Ingo Hartenbach

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.

A Five-Center Redox System: Molecular Coupling of Two Noninnocent Imino-o-benzoquinonato-Ruthenium Functions through a π Acceptor Bridge

Combining the concepts of noninnocent behavior of metal/ligand entities and the coupling of redox-active moieties via an electronically mediating bridge led to the synthesis and the structural, electrochemical, and spectroscopic characterization of [Cl(Q)Ru(mu-tppz)Ru(Q)Cl](n) where Q(o) is 4,6-di-tert-butyl-N-phenyl-o-iminobenzoquinone and tppz(o) is 2,3,5,6-tetrakis(2-pyridyl)pyrazine, the available oxidation states being Ru(II,III,IV), Q(o,*-,2-), and tppz(o,*-,2-). One-electron transfer steps between the n = (2-) and (4+) states were studied by cyclic voltammetry and by EPR, UV-vis-NIR spectroelectrochemistry for the structurally characterized anti isomer of [Cl(Q)Ru(mu-tppz)Ru(Q)Cl](PF(6))(2), 2(PF(6))(2), the only configuration obtained. The combined investigations reveal that 2(2+) is best described as [Cl(Q(*-))Ru(III)(mu-tppz(o))Ru(III)(Q(*-))Cl](2+) with antiferromagnetic coupling between the ruthenium(III) and the iminosemiquinone components at each end. A metal-based spin as evident from large g factor anisotropy (EPR) and an intense intervalence absorption band at 1850 nm in the near-infrared (NIR) suggest that oxidation occurs at both iminosemiquinones to yield two Ru(II,III)-bonded quinones, implying redox-induced electron transfer. Reduction takes place stepwise at the metal centers yielding iminosemiquinone complexes of Ru(III,II) as evident from radical complex EPR spectra with small (99,101)Ru hyperfine contributions. After complete metal reduction to ruthenium(II) the bridging ligand tppz is being reduced stepwise as apparent from typical NIR absorption bands around 1000 nm and from small g anisotropy of the monoanion [Cl(Q(*-))Ru(II)(mu-tppz(*-))Ru(II)(Q(*-))Cl](-). A structure-based DFT calculation confirms the Ru-Cl character of the HOMO and the iminoquinone-dominated LUMO and illustrates the orbital interaction pattern of the five electron transfer active components in this new system.

YF[MoO4] and YCl[MoO4]: Two halide derivatives of yttrium ortho-oxomolybdate: Syntheses, structures, and luminescence properties

The halide derivatives of yttrium ortho-oxomolybdate YX[MoO 4] (X = F, Cl) both crystallize in the monoclinic system with four formula units per unit cell. YF[MoO 4] exhibits a primitive cell setting (space group P21/ c; a = 519.62(2) pm, b = 1225.14(7) pm, c = 663.30(3) pm, beta = 112.851(4) degrees ), whereas the lattice of YCl[MoO 4] shows face-centering (space group C2/m; a = 1019.02(5) pm, b = 720.67(4) pm, c = 681.50(3) pm, beta = 107.130(4) degrees ). The two compounds each contain crystallographically unique Y (3+) cations, which are found to have a coordination environment of six oxide and two halide anions. In the case of YF[MoO 4], the coordination environment is seen as square antiprisms, and for YCl[MoO 4], trigon-dodecahedra are found. The discrete tetrahedral [MoO 4] (2-) units of the fluoride derivative are exclusively bound by six terminal Y (3+) cations, while those of the chloride compound show a 5-fold coordination around the tetrahedra with one edge-bridging and four terminal Y (3+) cations. The halide anions in each compound exhibit a coordination number of two, building up isolated planar rhombus-shaped units according to [Y 2F 2] (4+) in YF[MoO 4] and [Y 2Cl 2] (4+) in YCl[MoO 4], respectively. Both compounds were synthesized at high temperatures using Y2O3, MoO3, and the corresponding yttrium trihalide in a molar ratio of 1:3:1. Single crystals of both are insensitive to moist air and are found to be coarse shaped and colorless with optical band gaps situated in the near UV around 3.78 eV for the fluoride and 3.82 eV for the chloride derivative. Furthermore, YF[MoO 4] seems to be a suitable material for doping to obtain luminescent materials because the Eu (3+)-doped compound shows an intense red luminescence, which has been spectroscopically investigated.

