Rainer Pöttgen

Publications of Rainer Pöttgen

• Synthesis and Characterization of N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) Pincer Tin(IV) and Tin(II) Complexes.

  Authors: Jens Henning, Hartmut Schubert, Klaus Eichele, Florian Winter, Rainer Pöttgen, Hermann A Mayer, Lars Wesemann

  Inorganic chemistry. 04/2012;

  N-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-rayN-[2-P(i-Pr)(2)-4-methylphenyl](2)(-) (PNP) pincer complexes of tin(IV) and tin(II), [(PNP)SnCl(3)] (2) and [(PNP)SnN(SiMe(3))(2)] (3), respectively, were prepared and characterized by X-ray diffraction, solution and solid state NMR spectroscopy, and (119)Sn Mössbauer spectroscopy. Furthermore, (119)Sn cross polarization magic angle spinning NMR spectroscopic data of [Sn(NMe(2))(2)](2) are reported. Compound 2 is surprisingly stable toward air, but attempts to substitute chloride ligands caused decomposition.

• Structural characterization of the lithium silicides Li(15)Si(4), Li(13)Si(4), and Li(7)Si(3) using solid state NMR.

  Authors: Sven Dupke, Thorsten Langer, Rainer Pöttgen, Martin Winter, Stefano Passerini, Hellmut Eckert

  Physical chemistry chemical physics : PCCP. 03/2012;

  Local environments and lithium ion dynamics in the binary lithium silicides Li(15)Si(4), Li(13)Si(4), and Li(7)Si(3) have been characterized by detailed variable temperature static and magic-angleLocal environments and lithium ion dynamics in the binary lithium silicides Li(15)Si(4), Li(13)Si(4), and Li(7)Si(3) have been characterized by detailed variable temperature static and magic-angle spinning (MAS) NMR spectroscopic experiments. In the (6)Li MAS-NMR spectra, individual lithium sites are generally well-resolved at temperatures below 200 K, whereas at higher temperatures partial or complete site averaging is observed on the ms timescale. The NMR spectra also serve to monitor the phase transitions occurring in Li(7)Si(3) and Li(13)Si(4) at 235 K and 146 K, respectively. The observed lithium isotropic shift ranges of up to approximately 50 ppm indicate a significant amount of electronic charge stored on the lithium species, consistent with the expectation of the extended Zintl-Klemm-Busmann concept for the electronic structure of these materials. The (29)Si MAS-NMR spectra obtained on isotopically enriched samples, aided by double-quantum spectroscopy, are well suited for differentiating between the individual types of silicon sites within the silicon frameworks, and in Li(13)Si(4) their identification aids in the assignment of individual lithium sites via(29)Si{(7)Li} cross-polarization/heteronuclear correlation NMR. Variable temperature static (7)Li NMR spectra reveal motional narrowing effects, illustrating high lithium ionic mobilities in all of these compounds. Differences in the mobilities of individual lithium sites can be resolved by temperature dependent (6)Li MAS-NMR as well as (6)Li{(7)Li} rotational echo double resonance (REDOR) spectroscopy. For the compound Li(15)Si(4) the lithium mobility appears to be strongly geometrically restricted, which may result in a significant impediment for the use of Li-Si anodes for high-performance batteries. A comparison of all the (6)Li and (7)Li NMR spectroscopic data obtained for the three different lithium silicides and of Li(12)Si(7) previously studied suggests that lithium ions in the vicinity of silicon clusters or dimers have generally higher mobilities than those interacting with monomeric silicon atoms.

• Octahedral Pd(2+) Coordination and Ferromagnetic Ordering in Pd(S(2) O(7) ).

  Authors: Jörn Bruns, Matthias Eul, Rainer Pöttgen, Mathias S Wickleder

  Angewandte Chemie (International ed. in English). 12/2011;

  Oxidation of elemental palladium at elevated temperatures leads to the blue disulfate Pd(S(2) O(7) ) which has an octahedral, not the usual square-planar coordination of a Pd(2+) center. In theirOxidation of elemental palladium at elevated temperatures leads to the blue disulfate Pd(S(2) O(7) ) which has an octahedral, not the usual square-planar coordination of a Pd(2+) center. In their Communication (DOI: 10.1002/anie.201107197), M. S. Wickleder, R. Pöttgen, and co-workers show that this rare coordination leads to paramagnetic behavior and that ferromagnetic ordering occurs at low temperature. This is the first example for this phenomenon in an oxidic Pd(2+) compound.

