Thomas Schleid

Carboxyl-Functionalized Task-Specific Ionic Liquids for Solubilizing Metal Oxides

Imidazolium, pyridinium, pyrrolidinium, piperidinium, morpholinium, and quaternary ammonium bis(trifluoromethylsulfonyl)imide salts were functionalized with a carboxyl group. These ionic liquids are useful for the selective dissolution of metal oxides and hydroxides. Although these hydrophobic ionic liquids are immiscible with water at room temperature, several of them form a single phase with water at elevated temperatures. Phase separation occurs upon cooling. This thermomorphic behavior has been investigated by (1)H NMR, and it was found that it can be attributed to the temperature-dependent hydration and hydrogen-bond formation of the ionic liquid components. The crystal structures of four ionic liquids and five metal complexes have been determined.

Versatility and low-temperature synthetic potential of ammonium halides

Etude des reactions des halogenures de NH 4 avec: les sesquioxydes de terres rares, les metaux, les sulfures, seleniures, phosphures, carbures. Elles peuvent etre divisees en 2 groupes: les reactions redox et les reactions acide-base

Single crystals of rare earth oxides from reducing halide melts

Abstract The action of alkali metals ( A  Li - Cs ) on rare earth trihalides MX 3 results in the formation of binary and ternary reduced halides and, additionally and frequently, alkali halides AX. When oxygen is present, as a contamination of the reaction container, as oxyhalide MOX or as sesquioxide M 2 O 3 , crystallization of oxyhalides ( e.g . Sm 4 OCl 6 , NdOCl) or even of the sesquioxides themselves is observed upon cooling of these strongly reducing melts. The crystal structures of Sm 2 O 3 (B type, C 2/ m , a = 1419.75(9), b = 362.73(3), c = 885.61(5) pm, β = 99.986(5) °, R = 0.037, R w = 0.028), Yb 2 O 3 and Sc 2 O 3 (both C type, Ia 3, a = 1043.42(4) and 984.46(4) pm, R = 0.065, R w = 0.058 and R = 0.055, R w = 0.045 respectively) have been refined from single-crystal diffractometer data.

The Laccase-Catalyzed Domino Reaction between Catechols and Heterocyclic 1,3-Dicarbonyls and the Unambiguous Structure Elucidation of the Products by NMR Spectroscopy and X-ray Crystal Structure Analysis

The laccase-catalyzed reaction between catechols and heterocyclic 1,3-dicarbonyls (pyridinones, quinolinones, thiocoumarins) using aerial oxygen as the oxidant delivers benzofuropyridinones, benzofuroquinolinones, and thiocoumestans in a simple fashion, highly regioselectively with yields ranging from 55 to 98%. With barbituric acid derivatives the exclusive formation of dispiropyrimidinone derivatives takes place. The unambiguous and complete structure elucidation of all reaction products has been achieved by means of NMR spectroscopic methods (HSQMBC and band-selective HMBC) as well as by X-ray crystal structure analysis.

M10S14O-type oxysulphides (M≡La, Ce, Pr, Nd, Sm) as an oxygen trap in oxidation reactions of reduced lanthanide chlorides with sulphur

Abstract Oxidation of reduced chlorides (KM2Cl5; M  Nd, Sm) or chloride-hydrides (MClH0.67; M  La, Ce, Pr) of the lanthanides with sulphur in the presence of NaCl in the latter case (tantalum capsule, 850 °C, 7 days) results in the formation of binary sulphides and ternary chlorides with potassium and sodium respectively, both with trivalent cations (M3+), as the main products. Oxidic impurities (e.g. MOCl) react to yield M10S14O-type oxysulphides (M  La, Ce, Pr, Nd, Sm) in small amounts as bead-shaped single crystals of high quality (M10S14O, tetragonal, I4 1 acd (no. 142), Z = 8; M  La: a = 1536.51(4) pm, c = 2037.85(9) pm, R = Rw = 0.028; M  Ce: a = 1521.24(4) pm, c = 2018.43(9) pm, R = 0.014, Rw = 0.013; M  Pr: a = 1511.63(4) pm, c = 2006.27(9) pm, R = 0.028, Rw = 0.029; M  Nd: a = 1503.80(4) pm, c = 1996.46(8) pm, R = 0.015, Rw = 0.014; M  Sm: a = 1485.96(4) pm, c = 1974.04(8) pm, R = 0.016, Rw = 0.014). Their crystal structure is built up from isolated O2−-centred tetrahedra [OM4]10+ which are surrounded by a “sea” of lanthanide sulphide according to the formulation [OM4]S7M6S7. Three crystallographically independent M3+ cations occur with coordination numbers of eight (M1: seven plus one S2−; M2: six plus one S2− and one O2−, both bicapped trigonal prisms; M3: eight S2−, trigonal dodecahedron). Four different S2− (coordination numbers from four plus one to six) provide for the necessary coupling of the isolated [O(M2)4] tetrahedra to their metal sulphide vicinity.