NaY3S3[SiS4]: a sodium-containing yttrium sulfide thiosilicate with channel structure

Abstract The reaction of sodium bromide (NaBr), yttrium (Y), sulfur (S) and silicon disulfide (SiS 2 ) in the molar ratio 1:4:6:2 with an excess of NaBr as flux in evacuated silica ampoules at 850°C for 7 days leads to the formation of deep red, hexagonal pillar-shaped single crystals of the title compound. NaY 3 S 3 [SiS 4 ] crystallizes hexagonally in the space group P 6 3 ( a =976.57(7), c =570.61(5) pm; Z =2). The sodium cations are situated in the trigonal antiprismatic holes (CN=6) of a channel along [001] that is built by non -silicon bonded sulfide anions, which on their part are surrounded by four Y 3+ and two Na + cations. The yttrium cations are surrounded by eight sulfur atoms in the shape of a square antiprism divided into four silicon- and four non-silicon-bonded sulfide anions. Finally, all discrete [SiS 4 ] 4− tetrahedra point in the same direction along the polar c -axis. Therefore, the whole structure of NaY 3 S 3 [SiS 4 ] remains non-centrosymmetric.

Yttrium(III) oxomolybdates(VI) as potential host materials for luminescence applications: an investigation of Eu3+-doped Y2[MoO4]3 and Y2[MoO4]2[Mo2O7]

Two ternary yttrium(III) oxomolybdates(VI) are investigated, both structurally and spectroscopically. The crystal structure of Y2[MoO4]3 was solved at room temperature in the orthorhombic space group Pba2 (a = 1030.21(3), b = 1032.41(3), c = 1057.25(3) pm, Z = 4). In the unit cell, three discrete ortho-oxomolybdate(VI) units [MoO4]2− and two Y3+ cations, both with CN = 7 featuring a monocapped trigonal-prismatic oxygen environment, can be distinguished. Y2[MoO4]2[Mo2O7] crystallizes monoclinically in the space group P21/c (a = 681.85(2), b = 959.13(3), c = 1052.99(3) pm, β = 105.586(2)°) with two formula units per unit cell. In this compound the anionic environment of the crystallographically unique Y3+ cations also comprises seven oxygen atoms forming a monocapped trigonal prism. Furthermore, the crystal structure features both tetrahedral [MoO4]2− and pyroanionic [Mo2O7]4− entities, the latter in staggered conformation, with the bridging oxygen atom between the two vertex-shared [MoO4]2− tetrahedra residing on an inversion centre. Besides self-activated emission, resulting from the oxomolybdate(VI) units (maximum at around 600 nm), both compounds have the potential to be used as luminescence host materials, shown by spectroscopic studies involving Eu3+ as a sensitive probe. The emission spectra of Y2[MoO4]3:Eu3+ and Y2[MoO4]2[Mo2O7]:Eu3+ are dominated by the Eu3+-typical 5D0 → 7F2 transition at 614 nm. In the excitation spectra, aside from 4f-interconfigurational Eu3+ transitions at lower energies, broad charge-transfer (CT) bands due to O2− → Eu3+ or O2− → Mo6+ transitions dominate at higher energies. Comparing the diffuse reflectance spectra (DRS) of the undoped with the Eu3+-doped materials, the O2− → Mo6+ LMCT process proves to be crucial for the position of the broad CT band in the excitation spectra of both yttrium oxomolybdates(VI).

