bluuebunny/crossref_metadata_2025_split huggingface dataset:
KP544 amplifies the effects of nerve growth factor on cell differentiation and is neuroprotective
Authors: Fyfe James A. , Beauchamp Lilia M. , Caggiano Anthony O. , Price Raymond D. , Yamaji Takayuki , Matsuoka Nobuya , Krenitsky Thomas A. 
Published: October 2004

AbstractThe ability of endogenous neurotrophins, including nerve growth factor (NGF), to promote the survival and development of neurons provides convincing evidence for their therapeutic potential, despite significant barriers to their successful clinical use. Many of these barriers might be surmountable, however, by strategies that enhance endogenous neurotrophin signaling. We evaluated a series of substituted pyrimidines for their ability to enhance the effects of NGF. KP544 [2‐amino‐5‐(4‐chlorophenylethynyl)‐4‐(4‐trans‐hydroxycyclohexylamino) pyrimidine] amplified NGF‐induced neurite outgrowth of PC12 cells approximately 2‐fold at 2 µM. KP544 also enhanced choline acetyltransferase activity, a marker of differentiation induced by either NGF or by cyclic AMP, by 3‐ to 8‐fold, with a 2‐fold amplification at 0.12–0.3 µM. This amplification occurred at all concentrations of NGF used including those that maximally stimulated the cells. KP544 did not increase the levels of phosphorylated mitogen‐activated protein kinases (MAPK) above that seen with NGF alone. These studies suggested that KP544 functions within the cell at a site that is downstream from or independent of MAPK signaling. NGF‐induced neurite outgrowth in a human cell line (SH‐SY5Y neuroblastoma cells) was also enhanced with KP544 treatment. Primary embryonic rat cortical cultures were used to extend the observations beyond the studies with the immortalized cell lines. In addition to effects on neurite outgrowth, KP544 protected these cells from glutamate‐induced death. Overall, the data suggest that KP544 can selectively interact in the differentiation pathway downstream of MAPK in a manner that amplifies nerve growth factor and cyclic AMP effects and is also neuroprotective. Drug Dev. Res. 62:49–59, 2004. © 2004 Wiley‐Liss, Inc.
[Bis(amido)cyclodiphosph(III)azane]dichlorozirconium Complexes for Ethene Polymerization
Authors: Axenov Kirill V. , Klinga Martti , Leskelä Markku , Kotov Vasily , Repo Timo 
Published: October 2004

AbstractA series of new zirconium dichloride complexes bearing bulky cis‐bis(amino)cyclodiphosph(III)azane ligands, [(RN)2(tBuNP)2]ZrCl2 [R = phenyl (7), diphenylmethyl (8), 2,6‐diethylphenyl (9), 2,5‐di‐tert‐butylphenyl (10), and 2,6‐diisopropylphenyl (11)] were prepared in high yields by a two‐step synthetic route. The structure of cis‐[(Ph2CHN)(tBuNP)]2Zr(NMe2)2 (8a), determined by X‐ray analysis, shows that the zirconium atom has a distorted trigonal‐bipyramidal configuration consisting of four equidistant metal−amido nitrogen bonds and an additional coordination between the metal and a nitrogen atom from the cyclodiphosph(III)azane ring. After methylaluminoxane activation, these complexes exhibit moderate to high activities in ethene polymerization and produce high molar mass polyethene (Mw up to 1100 kg/mol). Polymerization experiments reveal that the behavior of bis(amido)cyclodiphosph(III)azane‐based ZrIV catalysts depends on the nature and steric bulkiness of the amido substituents, reaction temperature, MAO/zirconium ratio, as well as monomer pressure. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Cover Picture: Macromol. Rapid Commun. 20/2004
Authors: Wiesbrock Frank , Hoogenboom Richard , Schubert Ulrich S. 
Published: October 2004