• Octahedral pd(2+) coordination and ferromagnetic ordering in pd(s(2) o(7) ).

  Authors: Jörn Bruns, Matthias Eul, Rainer Pöttgen, Mathias S Wickleder

  Angewandte Chemie (International ed. in English). 11/2011; 51(9):2204-7.

  It's hip not to be square: The oxidation of elemental palladium with SO(3) leads to Pd(S(2) O(7) ) in which the Pd(2+) is in an octahedral coordination environment of oxygen atoms (see structureIt's hip not to be square: The oxidation of elemental palladium with SO(3) leads to Pd(S(2) O(7) ) in which the Pd(2+) is in an octahedral coordination environment of oxygen atoms (see structure Pd red, O blue, S yellow) and not the usual square-planar environment for Pd(2+) species. This unexpected geometry leads to the observed paramagnetism of the compound with ferromagnetic ordering at 11.7 K.

• Doped semimetal clusters: ternary, intermetalloid anions [Ln@Sn7Bi7]4- and [Ln@Sn4Bi9]4- (Ln = La, Ce) with adjustable magnetic properties.

  Authors: Felicitas Lips, Małgorzata Hołyńska, Rodolphe Clérac, Uwe Linne, Inga Schellenberg, Rainer Pöttgen, Florian Weigend, Stefanie Dehnen

  Journal of the American Chemical Society. 11/2011; 134(2):1181-91.

  Two K([2.2.2]crypt) salts of lanthanide-doped semimetal clusters were prepared, both of which contain at the same time two types of ternary intermetalloid anions, [Ln@Sn(7)Bi(7)](4-) andTwo K([2.2.2]crypt) salts of lanthanide-doped semimetal clusters were prepared, both of which contain at the same time two types of ternary intermetalloid anions, [Ln@Sn(7)Bi(7)](4-) and [Ln@Sn(4)Bi(9)](4-), in 0.70:0.30 (Ln = La) or 0.39:0.61 (Ln = Ce) ratios. The cluster shells represent nondeltahedral, fullerane-type arrangements of 14 or 13 main group metal atoms that embed the Ln(3+) cations. The assignment of formal +III oxidation states for the Ln sites was confirmed by means of magnetic measurements that reveal a diamagnetic La(III) compound and a paramagnetic Ce(III) analogue. Whereas the cluster anions with a 14-atomic main-group metal cage represent the second examples in addition to a related Eu(II) cluster published just recently, the 13-atomic cages exhibit a yet unprecedented enneahedral topology. In contrast to the larger cages, which accord to the Zintl-Klemm-Busmann electron number-structure correlation, the smaller clusters require a more profound interpretation of the bonding situation. Quantum chemical investigations served to shed light on these unusual complexes and showed significant narrowing of the HOMO-LUMO gap upon incorporation of Ce(3+) within the semimetal cages.

• Drastic change of the ferromagnetic properties of the ternary germanide GdTiGe through hydrogen insertion.

  Authors: Etienne Gaudin, Samir F Matar, Rainer Pöttgen, Matthias Eul, Bernard Chevalier

  Inorganic chemistry. 11/2011; 50(21):11046-54.

  Hydrogen absorption of the CeFeSi- and CeScSi-type forms of GdTiGe was performed. Before hydrogenation they show an antiferromagnetic transition at around 412 K and a ferromagnetic transition at 376Hydrogen absorption of the CeFeSi- and CeScSi-type forms of GdTiGe was performed. Before hydrogenation they show an antiferromagnetic transition at around 412 K and a ferromagnetic transition at 376 K, respectively. Hydrogenation of both forms leads to formation of the same hydride GdTiGeH which crystallizes with a filled CeScSi-type structure where all the [Gd(4)] tetrahedra are filled by hydrogen. This hydride is paramagnetic in the temperature range 4-300 K. The slightly negative value of the paramagnetic Curie temperature θ(p) confirms that all ferromagnetic interactions were destroyed in the case of the CeScSi-type form. From first-principles calculations with the PAW GGA methodology, the localization of hydrogen within the [Gd(4)] tetrahedra was confirmed through energetic stabilization. It was also seen that the energy changes significantly with volume, indicating the itinerant (delocalized) role of the electrons in the magnetism.