Facile synthesis of UCl4 and ThCl4, metallothermic reductions of UCl4 with alkali metals and crystal structure refinements of UCl3, UCl4 and Cs2UCl6

Abstract Uranium and thorium tetrachloride (UCl 4 and ThCl 4 ) were obtained via the ammonium chloride route from UH 3 and thorium metal respectively, with the ternary chlorides (NH 4 ) 2 UCl 6 and (NH 4 ) 2 ThCl 6 acting as intermediates. The crystal structure of UCl 4 was refined ( R = 0.031, R w = 0.026). Cs 2 UCl 6 and Cs 2 ThCl 6 were synthesized, their lattice constants refined from powder data, and the crystal structure of Cs 2 UCl 6 refined from single-crystal data ( R = 0.066, R w = 0.052). Some indication for stacking disorder in the [00.1] direction was found. Metallothermic reductions of UCl 4 with lithium and sodium led to UCl 3 whose crystal structure was also refined ( R = 0.029, R w = 0.023). Potassium reduced UCl 4 to K 2 UCl 5 . No further reduction could be detected.

An oxychloride of divalent ytterbium: Yb4OCl6☆

Abstract Lemon-coloured single crystals of the first oxychloride of divalent ytterbium Yb 4 OCl 6 are obtained by metallothermic reduction of YbCl 3 (contaminated with YbOCl) with metallic lithium in a sealed tantalum container at 900 and 750 °C. Yb 4 OCl 6 crystallizes with the hexagonal system, space group P6 3 mc , Z = 2 with a = 913.78(4) pm, c = 688.70(5) pm, c / a = 0.754 and V m = 149.97(2)cm 3 mol −1 . An important feature of the crystal structure of Yb 4 OCl 6 is the O 2− centred (Yb 2+ ) 4 tetrahedron that is surrounded by 18 Cl − ions. These provide the necessary connections to other [OYb 4 ] units. The [OYb 4 ] tetrahedra are, viewed by themselves, arranged in the fashion of the hexagonal close packed structures.

The metallothermic reduction of several rare-earth trichlorides with lithium and sodium

Abstract The metallothermic reduction of the trichlorides of europium, ytterbium, samarium, thulium, dysprosium and neodymium with lithium and sodium produces chlorides of the divalent lanthanides when stoichiometric quantities are used. The systems LiCl-MCl 2 (M ≡ Nd, Sm, Eu) and NaCl-MCl 2 (M ≡ Sm, Eu, Dy, Tm, Yb) are simply eutectic. Lattice constants were determined from X-ray powder patterns and the crystal structure of SmCl 2 was refined. NdCl 2 , SmCl 2 and EuCl 2 crystallize with the PbCl 2 -type structure (CN 9), DyCl 2 with the SrBr 2 -type structure (CN 8) and TmCl 2 and YbCl 2 with the SrI 2 -type structure (CN 7). The systems LiCl-MCl 2 (M ≡ Dy, Tm, Yb) contain the ternary chlorides LiM 2 Cl 5 . The crystal structure of LiTm 2 Cl 5 (CN 8) was refined and is compared with that of LiDy 2 Cl 5 which has been determined previously.

First crystal structure determination and high-frequency EPR study of an organoarsanecopper radical complex

Abstract The red radical complex {(μ-bptz)[Cu(AsPh3)2]2}(BF4) 1, bptz=3,6-bis(2-pyridyl)-1,2,4,5-tetrazine, was obtained as a stable species and characterized by X-ray crystallography, spectroelectrochemistry and EPR at 9.5 and 285 GHz. Comparison with the previously reported {(μ-bptz)[Cu(PPh3)2]2}(BF4) 2 reveals longer Cu-element bonds by about 0.1 A but otherwise a similar “organic sandwich” structure involving intramolecular π(phenyl)–π(tetrazine)–π(phenyl) interactions, a 3+1 coordination at the copper(I) centers, and averaged tetrazine intraring bond distances. Reversible oxidation to a blue dication with an intense MLCT band at 650 nm occurs at −0.24 V vs. Fc+/o. EPR studies show the effect of the higher spin–orbit coupling constant of the As vs. P atoms through slightly larger g anisotropy as determined through high frequency measurements.