Cover: The field of microwave‐assisted polymerizations is attracting continuously growing interest, additionally inspired by the introduction of single‐mode microwave reactors at the beginning of the millennium. This new class of reaction devices has overcome the safety uncertainties associated with domestic microwave ovens and has paved the way not only to an annually increasing number of publications, but also more sophisticated polymerizations. This review describes prominent examples of the polymerizations hitherto realized with microwave irradiation, including a critical account of the “microwave effects”.Further details can be found in the Review by F. Wiesbrock, R. Hoogenboom, and U. S. Schubert* on page 1739.
Complete assignment of 1H and 13C NMR spectra of some 4′‐substituted diethyl 1‐methylthio‐ and diethyl 1‐methylsulfonyl‐2‐oxo‐2‐phenylethylphosphonates
Authors: Reis Adriana Karla C. A. , Olivato Paulo R. , Rittner Roberto 
Published: October 2004

AbstractThe complete assignment of 1H and 13C NMR spectra of some 4′‐substituted diethyl 1‐methylthio‐ and diethyl 1‐methylsulfonyl‐2‐oxo‐2‐phenylethylphosphonates bearing as substituents methoxy, fluoro, chloro, bromo and nitro is reported. Copyright © 2004 John Wiley & Sons, Ltd.
Unusual presentation of infantile hemangioendothelioma
Authors: Bay Ali , Öner Ahmet Faik , Etlik Ömer , Koseoglu Burhan , Kaya Ali 
Published: October 2004

AbstractInfantile hemangioendothelioma is a rare benign hepatic tumor arising from mesenchymal tissue. Most of the cases present with congestive heart failure and asymptomatic abdominal mass were before 6 months of age. We described a patient with projectile vomiting, which is quite an unusual presentation. Following surgical resection, neither recurrence nor symptoms were seen in 2 years of follow‐up. © 2004 Wiley‐Liss, Inc.
Relative solvation and strength of polycyano‐ and polynitromethanes in water: a study with molecular dynamics simulations
Authors: Carrasco Nelson , González‐Nilo Fernando , Rezende Marcos Caroli 
Published: October 2004

AbstractThe long‐known saturation effect in the acidity of polynitromethanes as the number of electron‐withdrawing substituents is increased has no parallel in the polycyanomethane series, leading to a reversal in acidity when the two series are compared. A theoretical study based on molecular dynamics simulations was carried out, with a view to investigating the solvation patterns of all acidic polynitro‐ and polycyanomethanes and their conjugate bases in water. The results provide a qualitative interpretation of the causes of the saturation effect and the observed reversal in acidity. Copyright © 2004 John Wiley & Sons, Ltd.
Synthesis and characterization of soluble polyimides containing trifluoromethyl groups in their backbone
Authors: Kim Sang‐Uk , Lee Choonkeun , Sundar Saimani , Jang Wonbong , Yang Seung‐Jin , Han Haksoo 
Published: October 2004

AbstractA series of polyimides were synthesized from 2,2‐Bis(3,4‐dicarboxyphenyl)hexafluoropropane, 2,2‐bis(3‐amino‐4‐hydroxyphenyl)‐hexafluoropropane, and 4,4′‐oxydianiline by chemical imidization. The effects of the diamine ratios on the properties of the films were evaluated through the study of their thermal, electrical, and morphological properties. All the polymers exhibited better solubility in most of the organic solvents and hence were easily processable. Polyimides with more 2,2‐bis(3‐amino‐4‐hydroxyphenyl)‐hexafluoropropane exhibited better solubility and a low refractive index, which is highly desired for microelectronic applications. The dielectric constant and birefringence were strongly dependent on the fluorine content. With an increase in the fluorine substitution, both the dielectric constant and birefringence decreased. All the polymers exhibited high thermal stability (>400 °C). The absence of crystalline melting in differential scanning calorimetry and broad wide‐angle X‐ray diffraction patterns revealed the amorphous nature of the polymers, which was due to the presence of bulky CF3 groups and hinged ether linkages of the diamine component. The residual stress values decreased with an increase in the 4,4′‐oxydianiline content, and the results were in agreement with the dielectric constant. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4303–4312, 2004
Physical properties of glycosaminoglycan hydrogels
Authors: Kirker Kelly R. , Prestwich Glenn D. 
Published: October 2004