Thiosilicate der Selten‐Erd‐Elemente: I. Die isotypen Verbindungen KCe[SiS4] und Eu2[SiS4]

Die beiden isotypen Thiosilicate KCe[SiS4] (a = 649, 15(6), b = 656, 18(6), c = 863, 96(8) pm, β = 107, 531(9)°) und Eu2[SiS4] (a = 651, 71(6), b = 659, 54(6), c = 821, 93(8) pm, β = 108, 437(9)°) kristallisieren monoklin in der Raumgruppe P21/m mit Z = 2. Bei der Umsetzung von KCl, Ce2S3 und SiS2 im Verhaltnis 1 : 1 : 1 mit der 6-fachen molaren Menge an KCl als Flusmittel in evakuierten Kieselglasampullen (7 d, 820°C) werden braunlich gelbe, plattchenformige, luft- und wasserstabile Einkristalle von KCe[SiS4] erhalten. Die Reaktion von Eu, S und SiS2 im Verhaltnis 2 : 2 : 1 in einem Uberschus an CsCl als Flusmittel liefert, ebenfalls in evakuierten Kieselglasampullen (7 d, 850°C), tiefrote plattchenformige Einkristalle von Eu2[SiS4], die einige Tage an Luft unzersetzt bleiben. Die Kristallstruktur enthalt isolierte ortho-Thiosilicat-Einheiten, die zusammen mit den Ce3+ bzw. (Eu2)2+-Kationen gewellte anionische Schichten gemas {(Ce[SiS4])—} bzw. {(Eu2[SiS4])2—} parallel (001) ausbilden. Diese sind alternierend mit kationischen Schichten aus K+- bzw. (Eu1)2+-Kationen gestapelt. Die Kationen der Punktlagen fur K+ und (Eu1)2+ betatigen eine Koordinationszahl von acht und weisen ein doppelt uberkapptes trigonales Prisma als Koordinationsfigur auf. Fur die Kationen Ce3+ und (Eu2)2+ kann das Koordinationspolyeder als (2+1)-fach uberkapptes trigonales Prisma (CN = 8 + 1) beschrieben werden. Beim formalen Ubergang von KCe[SiS4] nach Eu2[SiS4] (≡ EuEu[SiS4]) ist Eu2+ also in der Lage, sowohl K+ als auch Ce3+ isomorph zu ersetzen. Thiosili-Thiosilicates of the Rare-Earth Elements: I. The Isotypic Compounds KCe[SiS4] and Eu2[SiS4] Both isotypic thiosilicates KCe[SiS4] (a = 649.15(6), b = 656.18(6), c = 863.96(8) pm, β = 107.531(9)°) and Eu2[SiS4] (a = 651.71(6), b = 659.54(6), c = 821.93(8) pm, β = 108.437(9)°) crystallize monoclinically in the space group P21/m and Z = 2. By the reaction of KCl, Ce2S3 and SiS2 in the ratio 1 : 1 : 1 using a sixfold molar amount of KCl as flux in evacuated silica tubes (7 d, 850°C) brownish yellow, plate-shaped single crystals, resistant both to air and water are obtained. The conversion of Eu, S and SiS2 in molar ratios of 2 : 2 : 1 with an excess of CsCl as flux in evacuated silica tubes (7 d, 850°C) leads to deep red, plate-shaped single crystals, which remain air- and water-stable for a few days. The crystal structure contains isolated ortho-thiosilicate units, that together with the Ce3+ or (Eu2)2+ cations build corrugated anionic layers parallel (001) according to {(Ce[SiS4])—} and {(Eu2[SiS4])2—}, respectively. These layers are alternatingly piled with cationic layers consisting solely of K+ or (Eu1)2+ cations. The latter show coordination numbers of eight in the shape of a bicapped trigonal prism, whereas the cations of the position Ce3+ and (Eu2)2+ have a (2+1)-fold capped trigonal prismatic environment with a coordination number of 8+1. The comparison of both compounds KCe[SiS4] and Eu2[SiS4] (≡ EuEu[SiS4]) demonstrates, that Eu2+ is able to substitute both K+ and Ce3+ isomorphically.

