group P21/c with Z=4 and a=9.571(2), b=10.453(2), c=13.620(3) A, β=108.29(2)°, V=1294(1) A3 gave 4313 reflections with Rw=0.068. Cu(II) is four coordinate with three CuN contacts (2.017(6), 2.083(5) and 2.009(6) A) from the tri-dentate dpta and one contact (2.005(6) A) from the N-coordinated NCS group. The contact with an O atom from the NO3 group is at >;3.5 A. The CuN4group is almost planar, slightly rhombically distorted, and Cu is out of the 4N plane, the amine nitrogens being tilted towards the NCS group. The dpta ligand is in a symmetric conformation (k,k′) around the central CuN and the NCS group is linear but it is at 162° to the plane of the three dpta nitrogens. The observed molecular symmetry is explained by crowding of the CH2 groups on the one side of the CuN4 plane. This is consistent with electronic and ESR spectra and substantiated by MNDO and MM calculations. The red shift (ΔE∼400 cm−1) with the temperature observed in the electronic spectra and the polarizations can be explained in terms of dynamic Jahn-Teller coupling and displaced excited states.

Absorption and emission spectra and structure data of single crystal maleonitriledithiolate complexes of platinum(II)

Abstract [Bu 4 N] 2 [Pt(mnt) 2 ] crystallizes according to the space group P 1 with Z = 1. The anion [Pt(mnt) 2 ] 2− is closely planar and has a center of symmetry at the platinum atom. The absorption spectra of single crystal X 2 [Pt(mnt) 2 ] exhibit a strong structured band at ν ≈ 20 000 cm −1 (ϵ ≈ 3500 l mol −1 cm −1 ) and at its low-energy flank a system of weak bands with ϵ ≈ 80 l mol −1 cm −1 , which can be assigned to spin- allowed and spin-forbidden electronic transitions in the anion, respectively. The emission bands correspond to deactivations of the lowest excited triplet. The energies of the absorption and emission bands depend on the cation X.

Die Kristallstruktur von α-ΚΖnΡΟ4 / The Crystal Structure of α-KZnPO4

Single crystals of a-KZnPO4, the low-temperature modification of potassium zinc orthophosphate, were obtained from KZnPO4 powder by high pressure experiments in a modified Belt-type apparatus. The crystals are hexagonal, space group P 63, with a = 18.155(2), c = 8.504(1) Å, c/a = 0.4684 and Z = 24. The crystal structure, refined from diffractometer data to R = 0.077, Rw = 0.068, comprises an ordered network of ZnO4 and PO4 tetrahedra with rings of six tetrahedra vertical to the c-axis. The potassium ions are located in cavities formed by the rings.

Spectroscopic studies of cyclo-metallated pt(II) complexes: spectroscopic evidence of strong inter-complex coupling in single crystal [Pt(bpm)(CN)2]·DMF(bpm = 2, 2′-bipyrimidine)

Abstract The optical properties (polarized absorption and emission) of single crystal [Pt(bpm)(CN)2]·DMF under variation of temperature (1.9 K ⩽T⩽295 K) and homogeneous magnetic fields (0⩽H⩽ 6 T) are reported. When the magnetic field strength is raised from H=0 to 6 T, the low-temperature emission is blue shifted by 220 cm−1, the intensity increases by a factor of ∼27, and the lifetime is reduced from τ=1.8 ms to 15 μs. The spectroscopic results are explained on the basis of the crystal structure of [Pt(bpm)(CN)2]·DMF, which exhibits columns of [Pt(bpm)(CN)2] complexes with a nearly face-to-face arrangement and relatively short PtPt distances (∼3.28 A), yielding a distinct inter-complex coupling. Crystallographic data for [Pt(bpm)(CN)2]·DMF: monoclinic, space group P21/m, a=10.702(2), b =6.518(1), c=10.700(2) A,β=95.57(2)°, V=742.86 A3, Z=2, Dc=2.14g cm−3, μ(Mo Kα)=95.5 cm−1, R=0.069, Rw=0.056 for 113 variables and 3497 reflexes with I > 3σ(I).

Die Kristallstruktur von NaZnAsO4 / The Crystal Structure of NaZnAsO4

Single crystals of NaZnAsO4 were grown in a sodium molybdate flux. The compound crystallizes monoclinically, space group P21/n, with a = 8.951(1), b = 8.2085(9), c = 15.699(2) Å, β = 90.153(6)° and Ζ = 12. The structure was refined to R = 0.036, Rw = 0.035 for 3355 independent, absorption-corrected reflections. NaZnAsO4 belongs to the beryllonite (NaBePO4) structure type.

Gold-Alkalimetallsysteme, III. Hochdrucksynthese und Kristallstruktur von Rb3Au7 [1] / Gold-Alkali Metal-Systems, III. High Pressure Synthesis and Crystal Structure of Rb3Au7 [1]

Abstract The intermetallic compound Rb3Au7 could be synthesized from the elements at 4 kbar, 700 °C in a modified Belt-type apparatus. The structure (Cmmm; a = 5.579(1), b = 13.267(5), c = 7.265(2) Å; Z = 2; R = 0.035, Rw = 0,031) comprises three crystallographically independent Au atoms, arranged in layers along the c-axis. The shortest interatomic distances are Au -Au = 2.633Å, Au -Rb = 3.438Å and Rb -Rb = 3.622Å.

Hochdrucksynthese und Strukturverfeinerung von SrVO3, Sr2VO4 und Sr3V2O7 / High-Pressure Synthesis and Structure Refinement of SrVO3, Sr2VO4, and Sr3V2O7

Single crystals of SrVO3, Sr2VO4 and Sr3V2O7 have been obtained by high-pressure reactions in a modified belt-type apparatus. The crystal structures, refined from diffractometer data, are as follows: SrVO3, perovskite type, Pm3̄m, a = 3.8408(3) Å, R = 0.017, Rw = 0.018, composition from occupancy refinement of oxygen positions SrVO2.93(2); Sr2VO4, K2NiF4 type, I 4/mmm, a = 3.837(1), c = 12.569(1) Å, R = 0.014, Rw = 0.017; Sr3V2O7, Sr3Ti2O7 type, I 4/mmm, a = 3.839(1), c = 20.262(2) Å, R = 0.020, Rw = 0.029.

Hochdrucksynthese und Kristallstruktur von Kalium- und Rubidiumdiwolframat(VI), K2W2O7 und Rb2W2O7 / High-Pressure Synthesis and Crystal Structure of Potassium and Rubidium Ditungstate(VI), K2W2O7 und Rb2W2O7

Potassium tungstate, K2WO4, decomposes at high pressures to give K2W2O7 and other products. Single crystals of K2W2O7 could be synthesized from a mixture of K2WO4 + WO3 at 40kbar, 1000 °C. The crystals are monoclinic, space group P21/c, with a = 3.883(1) A, b = 13.653(4) Å, c = 5.960(1) Å, β = 90.40(3)°, and Ζ = 2. The structure is comprise of distorted WO6-octahedra (W–O = 1.75-2.13 A) which are connected by corner- and edgesharing, thus forming layers with a sequence ABAB ... along [010]. The potassium ions are situated between the layers with K–O distances of 2.66-3.04 A. Rb2W2O7, synthesized from a Rb2WO4/WO3-mixture at 40 kbar, 1000 °C, is isostructural with K2W2O7 (a = 3.9645(4) Å, b = 14.119(1) Å, c = 6.0415(5) Å,β = 90.446(9)°.