AbstractThe chemical composition of glycosaminoglycan (GAG) hydrogels was found to have a profound effect on the physical properties of gels. Hyaluronan (HA) and chondroitin sulfate (CS) were each modified with adipic dihydrazide (ADH) with carbodiimide chemistry. The resulting polymer was crosslinked with various concentrations of poly(ethylene glycol) dialdehyde (PEG‐diald) to produce a series of hydrogels. The physical properties of these GAG hydrogels varied in a concentration‐dependent fashion. Maximal crosslinking was observed at a theoretical crosslinking of 50% for the HA‐ADH‐PEG‐diald hydrogels and 75% for the CS‐ADH‐PEG‐diald hydrogels. Adding PEG‐diald beyond the optimum for crosslinking prolonged the in vitro enzymatic degradation time of the hydrogels. The swelling of the crosslinked GAG hydrogels was correlated with the amount of PEG‐diald used rather than with the crosslinking density. © 2004 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 42: 4344–4356, 2004
Recombination mechanisms in InAs/InP quantum dash lasers studied using high hydrostatic pressure
Authors: Marko I. P. , Sweeney S. J. , Adams A. R. , Jin S. R. , Murdin B. N. , Schwertberger R. , Somers A. , Reithmaier J. P. , Forchel A. 
Published: October 2004

AbstractTwo types of InAs quantum dash lasers grown on InP substrates with lasing wavelengths of 1.52 μm and 1.76 μm were studied. In both laser types the threshold current density, Jth, was about 2 kA/cm2 at room temperature and had a similar temperature sensitivity (T0 was about 80 K in the range T = 120–250 K, and T0 = 60–70 K from 250 to 300 K). Measurements of the spontaneous emission from a window milled in a substrate contact showed that Jrad, the radiative part of Jth, is almost temperature independent and less than 5% of Jth at T = 295 K, demonstrating that the relatively large value of Jth and its temperature sensitivity must be due to non‐radiative recombination processes. However, despite the similar temperature behaviour of the lasers, their pressure dependences were very different showing that in the 1.52 μm lasers, pressure independent defect related recombination outside the dashes due to thermal carrier spill‐over or thermal leakage dominates, while in the 1.76 μm quantum dash laser 60% of Jth is due to Auger recombination. (© 2004 WILEY‐VCH Verlag GmbH & Co. KGaA, Weinheim)
Dibismuthide Bi22‐: Synthesis and Crystal Structure of Bis[(1, 4, 7, 10, 13, 16‐Hexaoxacyclooctadecan)caesium]dibismuthide‐Ammonia (1/7) [Cs(18‐crown‐6)]2Bi2 · 7 NH3
Authors: Hanauer Tobias , Korber Nikolaus 
Published: October 2004

AbstractThe ammoniate [Cs(18‐crown‐6)]2Bi2 · 7 NH3 was prepared by solvating Cs5Bi4 together with an excess of 18‐crown‐6 in liquid ammonia. Single crystals were isolated and characterized by low temperature X‐ray structure analysis. [Cs(18‐crown‐6)]2Bi2 · 7 NH3 (C24H69Bi2Cs2N7O12) crystallizes in the space group P21/c with a = 10.1477(7) Å, b = 31.257(2) Å, c = 14.61(1) Å and β = 90.428(9)°. The compound contains a Bi22‐ anion with a short Bi‐Bi distance of 2.8635(4) Å. The anion coordinates side‐on to the central caesium cations of two [Cs(18‐crown‐6)]+ complexes, resulting in a neutral, molecular [Cs(18‐crown‐6)]2Bi2 complex.
Zur Kristallchemie der Oxoargentate und Silberoxometallate
Authors: Müller‐Buschbaum Hanskarl 
Published: October 2004