• Structural and dynamic characterization of Li(12)Si(7) and Li(12)Ge(7) using solid state NMR.

  Authors: Sven Dupke, Thorsten Langer, Rainer Pöttgen, Martin Winter, Hellmut Eckert

  Solid state nuclear magnetic resonance. 09/2011;

  Local environments and lithium ion dynamics in the binary lithium silicide Li(12)Si(7), and the analogous germanium compound have been characterized by detailed (6)Li, (7)Li, and (29)Si variableLocal environments and lithium ion dynamics in the binary lithium silicide Li(12)Si(7), and the analogous germanium compound have been characterized by detailed (6)Li, (7)Li, and (29)Si variable temperature static and magic-angle spinning (MAS) NMR experiments. In the MAS-NMR spectra, individual lithium sites are generally well-resolved at temperatures below 200K, whereas at higher temperatures partial site averaging is observed on the kHz timescale. The observed lithium chemical shift ranges of up to 60ppm indicate a significant amount of electronic charge stored on the lithium species, consistent with the expectation of the extended Zintl-Klemm-Bussmann concept used for the theoretical description of lithium silicides. Furthermore the strongly diamagnetic chemical shifts observed for the lithium ions situated directly above the five-membered Si(5) rings suggest the possibility of aromatic ring currents in these structural elements. This assignment is confirmed further by (29)Si{(7)Li} CPMAS-heteronuclear correlation experiments. The (29)Si MAS-NMR spectra of Li(12)Si(7), aided by 2-D J-resolved spectroscopy, are well suited for differentiating between the individual sites within the silicon framework, while further detailed connectivity information is available on the basis of 2-D INADEQUATE and radio frequency driven recoupling (RFDR) spectra. Variable temperature static (7)Li NMR spectra reveal the onset of strong motional narrowing effects, illustrating high lithium ionic mobilities in both of these compounds.

• Refined crystal structure and idealized structure of mixed-valent Eu4F5(CN2)2: transition possible.

  Authors: Leonid Unverfehrt, Markus Ströbele, Jochen Glaser, Thorsten Langer, Rolf-Dieter Hoffmann, Rainer Pöttgen, H-Jürgen Meyer

  Inorganic chemistry. 07/2011; 50(13):6010-8.

  The new europium fluoride carbodiimide Eu(4)F(5)(CN(2))(2) was synthesized by solid state reaction from mixtures of EuF(3) and Li(2)(CN(2)) at 700 °C. The crystal structure as refined by singleThe new europium fluoride carbodiimide Eu(4)F(5)(CN(2))(2) was synthesized by solid state reaction from mixtures of EuF(3) and Li(2)(CN(2)) at 700 °C. The crystal structure as refined by single crystal X-ray diffraction (P ̅42(1)c, no. 114, a = 16.053(1) Å, c = 6.5150(6) Å, Z = 8) reveals three crystallographically distinct [N═C═N](2-) ions in the structure of mixed-valent Eu(4)F(5)(CN(2))(2). The presence of one Eu(3+) and three Eu(2+) per formula unit Eu(4)F(5)(CN(2))(2) is confirmed by magnetic measurements and (151)Eu-Mössbauer spectroscopy. The arrangement of Eu ions and gravity centers of [NCN](2-) ions in the structure of Eu(4)F(5)(CN(2))(2) follow the motif formed by atoms in the CuAl(2)-type structure. A possible high-symmetry structure of Eu(4)F(5)(CN(2))(2) is discussed on the basis of a group-subgroup scheme.