Tb2Se2O7: Terbium(III) Oxide Oxoselenate(IV) according to Tb2O[SeO3]2 with a “Lone—Pair” Channel Structure

The colourless title compound Tb2Se2O7 (≡ Tb2O [SeO3]2, terbium(III) oxide oxoselenate(IV)) was obtained by reacting a mixture of Tb4O7, Tb and SeO2 in a 3:2:14-molar ratio at 850 °C for seven days in an evacuated silica vessel as needle-shaped single crystals. It crystallizes tetragonally (space group: P42/ncm, a = 1064.57(8), c = 521.56(4) pm, c/a = 0.490, Z = 4) and exhibits Tb3+ cations in square-antiprismatic coordination of eight oxygen atoms each. Six of the latter belong to six different isolated ψ1-tetrahedral [SeO3]2— anions whereas the remaining two are not bonded to selenium at all. Their coordination sphere actually consists of four Tb3+ cations arranged as tetrahedron. These [OTb4]10+ tetrahedra form infinite one-dimensional {[OTb4/2]4+} chains along [001] by sharing trans-oriented edges which are packed such that a central strand is quadratically surrounded in (001) projection by four chains at a distance of √2 and another square of four more of them a factor of √2 (≡ the value of a) further apart and rotated by 45°. Charge balance and three-dimensional interconnection of this particular rod-packing occurs via discrete trigonal [SeO3]2— pyramids so that the whole structure gets strongly influenced by the stereochemical lone-pair activity of these groups. Remarkably enough, the 4¯ symmetry of the {[OTb4/2]4+} chains is perfectly repeated by the “lone-pair” channels of the non-binding electrons at the Se4+ cations. Tb2Se2O7: Terbium(III)-Oxid-Oxoselenat(IV) gemas Tb2O[SeO3]2 mit einer Kanalstruktur aus nicht-bindenden Elektronenpaaren Die farblose Titelverbindung Tb2Se2O7 (≡ Tb2O-[SeO3]2, Terbium(III)-Oxid-Oxoselenat(IV)) wurde durch die Umsetzung eines Gemenges Tb4O7, Tb und SeO2 im molaren Verhaltnis 3:2:14 in evakuierten Quarzglasampullen innerhalb von sieben Tagen bei 850 °C in Form von nadelformigen Einkristallen erhalten. Sie kristallisiert tetragonal (Raumgruppe: P42/ncm; a = 1064, 57(8), c = 521, 56(4) pm, c/a = 0, 490; Z = 4) und enthalt Tb3+-Kationen in quadratisch-antiprismatischer Koordination von acht Sauerstoffatomen. Sechs davon gehoren zu sechs unterschiedlichen, isolierten, ψ1-tetraedrischen [SeO3]2—-Anionen, wahrend die restlichen beiden nicht an Selen gebunden sind. Deren Koordinationssphare besteht vielmehr aus vier Tb3+-Kationen in tetraedrischer Anordnung. Diese [OTb4]10+-Tetraeder bilden durch Verknupfung uber trans-standige Kanten eindimensional unendliche Ketten {[OTb4/2]4+} parallel [001], die so gepackt sind, das ein Zentralstrang in (001)-Projektion im Abstand √2 quadratisch von vier nahen und von noch vier um den Faktor √2 (≡ a) weiter entfernten Ketten, deren projiziertes Quadrat um 45° gedreht ist, umgeben wird. Der Ladungsausgleich und die dreidimensionale Vernetzung dieser speziellen Stabpackung erfolgt durch diskrete, trigonale [SeO3]2—-Pyramiden, so das die Gesamtstruktur stark von der stereochemischen Aktivitat der nicht-bindenden Elektronenpaare dieser Baugruppen beeinflust ist. Bemerkenswerterweise wiederholt sich die 4¯-Symmetrie der {[OTb4/2]4+}-Ketten auch in den Kanalen, die durch die nicht-bindenden Elektronenpaare („lone pairs”) der Se4+-Kationen gebildet werden.