AbstractAg+ und Ag3+ zeigen in Festkörpern die unterschiedlichsten Koordinationspolyeder. In Analogie zu Oxocupraten, Oxoauraten, Oxoplatinaten usw. ist es üblich von Oxoargentaten zu sprechen. In den Oxoargentaten(I) und Oxoargentaten(III) sollte Ag+ hantelförmig bzw. Ag3+ quadratisch planar von O2‐ umgeben sein. Es wird gezeigt, daß diese Regel häufig durchbrochen wird. Eine Parallele zu den Oxocupraten besteht nur bedingt, da Silber beinahe unabhängig von seiner Valenz ein breites Spektrum an Koordinationssphären seitens Sauerstoff toleriert. Das Review zeigt O‐Ag‐O‐Polygone, deren Bindungswinkel von 180° bis 86° reichen. Bemerkenswert sind Verbindungen mit zwei verschiedenen hantelförmig koordinierten Metallatomen O‐M‐O (M = Ag und Hg). Erstaunlich sind die häufig beobachteten triangularen AgO3‐Polygone, die in vielen Fällen aber nicht von Silberatomen zentriert werden. Zwischen Oxoargentaten (Ag ist Bestandteil des anionischen Teils der Kristallstruktur) und Silber‐Oxometallaten (Ag ist Kation wie in klassischen Salzen) gibt es keine scharfe Trennung. In den Silber‐Oxometallaten zeigt Silber von den Alkalimetallen abweichende vielfältige Koordinationspolyeder, mit Koordinationszahlen C.N. = 3 bis C.N. = 12. Oxidische Verbindungen des Silbers mit Elementen mit freien Elektronenpaaren (Pb, Bi usw.) zeichnen sich durch einseitig offene Polyeder aus. Das freie Elektronenpaar (‘lone pair’) ist ergänzender Koordinationspartner und bildet gemeinsam mit Sauerstoff um diese Elemente geschlossene Polyeder. Ein freies Elektronenpaar kann aber auch die hantelförmige O‐Ag‐O‐Koordination zu einem quadratisch planaren [AgO2(lone pair)2]‐Polygon ergänzen.Von Martin Jansen, der die Oxochemie des Silbers wie kein zweiter Chemiker mit einer Fülle an Verbindungen und Synthesewegen bereichert hat, wird seit Jahren Silber die Fähigkeit zu d10‐d10‐Wechselwirkungen zugeschrieben. Mit steigendem Gehalt an Silber häufen sich die erstaunlich kurzen Ag‐Ag‐Abstände, um schließlich punktuell clusterähnliche Strukturen aufzubauen. In einigen Verbindungen (Ag2CuO3, Ag4Bi2O5, LiAg3O2, Ag5BiO4) sind eindimensionale Atomreihen [‐Ag‐Ag‐] mit Abständen dAg‐Ag < metallischer Abstand zu beobachten. Anisotrope elektrische Effekte sind zu erwarten. Bemerkenswert ist auch, daß sich die Bauprinzipen der Oxide des Silbers (Ag2O, AgO, Ag2O2, Ag2O3, Ag6O2) nur punktuell in Verbindungen des Silbers widerspiegeln.Ein häufig auftretendes Problem ist die Zuordnung von Sauerstoff an das zentrale Silberatom. Hierzu werden im Spektrum der Ag‐O‐Abstände breite Lücken oder eingeschobene Abstände zu anderen Metallatomen und nicht zuletzt Berechnungen effektiver Koordinationszahlen berücksichtigt. Dennoch ist eine zuverlässige Definition eines Ag/O‐Polyeders in vielen Fällen nicht möglich.
Low‐Temperature Oxidation of Ytterbium with Pyrrole in Liquid Ammonia. Formation of the First Unsubstituted Pyrrolates of a Rare Earth Element
Authors: Quitmann Catharina C. , Müller‐Buschbaum Klaus 
Published: October 2004

AbstractThe compounds [Yb2(Pyr)2(NH3)8][Yb(Pyr)5(NH3)] (1), [Yb(Pyr)3(PyrH)2(NH3)2] (2) and [Yb5(Pyr)12(NH3)4(NH2)]·2PyrH (3), (Pyr = pyrrolate anion, C4H4N‐; PyrH = pyrrole, C4H4NH) were obtained by the low‐temperature oxidation of ytterbium with the amine pyrrole in liquid ammonia. Single crystals of all three phases are formed next to each other, their yield depending on the temperature gradient of a subsequent thermal process in sealed glass ampoules. 1, 2 and 3 are the first unsubstituted pyrrolates of a rare earth element and display the decisive role of ammonia and the reaction conditions. The low temperature oxidation avoids polymerisation of the amine pyrrole. The crystal structures of 1, 2 and 3 exhibit units of different extension, different coordination spheres and oxidation states of ytterbium. The products were investigated by X‐ray single crystal diffraction, Mid IR and Far IR spectroscopy.
Structural and Magnetic Properties of the Double Perovskite LaCaMnNbO6
Authors: Bos Jan‐Willem G. , Attfield J. Paul 
Published: October 2004