• Ternary Antmonides RE2Ir3Sb4 (RE = La, Ce, Pr, Nd)

  Authors: Konrad Schäfer, Wilfried Hermes, Ute Ch. Rodewald, Rolf-Dieter Hoffmann, Rainer Pöttgen

  06/2011;

  The antimonides RE2Ir3Sb4 (RE = La, Ce, Pr, Nd) were synthesized by arc-melting of the elements and subsequent annealing or via high-frequence melting. The samples were characterized by X-ray powderThe antimonides RE2Ir3Sb4 (RE = La, Ce, Pr, Nd) were synthesized by arc-melting of the elements and subsequent annealing or via high-frequence melting. The samples were characterized by X-ray powder diffraction and the four structures were refined from sin-gle-crystal X-ray diffraction data: Pr2Ir3Sb4-type, Pnma, Z = 4, a = 1621.9(2), b = 458.60(8), c = 1099.8(1) pm, wR2 = 0.036, 1558 F2 values for La2Ir3Sb4, a = 1616.6(8), b = 456.5(2), c = 1094.8(5) pm, wR2 = 0.092, 1080 F2 values for Ce2Ir3Sb4, a = 1613.0(5), b = 454.9(2), c = 1094.1(5) pm, wR2 = 0.057, 1428 F2 values for Pr2Ir3Sb4, and a = 1609.8(6), b = 452.9(2), c = 1092.3(5) pm, wR2 = 0.052, 1472 F2 values for Nd2Ir3Sb4, with 56 parameters per refinement. The Sb1 atoms show enhanced displace-ment off the mirror planes at y = 1/4 and y = 3/4. A series of temperature dependent structure refinements of Pr2Ir3Sb4 down to 90 K are indicative of static disorder. The iridium and antimony atoms build up complex covalently bonded three-dimensional [Ir3Sb4] networks with Ir-Sb distances ranging from 256-269 pm (Nd2Ir3Sb4). The two crystallographically independent rare earth sites fill cavities of coordination numbers 17 (8 Ir + 9 Sb) and 15 (6 Ir + 9 Sb) within the [Ir3Sb4] polyanions. Temperature dependent magnetic susceptibility measurements indicate a stable trivalent ground state for the ce-rium compound. No magnetic ordering was evident down to 3 K.

• 1,1,1-Tris(distanna-closo-dodecaborate)stannate: a tripodal tin ligand.

  Authors: Claudia Nickl, Klaus Eichele, Dominik Joosten, Thorsten Langer, Falko M Schappacher, Rainer Pöttgen, Ulli Englert, Lars Wesemann

  Angewandte Chemie (International ed. in English). 06/2011; 50(25):5766-9.

• Surprising luminescent properties of the polyphosphates Ln(PO3)3:Eu (Ln = Y, Gd, Lu).

  Authors: Henning A Höppe, Karolina Kazmierczak, Sylwia Kacprzak, Inga Schellenberg, Rainer Pöttgen

  Dalton transactions (Cambridge, England : 2003). 06/2011; 40(39):9971-6.

  The optical emission properties of the lanthanoid catena-polyphosphates Ln(PO(3))(3) (Ln = Y, Gd, Lu) doped with europium were investigated. Incommensurately modulated β-Y(PO(3))(3):Eu (super spaceThe optical emission properties of the lanthanoid catena-polyphosphates Ln(PO(3))(3) (Ln = Y, Gd, Lu) doped with europium were investigated. Incommensurately modulated β-Y(PO(3))(3):Eu (super space group Cc (0|0.364|0)0) and Gd(PO(3))(3):Eu (space group I2/a) show the usual emission characteristics of Eu(3+), while in Lu(PO(3))(3):Eu (space group Cc) the europium is unprecedentedly partially reduced to the divalent state, as proven by both a broad emission band at 406 nm excited at 279 nm and an EPR spectroscopic investigation. (151)Eu-Mössbauer spectroscopy showed that only a very small part of the europium is reduced in Lu(PO(3))(3):Eu. An explanation for this unusual behaviour is given.

• Stannylene or metallastanna(IV)ocane: a matter of formalism.

  Authors: Erica Brendler, Erik Wächtler, Thomas Heine, Lyuben Zhechkov, Thorsten Langer, Rainer Pöttgen, Anthony F Hill, Jörg Wagler

  Angewandte Chemie (International ed. in English). 05/2011; 50(20):4696-700.

• P2(2-) and P(3-) units in the [Rh8P9]δ- polyanion of La4Rh8P9.

  Authors: Ulrike Pfannenschmidt, Dirk Johrendt, Frederik Behrends, Hellmut Eckert, Matthias Eul, Rainer Pöttgen

  Inorganic chemistry. 02/2011; 50(7):3044-51.