Eu5F[SiO4]3 und Yb5S[SiO4]3: Gemischtvalente Lanthanoid-Silicate mit Apatit-Struktur†

Die Umsetzung von Eu, EuF3, Eu2O3 mit SiO2 in Gegenwart von NaF als Flusmittel in evakuierten Goldampullen ergibt bei einer Temperatur von 1000 °C und einer Temperzeit von 10h dunkelrote, plattchenformige Einkristalle von Eu5F[SiO4]3. Ebenfalls dunkelrote, jedoch saulenformige Einkristalle von Yb5S[SiO4]3 werden bei der Umsetzung von Yb, Yb2O3 und S mit SiO2 in Anwesenheit von CsBr als Flusmittel in evakuierten Kieselglasampullen bei 850 °C und 7d Temperzeit erhalten. Beide Verbindungen kristallisieren hexagonal (P63/m, Z = 2; Eu5F[SiO4]3: a = 954, 79(9), c = 704, 16(6) pm; Yb5S[SiO4]3: a = 972, 36(9), c = 648, 49(6) pm), im Falle von Eu5F[SiO4]3 analog zum Mineral Fluorapatit und Yb5S[SiO4]3 im Bromapatit-Typ. Die isolierte [SiO4]4—-Tetraeder enthaltende Kristallstruktur unterscheidet zwei Selten-Erd-Kationenlagen mit Koordinationszahlen von neun (M1) und sieben (M2), wobei die Lage M1 des Europium-Fluoridsilicats fast ausschlieslich mit Eu2+-Kationen besetzt ist, wahrend sie beim Ytterbium-Sulfidsilicat im Verhaltnis 1 : 1 zwei- und dreiwertige Yb-Kationen enthalt. Dagegen befinden sich in beiden Fallen nur M3+-Ionen auf der M2-Lage. Eu5F[SiO4]3 and Yb5S[SiO4]3: Mixed-Valent Lanthanoid Silicates with Apatite-Type of Structure By the reaction of Eu, EuF3, Eu2O3 with SiO2 in evacuated gold ampoules, using NaF as flux, at a temperature of 1000 °C for ten hours, dark-red, platelet-shaped single crystals of Eu5F[SiO4]3 are obtained. Similarly dark-red, but pillar-shaped single crystals of Yb5S[SiO4]3 are obtained by the reaction of Yb, Yb2O3 and S with SiO2 in the presence CsBr as flux in evacuated silica ampoules at 850 °C and an annealing time of seven days. Both compounds crystallize hexagonally (P63/m, Z = 2; Eu5F[SiO4]3: a = 954.79(9), c = 704.16(6) pm; Yb5S[SiO4]3: a = 972.36(9), c = 648.49(6) pm) in the case of Eu5F[SiO4]3 analogous to the mineral fluorapatite and for Yb5S[SiO4]3 as a bromapatite—type variety. The crystal structure containing isolated [SiO4]4— tetrahedra distinguishes two rare-earth cation positions with coordination numbers of nine (M1) and seven (M2), in which the position M1 of the europium fluoride silicate is almost exclusively occupied by Eu2+ cations, whereas in ytterbium sulfide silicate it contains di- and trivalent Yb cations in the ratio 1 : 1. In both cases, however, the M2 position is only populated with M3+.

Zwei Chloridsilicate des Yttriums: Y3Cl[SiO4]2 und Y6Cl10[Si4O12]