AbstractThe structural and magnetic properties of the double perovskite LaCaMnNbO6 have been investigated using neutron powder diffraction and SQUID magnetometry. LaCaMnNbO6 has a monoclinic P21/n superstructure (a = 5.5929(1) Å, b = 5.7406(1) Å, c = 7.9824(1) Å and β = 89.897(1)°) with an almost fully ordered rocksalt arrangement of Mn and Nb over the perovskite B‐sites. Magnetisation measurements reveal a sharp antiferromagnetic transition at TN = 9 K. The low temperature antiferromagnetic ordering is described by a magnetic propagation vector of (0 1/2 1/2). Two collinear solutions are found for the magnetic structure.
Ternary Indides RE10Rh9±xIn20 (RE = Y, Tb‐Tm, Lu) and YbRhIn2 ‐ Syntheses and Crystal Chemical Peculiarities
Authors: Lukachuk Mar'yana , Rodewald Ute Ch. , Zaremba Vasy'l I. , Hoffmann Rolf‐Dieter , Pöttgen Rainer 
Published: October 2004

AbstractNew ternary indides RE10Rh9±xIn20 (RE = Y, Tb‐Tm, Lu) were synthesized from the elements by arc‐melting under argon and subsequent annealing in alumina or tantalum crucibles. YbRhIn2 was prepared in a sealed tantalum ampoule in an induction furnace. X‐ray powder and single crystal data for RE10Rh9+xIn20 revealed isotypy with the tetragonal Ho10Ni9In20 type structure, space group P4/nmm. A crystal of Tm10Rh9In20 shows the ideal composition: a = 1335.42(7), c = 921.26(6) pm, wR2 = 0.0524, 1460 F2 values and 62 variable parameters, while the RE10Rh9In20 indides with the lighter rare earth metals contain an additional rhodium site leading to a homogeneity range according to RE10Rh9±xIn20. This was manifested from X‐ray single crystal data for Y10Rh9.19(1)In20, Tb10Rh9.40(1)In20, Dy10Rh9.07(1)In20, Dy10Rh9.52(1)In20, Ho10Rh9.41(1)In20, and Er10Rh9.27(1)In20. On the other hand, defects were found for the Rh2 site of Lu10Rh8.87(1)In20. The crystal chemistry of the RE10Rh9In20 indides and the structurally related REPdIn2 indides with tetragonal HfNiGa2 structure is discussed. YbRhIn2 was synthesized in a sealed tantalum ampoule. It adopts the orthorhombic MgCuAl2 type structure: Cmcm, a = 418.24(6), b = 1024.0(2), c = 807.5(1) pm, wR2 = 0.0477, 292 F2 values and 16 variable parameters. The rhodium atoms fill distorted triangles of an orthorhombically distorted YbIn2 substructure.
Synthese und Kristallstrukturen von Ln(ClF2CCOO)3(H2O)3 (Ln = Gd, Dy, Ho, Er) und magnetisches Verhalten von Gd(ClF2CCOO)3(H2O)3
Authors: Rohde Alexander , Urland Werner 
Published: October 2004