  The phosphide La(4)Rh(8)P(9) was synthesized from the elements in a bismuth flux. The structure was refined from single crystal diffractometer data: space group Cmcm, a = 1303.1(2), b = 1893.2(2), cThe phosphide La(4)Rh(8)P(9) was synthesized from the elements in a bismuth flux. The structure was refined from single crystal diffractometer data: space group Cmcm, a = 1303.1(2), b = 1893.2(2), c = 576.70(6) pm, wR2 = 0.0277, 1380 F(2) values, 65 variables. The rhodium and phosphorus atoms build up a three-dimensional [Rh(8)P(9)] polyanion which leaves larger cages for the three crystallographically independent lanthanum sites. The rhodium atoms have between four and six phosphorus neighbors at Rh-P distance ranging from 229 to 254 pm. Three of the four crystallographically independent phosphorus atoms are isolated (P(3-) units), while the P4 atoms form dimers with double bond character (208 pm P-P). The P(2)(2-) diphosphenide units bond side-on to a Rh3 and end-on to four Rh5 atoms. (31)P magic angle spinning (MAS) NMR spectroscopy is able to resolve three of the four crystallographically distinct phosphorus sites. The doubly bonded phosphorus site P4 is characterized by an axially symmetric shielding tensor of moderate anisotropy Δσ = σ(33) - σ(iso) = 257 ppm. Electronic band structure calculations prove the metallic character and reveal the significant difference between the isolated P(3-) and the phosphorus atoms of the P(2)(2-) units. Magnetic susceptibility measurement reveals Pauli paramagnetism.

• Homoleptic diphosphacyclobutadiene complexes [M($eta$(4)-P2C2R2)2]x- (M = Fe, Co; x = 0, 1).

  Authors: Robert Wolf, Andreas W. Ehlers, Marat M. Khusniyarov, Frantivsek Hartl, Bas Bruin de, Gary J. Long, Fernande Grandjean, Falko M. Schappacher, Rainer Pöttgen, Chris J. Slootweg, Martin Lutz, Anthony L. Spek, Koop Lammertsma

  Chemistry (Weinheim an der Bergstrasse, Germany). 12/2010; 16(48):14322-34.

  {The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds{The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)(2)][Fe($eta$(4)-P(2)C(2)tBu(2))(2)] (K1), [K([18]crown-6)(thf)(2)][Co($eta$(4)-P(2)C(2)tBu(2))(2)] (K2), and [K([18]crown-6)(thf)(2)][Co($eta$(4)-P(2)C(2)Ad(2))(2)] (K3

• Ylenes in the M(II)→Si(IV) (M=Si, Ge, Sn) coordination mode.

  Authors: Jörg Wagler, Erica Brendler, Thorsten Langer, Rainer Pöttgen, Thomas Heine, Lyuben Zhechkov

  Chemistry (Weinheim an der Bergstrasse, Germany). 12/2010; 16(45):13429-34.

  The reaction of the methimazolyl (mt, i.e., 2-mercapto-1-methylimidazolide) substituted silane Si(mt)(4) with SnCl(2) and GeCl(2) in dioxane affords the paddlewheel-shaped complexesThe reaction of the methimazolyl (mt, i.e., 2-mercapto-1-methylimidazolide) substituted silane Si(mt)(4) with SnCl(2) and GeCl(2) in dioxane affords the paddlewheel-shaped complexes [ClSi(μ-mt)(4)MCl] (M=Sn (1) and Ge (2), respectively). These compounds represent the first crystallographically characterized hexacoordinate silicon complexes comprising a Sn or Ge atom in the Si coordination sphere. An attempt to synthesize the related silicon compound 3 [ClSi(μ-mt)(4)SiCl] instead afforded the trisilane [ClSi(μ-mt)(4)Si-SiCl(3)] (3a), which provides the first crystallographic evidence for the feasibility of oligosilanes with adjacent hexacoordinate Si atoms. One of the hexacoordinate Si atoms of 3a features the unprecedented (Si(2)S(4))Si skeleton. Natural bonding orbital (NBO) analyses of compounds 1, 2, 3a (and the target compound 3) revealed characteristics of M(II)→Si(IV) (for 2 and 3) or M(I)→Si(IV) (for 3a) dative bonding in the systems with M=Si and Ge, whereas compound 1 exhibits a covalent Sn(III)-Si(III) bond.