Das chloridarme Yttrium(III)–Chloridsilicat Y3Cl[SiO4]2 kristallisiert orthorhombisch (a = 685,84(4), b = 1775,23(14), c = 618,65(4) pm; Z = 4) in der Raumgruppe Pnma. Farblose, plattchenformige, stark lichtreflektierende, luft- und wasserunempfindliche Einkristalle werden bei der Umsetzung von Y2O3, YCl3 und SiO2 im stochiometrischen Verhaltnis 4 : 1 : 6 mit der zehnfachen molaren Menge an YCl3 als Flusmittel in evakuierten Quarzglasampullen (7 d, 1000 °C) erhalten. Die isolierte Orthosilicat-Einheiten [SiO4]4– enthaltende Kristallstruktur besteht aus kationischen {(Y2)Cl}2+-Schichten, die alternierend mit anionischen {(Y1)2[SiO4]2}2–-Doppelschichten parallel (010) gestapelt sind. Die beiden kristallographisch unterschiedlichen Y3+-Kationen betatigen jeweils Koordinationszahlen von acht. Dabei ist Y1 verzerrt trigonal-dodekaedrisch von einem Cl–- und 7 O2–-Anionen umgeben, wahrend das Koordinationspolyeder um Y2 die Form eines doppelt uberkappten trigonalen Prismas aus 2 Cl–- und 6 O2–-Anionen aufweist. Das chloridreiche Chloridsilicat Y6Cl10[Si4O12] kristallisiert monoklin (a = 1061,46(8), b = 1030,91(6), c = 1156,15(9) pm, β = 103,279(8)°; Z = 2) in der Raumgruppe C2/m. Bei der Umsetzung von Y2O3, YCl3 und SiO2 im molaren Verhaltnis 2 : 5 : 6 mit der doppelten Menge an YCl3 als Flusmittel in evakuierten Quarzglasampullen (7 d, 850 °C) fallen farblose, luft- und wasserresistente, sprode Einkristalle in Form von pseudo-oktagonalen Saulen an. Auch hier liegt eine Schichtstruktur parallel (001) vor, die sich durch kationische {(Y2)5Cl9}6+-Doppelschichten und anionische {(Y1)Cl[Si4O12]}6–-Schichten auszeichnet, wobei letztere diskrete cyclo-Tetrasilicat-Einheiten [Si4O12]8– aus vier ringformig eckenverknupften [SiO4]-Tetraedern in allseits ekliptischer Anordnung beinhalten. Die Koordinationssphare um (Y1)3+ (CN = 8) hat die Form einer leicht verzerrten hexagonalen Bipyramide aus 2 Cl–- und 6 O2–-Anionen. Die 5 Cl–- und 2 O2–-Anionen des Koordinationspolyeders um (Y2)3+ (CN = 7) bilden eine stark verzerrte pentagonale Bipyramide. Two Chloride Silicates of Yttrium: Y3Cl[SiO4]2 and Y6Cl10[Si4O12] The chloride-poor yttrium(III) chloride silicate Y3Cl[SiO4]2 crystallizes orthorhombically (a = 685.84(4), b = 1775.23(14), c = 618.65(4) pm; Z = 4) in space group Pnma. Single crystals are obtained by the reaction of Y2O3, YCl3 and SiO2 in the stoichiometric ratio 4 : 1 : 6 with ten times the molar amount of YCl3 as flux in evacuated silica tubes (7 d, 1000 °C) as colorless, strongly light-reflecting platelets, insensitive to air and water. The crystal structure contains isolated orthosilicate units [SiO4]4– and comprises cationic layers {(Y2)Cl}2+ which are alternatingly piled parallel (010) with anionic double layers {(Y1)2[SiO4]2}2–. Both crystallographic different Y3+ cations exhibit coordination numbers of eight. Y1 is surrounded by one Cl– and 7 O2– anions as a distorted trigonal dodecahedron, whereas the coordination polyhedra around Y2 show the shape of bicapped trigonal prisms consisting of 2 Cl– and 6 O2– anions. The chloride-rich chloride silicate Y6Cl10[Si4O12] crystallizes monoclinically (a = 1061,46(8), b = 1030,91(6), c = 1156,15(9) pm, β = 103,279(8)°; Z = 2) in space group C2/m. By the reaction of Y2O3, YCl3 and SiO2 in 2 : 5 : 6-molar ratio with the double amount of YCl3 as flux in evacuated silica tubes (7 d, 850 °C), colorless, air- and water-resistant, brittle single crystals emerge as pseudo-octagonal columns. Here also a layered structure parallel (001) with distinguished cationic double-layers {(Y2)5Cl9}6+ and anionic layers {(Y1)Cl[Si4O12]}6– is present. The latter ones contain discrete cyclo-tetrasilicate units [Si4O12]8– of four cyclically corner-linked [SiO4] tetrahedra in all-ecliptical arrangement. The coordination sphere around (Y1)3+ (CN = 8) has the shape of a slightly distorted hexagonal bipyramid comprising 2 Cl– and 6 O2– anions. The 5 Cl– and 2 O2– anions building the coordination polyhedra around (Y2)3+ (CN = 7) form a strongly distorted pentagonal bipyramid.