AbstractEinkristalle von Ln(ClF2CCOO)3(H2O)3 (Ln = Gd, Dy, Ho, Er) wurden durch Reaktion von Ln2O3 mit einer wässrigen Lösung von ClF2CCOOH erhalten. Die Verbindungen sind isotyp miteinander und kristallisieren monoklin in der Raumgruppe P 21/c (Nr.: 14; Z = 4) mit den Gitterkonstanten, z.B. Gd(ClF2CCOO)3(H2O)3: a = 927, 9(3) pm, b = 1923, 8(4) pm, c = 1037, 2(4) pm, β = 114, 21(4)°. In den Kristallstrukturen sind die Lanthanidionen durch Carboxylatgruppen zu dimeren Einheiten verbrückt und von Sauerstoffatomen achtfach koordiniert. Das magnetische Verhalten von Gd(ClF2CCOO)3(H2O)3 wurde im Temperaturbereich von 1, 73 bis 300 K untersucht. Die magnetischen Daten weisen auf eine schwache antiferromagnetische Wechselwirkung in der dimeren Einheit hin.
Synthese und Struktur der Silber‐Komplexe [PPh4]2[Ag4Cl4(ClC6H4N3C6H4Cl)2], [Et4N][Ag2(tolyl‐N5‐tolyl)3]·2THF und [(n‐Bu)4N]3[Ag3I6] und über die Reaktion der Komplexe [Ag(ClC6H4N3C6H4Cl)]2 und [Ag(tolyl‐N5‐tolyl)]2 mit Iod
Authors: Barboza da Silva Carlos F. , Schwarz Simon , Galceran Mestres Montserrat , Strähle Joachim 
Published: October 2004

AbstractDer Silber‐Triazenido‐Komplex, [PPh4]2[Ag4Cl4(ClC6H4N3C6H4Cl)2] (1), entsteht bei der Umsetzung von Silber‐bis(p‐chlorphenyl)triazenid mit [PPh4]Cl in THF. Er kristallisiert monoklin in der Raumgruppe C2/c mit den Gitterkonstanten a = 2816, 9(3); b = 946, 67(7); c = 2552, 4(3) pm; β = 90, 22(1)° und Z = 4. Im zentrosymmetrischen Anion von 1 bilden die vier Ag‐Atome zusammen mit zwei Cl‐Atomen ein verzerrtes Oktaeder. Die äquatorial angeordneten Ag‐Atome werden von weiteren zwei Cl‐Atomen und zwei Triazenidoliganden überbrückt. Die Reaktion von [Et4N]Br mit Silber‐bis(p‐tolyl)pentaazadienid in THF ergibt den Komplex [Et4N][Ag2(tolyl‐N5‐tolyl)3] (2a). Die analoge Verbindung, [(n‐Bu)4N][Ag2(tolyl‐N5‐tolyl)3] (2b) wird auch bei der Umsetzung von [(n‐Bu)4N]I mit Silber‐bis(p‐tolyl)pentaazadienid in THF bei Verwendung eines dreifachen Überschusses des Pentaazadienids erhalten. Wenn gleiche Anteile an [(n‐Bu)4N]I und Silberpentaazadienid eingesetzt werden, entsteht jedoch der Komplex [(n‐Bu)4N]3[Ag3I6] (3). Von 2a werden trikline Kristalle der Zusammensetzung 2a·2THF mit der Raumgruppe P{\bar 1} und a = 1303, 6(3); b = 1471, 3(4); c = 1811, 6(2) pm; α = 98, 51(2)°; β = 93, 33(2)°; γ = 112, 50(2)° und Z = 2 erhalten. Im Anion der Verbindungen 2a und 2b verbrücken drei Pentaazadienidoliganden mit ihren Atomen N1 und N3 zwei Ag‐Atome. Ein Ag‐Atom wird zusätzlich von den Atomen N5 zweier Liganden koordiniert, so daß sich für die Ag‐Atome eine unterschiedliche Koordination in Form einer trigonal‐planaren bzw. einer verzerrt quadratisch‐pyramidalen Anordnung ergibt. 3 bildet orthorhombische Kristalle mit der Raumgruppe Pca21 und a = 1675, 0(6); b = 1698, 8(2); c = 2612, 8(5) pm und Z = 4. Das Anion [Ag3I6]3‐ wird von drei über gemeinsame Flächen verknüpften AgI4‐Tetraedern gebildet. Bei der Umsetzung der Silbertriazenido‐ und ‐pentaazadienido‐Komplexe [Ag(ClC6H4N3C6H4Cl)]2 und [Ag(tolyl‐N5‐tolyl)]2 mit I2 werden diese zu den Azoverbindungen, [ClC6H4N=NC6H4Cl] (4) und [tolyl‐N=N‐tolyl] (5) sowie N2 oxidiert.
Pr3Se2SiN3: Das erste Nitrido‐cyclo‐Trisilicat mit diskreten [Si3N9]15‐‐Anionen gemäß Pr9Se6[Si3N9]
Authors: Lissner Falk , Schleid Thomas 
Published: October 2004