• Homoleptic diphosphacyclobutadiene complexes [M(η(4)-P2C2R2)2]x- (M = Fe, Co; x = 0, 1).

  Authors: Robert Wolf, Andreas W Ehlers, Marat M Khusniyarov, František Hartl, Bas de Bruin, Gary J Long, Fernande Grandjean, Falko M Schappacher, Rainer Pöttgen, J Chris Slootweg, Martin Lutz, Anthony L Spek, Koop Lammertsma

  Chemistry (Weinheim an der Bergstrasse, Germany). 12/2010; 16(48):14322-34.

  The preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. CompoundsThe preparation and comprehensive characterization of a series of homoleptic sandwich complexes containing diphosphacyclobutadiene ligands are reported. Compounds [K([18]crown-6)(thf)(2)][Fe(η(4)-P(2)C(2)tBu(2))(2)] (K1), [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)tBu(2))(2)] (K2), and [K([18]crown-6)(thf)(2)][Co(η(4)-P(2)C(2)Ad(2))(2)] (K3, Ad = adamantyl) were obtained from reactions of [K([18]crown-6)(thf)(2)][M(η(4)-C(14)H(10))(2)] (M = Fe, Co) with tBuC[triple bond]P (1, 2), or with AdC[triple bond]P (3). Neutral sandwiches [M(η(4)-P(2)C(2)tBu(2))(2)] (4: M = Fe 5: M = Co) were obtained by oxidizing 1 and 2 with [Cp(2)Fe]PF(6). Cyclic voltammetry and spectro-electrochemistry indicate that the two [M(η(4)-P(2)C(2)tBu(2))(2)](-)/[M(η(4)-P(2)C(2)tBu(2))(2)] moieties can be reversibly interconverted by one electron oxidation and reduction, respectively. Complexes 1-5 were characterized by multinuclear NMR, EPR (1 and 5), UV/Vis, and Mössbauer spectroscopies (1 and 4), mass spectrometry (4 and 5), and microanalysis (1-3). The molecular structures of 1-5 were determined by using X-ray crystallography. Essentially D(2d)-symmetric structures were found for all five complexes, which show the two 1,3-diphosphacyclobutadiene rings in a staggered orientation. Density functional theory calculations revealed the importance of covalent metal-ligand π bonding in 1-5. Possible oxidation state assignments for the metal ions are discussed.

• Indium flux-growth of Eu2AuGe3: a new germanide with an AlB2 superstructure.

  Authors: C Peter Sebastian, Christos D Malliakas, Maria Chondroudi, Inga Schellenberg, Sudhindra Rayaprol, Rolf-Dieter Hoffmann, Rainer Pöttgen, Mercouri G Kanatzidis

  Inorganic chemistry. 10/2010; 49(20):9574-80.

  The germanide Eu(2)AuGe(3) was obtained as large single crystals in high yield from a reaction of the elements in liquid indium. At room temperature Eu(2)AuGe(3) crystallizes with the Ca(2)AgSi(3)The germanide Eu(2)AuGe(3) was obtained as large single crystals in high yield from a reaction of the elements in liquid indium. At room temperature Eu(2)AuGe(3) crystallizes with the Ca(2)AgSi(3) type, space group Fmmm, an ordered variant of the AlB(2) type: a = 857.7(4), b = 1485.5(10), c = 900.2(4) pm. The gold and germanium atoms build up slightly distorted graphite-like layers which consist of Ge(6) and Au(2)Ge(4) hexagons, leading to two different hexagonal-prismatic coordination environments for the europium atoms. Magnetic susceptibility data showed Curie-Weiss law behavior above 50 K and antiferromagnetic ordering at 11 K. The experimentally measured magnetic moment indicates divalent europium. The compound exhibits a distinct magnetic anisotropy based on single crystal measurements and at 5 K it shows a metamagnetic transition at ∼10 kOe. Electrical conductivity measurements show metallic behavior. The structural transition at 130 K observed in the single crystal data was very well supported by the conductivity measurements. (151)Eu Mössbauer spectroscopic data show an isomer shift of -11.24 mm/s at 77 K, supporting the divalent character of europium. In the magnetically ordered regime one observes superposition of two signals with hyperfine fields of 26.0 (89%) and 3.5 (11%) T, respectively, indicating differently ordered domains.