Ho2O[SiO4] und Ho2S[SiO4]: Zwei Chalkogenid-Derivate von Holmium(III)-ortho- Oxosilicat

Ho2O[SiO4] kristallisiert monoklin mit der Raumgruppe P21/c (a = 904, 15(9), b = 688, 93(7), c = 667, 62(7) pm, β = 106, 384(8)°, Z = 4) im A-Typ der Selten-Erd(III)-Oxid-Oxosilicate. Es entsteht in Form gelber, plattchenformiger Einkristalle als Nebenprodukt eines Versuchs zur Darstellung von Ho3Cl[SiO4]2 nach Umsetzung von Ho2O3 und SiO2 im Verhaltnis 4 : 6 mit einem Uberschus an HoCl3 als Flusmittel durch siebentagiges Tempern bei 1000 °C in evakuierten Kieselglasampullen. Die beiden kristallographisch unterschiedlichen Ho3+-Kationen weisen Koordinationszahlen von 8+1 und 7 auf, mit 2+1-fach uberkappten trigonalen Prismen bzw. Oktaedern, deren eine Ecke sich durch zwei statt einem koordinierenden Teilchen zur Kante umformt, als Koordinationsfiguren. Das nicht an Silicium gebundene O2—-Anion ist tetraedrisch von vier Ho3+-Kationen umgeben und bildet mit diesen durch Kanten- und Eckenverknupfung eine Schicht gemas {[(O5)(Ho1)1/1(Ho2)3/3]4+} parallel (100) aus, in deren rautenformigen Maschen die isolierten Oxosilicat-Tetraeder [SiO4]4— zu liegen kommen. Ho2S[SiO4] kristallisiert orthorhombisch mit der Raumgruppe Pbcm (a = 605, 87(5), b = 690, 41(6), c = 1064, 95(9) pm, Z = 4). Auch dieses stellt ein Nebenprodukt dar, das bei der Synthese von Ho2OS2 durch Reaktion eines Gemenges von Ho2O3, Ho und S mit der Wand der als Behalter verwendeten evakuierten Kieselglasampulle in einem Uberschus an CsCl als Flusmittel bei 800 °C einkristallin entsteht. Die Struktur der gelben, plattchenformigen, luft- und wasserbestandigen Einkristalle unterscheidet ebenfalls zwei Ho3+-Kationen mit doppelt uberkappten trigonalen Prismen bzw. Trigondodekaedern als Koordinationspolyedern fur CN = 8. Die S2—-Anionen sind annahernd quadratisch planar von vier Ho3+-Kationen umgeben, befinden sich jedoch vollstandig auserhalb dieser Ebene. Die [SHo4]10+-Quadrate bilden durch Eckenverknupfung eine stark gewellte Schicht gemas {[(S)(Ho1)2/2(Ho2)2/2]4+} senkrecht zu [100]. Die isolierten Oxosilicat-Tetraeder [SiO4]4— kommen hier im Gegensatz zum Oxid-Oxosilicat nicht innerhalb der ebenfalls rautenformigen Maschen dieser Schichten zu liegen, sondern in Blickrichtung [100] sowohl ober- als auch unterhalb der (Ho2)3+-Kationen. Ho2O[SiO4] and Ho2S[SiO4]: Two Chalcogenide Derivatives of Holmium(III) ortho-Oxosilicate Ho2O[SiO4] crystallizes monoclinically with the space group P21/c (a = 904.15(9), b = 688.93(7), c = 667.62(7) pm, β = 106.384(8)°, Z = 4) in the A-type structure of rare-earth(III) oxide oxosilicates. Yellow platelet-shaped single crystals were obtained as by-product during an experiment to synthesize Ho3Cl[SiO4]2 by reacting Ho2O3 and SiO2 in the ratio 4 : 6 with an excess of HoCl3 as flux at 1000 °C for seven days in evacuated silica ampoules. Both crystallographically different Ho3+ cations show coordination numbers of 8+1 and 7 with coordination figures of 2+1-fold capped trigonal prisms and octahedra, in which one of the vertices changes to an edge by two instead of one coordinating atoms, respectively. The O2— anion not linked to silicon is surrounded tetrahedrally by four Ho3+ cations which built a layer parallel (100) by vertex- and edge-sharing of the [OHo4]10+ units according to {[(O5)(Ho1)1/1(Ho2)3/3]4+}. Within rhombic meshes of these layers the isolated oxosilicate tetrahedra [SiO4]4— come to lie. Ho2S[SiO4] crystallizes orthorhombically in the space group Pbcm (a = 605.87(5), b = 690.41(6), c = 1064.95(9) pm, Z = 4). It also emerged as a single-crystalline by-product obtained during the synthesis of Ho2OS2 by reaction of a mixture of Ho2O3, Ho and S with the wall of the evacuated silica tube used as container with an excess of CsCl as flux at 800 °C. The structure of the yellow platelet-shaped, air and water resistant crystals also distinguishes two Ho3+ cations with bicapped trigonal prisms and trigondodecahedra as coordination polyhedra for CN = 8. The S2— anions are almost square planar surrounded by four Ho3+ cations, but situated completely outside this plane. The [SHo4]10+ squares form strongly corrugated layers perpendicular to [100] by corner-sharing according to {[(S)(Ho1)2/2(Ho2)2/2]4+}. Contrary to the oxide oxosilicates the isolated oxosilicate tetrahedra [SiO4]4— do not lie within the rhombic meshes of these layers, but above and below the (Ho2)3+ cations while viewing along [100].

K3Er7S12 und Rb3Er7S12: Zwei ternäre Erbium(III)-sulfide mit Kanalstruktur†

Die isotypen ternaren Erbium(III)-sulfide K3Er7S12 (a = 1185, 38(9); b = 2461, 5(2); c = 393, 59(3) pm) und Rb3Er7S12 (a = 1203, 51(9); b = 2483, 0(2); c = 394, 85(3) pm; beide orthorhombisch, Pnnm, Z = 2) bilden sich bei der Umsetzung von Erbium—Metall und Schwefel mit uberschussigem Alkalichlorid (KCl bzw. RbCl) als Flusmittel und Reaktand innerhalb von sieben Tagen bei 900 °C. Die stabchenformigen, gelben, transparenten Einkristalle zeichnen sich in ihrer Kristallstruktur durch ein Gerust aus ecken und kantenverknupften [ErS6]—Oktaedern (d(Er3+—S2—) = 265—285 pm) aus, in dessen entlang [001] verlaufenden Kanalen die Alkalimetall—Kationen (K+ bzw. Rb+; CN = 6 und 7 + 1) eingelagert sind. Unter Berucksichtigung der Ionenradienquotienten ri(A+)/ri(Ch2—) (A = K—Cs; Ch = S—Te) wird der Existenzbereich dieser Struktur vom Cs3Y7Se12—Typ diskutiert. K3Er7S12 and Rb3Er7S12: Two Ternary Erbium(III) Sulfides with Channel Structures The isotypic ternary erbium(III) sulfides K3Er7S12 (a = 1185.38(9), b = 2461.5(2), c = 393.59(3) pm) and Rb3Er7S12 (a = 1203.51(9), b = 2483.0(2), c = 394.85(3) pm; both orthorhombic, Pnnm, Z = 2) are obtained by reacting erbium metal and sulfur with an excess of alkali chloride (KCl or RbCl, respectively) serving as flux and reagent within seven days at 900 °C. The rod—shaped, yellow, transparent single crystals distinguish themselves in their crystal structure by a framework of corner— and edge—linked [ErS6] octahedra (d(Er3+—S2—) = 265—285 pm), in which the alkali metal cations (K+ and Rb+, respectively; CN = 6 and 7 + 1) are inserted into channels running along [001]. Under consideration of the ionic radius quotients ri(A+)/ri(Ch2—) (A = K—Cs, Ch = S—Te) the existence range of this Cs3Y7Se12—type of structure is discussed.