• Novel ternary alkaline-earth and rare-earth metal antimonides from gallium or indium flux. Synthesis, structural characterization and 121Sb and 151Eu Mössbauer spectroscopy of the series A7Ga8Sb8 (A = Sr, Ba, Eu) and Ba7In8Sb8.

  Authors: Svilen Bobev, Jonathan Hullmann, Thomas Harmening, Rainer Pöttgen

  Dalton transactions (Cambridge, England : 2003). 07/2010; 39(26):6049-55.

  Reported are the synthesis and the structural characterization of the new ternary antimonides Eu(7)Ga(8)Sb(8), Sr(7)Ga(8)Sb(8), Ba(7)Ga(8)Sb(8), and Ba(7)In(8)Sb(8). They have been synthesized fromReported are the synthesis and the structural characterization of the new ternary antimonides Eu(7)Ga(8)Sb(8), Sr(7)Ga(8)Sb(8), Ba(7)Ga(8)Sb(8), and Ba(7)In(8)Sb(8). They have been synthesized from reactions of the corresponding elements, using gallium or indium as metal fluxes. The four compounds are isostructural and crystallize with the space group P6(3)/mmc (no. 194) with lattice parameters as follows: a = 4.4942(8), c = 17.274(6) A for Eu(7)Ga(8)Sb(8); a = 4.5409(8), c = 17.486(4) A for Sr(7)Ga(8)Sb(8); a = 4.7045(12), c = 18.123(9) A for Ba(7)Ga(8)Sb(8); and a = 4.8274(3), c = 18.421(2) A for Ba(7)In(8)Sb(8). The temperature dependence of the magnetic susceptibility of Eu(7)Ga(8)Sb(8) confirms that the Eu ions are in the typical divalent state (Eu(2+)) with a room temperature effective magnetic moment mu(eff) = 8.02 mu(B). A phase transition from a paramagnetic to an antiferromagnetically ordered structure occurs in this material below 6 K. These results are corroborated by (151)Eu Mössbauer spectroscopy at 4.2 and 78 K, respectively. Eu(7)Ga(8)Sb(8), Ba(7)In(8)Sb(8) and the previously reported Sr(7)Ga(2)Sb(6) derivative of the cubic Th(3)P(4) type, were also investigated by (121)Sb Mössbauer spectroscopy.

• Synthesis and reactivity of ferrocenyl functionalized Sn/S cages.

  Authors: Christopher Pöhlker, Inga Schellenberg, Rainer Pöttgen, Stefanie Dehnen

  Chemical communications (Cambridge, England). 04/2010; 46(15):2605-7.

  Depending on the solvent used, the mono-stannylated FcSnCl(3) (1) reacts with Na(2)S to give ionic [Na(6)(Me(2)CO)(4)(OH(2))(6)] [(FcSn)(3)S(6)](2) (2), with a yet unprecedented thiostannate anion,Depending on the solvent used, the mono-stannylated FcSnCl(3) (1) reacts with Na(2)S to give ionic [Na(6)(Me(2)CO)(4)(OH(2))(6)] [(FcSn)(3)S(6)](2) (2), with a yet unprecedented thiostannate anion, or the adamantane-type Sn/S-cluster [(FcSn)(4)S(6)] (3). Complex 2 reacts readily with [Ni(acac)(2)], yielding the mixed-metallic complex [{Na(thf)(3.5)}(2){(FcSn)(8)Ni(3)S(16)}] x 2 THF (4 x 2 THF); the structures of 1-4 are discussed as well as Mössbauer spectra.

• Superconductivity in quasi one-dimensional carbides.

  Authors: Wolfgang Scherer, Christoph Hauf, Manuel Presnitz, Ernst-Wilhelm Scheidt, Georg Eickerling, Volker Eyert, Rolf-Dieter Hoffmann, Ute C Rodewald, Adrienne Hammerschmidt, Christian Vogt, Rainer Pöttgen

  Angewandte Chemie (International ed. in English). 02/2010; 49(9):1578-82.