AbstractBei Versuchen zur Darstellung von Nitridseleniden des Praseodyms erhält man durch Oxidation von Praseodymmetall mit Selen und Natriumazid sowie Beimengungen von Praseodymtrichlorid und Natriumchlorid als Flußmittel in evakuierten Kieselglasampullen bei 900 °C innerhalb von sieben Tagen unter Mitwirkung des Behältermaterials (SiO2) dunkelgelbe Stäbchen eines anionisch derivatisierten Nitrido‐cyclo‐Trisilicats des dreiwertigen Praseodyms der Zusammensetzung Pr3Se2SiN3, besser Pr9Se6[Si3N9] (a = 1892, 41(9), c = 1037, 25(6) pm; trigonal, $R{\bar 3}$, Z = 6), als Nebenprodukt. Die Kristallstruktur enthält drei kristallographisch unterschiedliche Pr3+‐Kationen, von denen zwei je siebenfach und das dritte achtfach von zwei verschiedenen Se2‐‐ bzw. drei unabhängigen N3‐‐Anionen koordiniert werden. Als strukturelles Hauptmerkmal treten jedoch diskrete Nitrido‐cyclo‐Trisilicat‐Einheiten [Si3N9]15‐ in den Vordergrund, deren sechsringförmiger Aufbau durch Eckenverknüpfung dreier [SiN4]8‐‐Tetraeder (d(Si‐N) = 172‐179 pm; ∢(N‐Si‐N) = 101‐116°; ∢(Si‐N‐Si) = 117°) realisiert ist.
Monomere und polymere Komplexe mit Ni‐CN‐Ni‐ und Pt‐CN‐Ni‐Verknüpfungen
Authors: Flay Marie‐Louise , Vahrenkamp Heinrich 
Published: October 2004

AbstractDie Anbindung der Baueinheit Ni(Me6tren)2+ an Ni(CN)42‐ und Pt(CN)42‐ liefert die Dreikernkomplexe [(Me6tren)Ni‐NC‐M(CN)2‐CN‐Ni(Me6tren)](ClO4)2 mit M = Ni und Pt. Der Einsatz der sterisch weniger anspruchsvollen Baueinheit Ni(tren)2+ führt zu den Koordinationspolymeren [M(μ‐CN)4{Ni(tren)}2](ClO4)2 mit M = Ni und Pt. In diesen liegen dreisträngige Bänder mit zentralen M(CN)4‐ und peripheren (tren)Ni(NC)2‐Verknüpfungseinheiten vor.
Über die Antimonidoxide La9Sb5O5 und Ce9Sb5O5 sowie die binären Phasen La2Sb und Ce2Sb
Authors: Nuss Jürgen , von Schnering Hans Georg , Grin Yuri 
Published: October 2004

AbstractDie neuen Antimonidoxide La9Sb5O5 und Ce9Sb5O5 wurden aus Sb2O3, Antimon und Seltenerdmetall (La, Ce) in geschlossenen Tantalampullen bei 1770 K dargestellt. Die luft‐ und feuchtigkeitsempfindlichen Seltenerdmetallverbindungen bilden schwarze, im Auflicht metallisch glänzende, würfelförmige Kristalle. Sie kristallisieren in einem neuen Strukturtyp (Pearson‐Symbol tP38; Raumgruppe P4/n, Nr. 85; La9Sb5O5: a = 1041.5, c = 934.0 pm; Ce9Sb5O5: a = 1029.7, c = 922.8 pm; Z = 2), eine Defektvariante der Sc2Sb‐Struktur, aufgefüllt mit Sauerstoffatomen: Sc10Sb5□5 ≙ La9□Sb5O5 bzw. Ce9□Sb5O5. La9Sb5O5 zeigt metallische Leitfähigkeit mit ρ = 6.7 mΩ·cm bei 293 K. Des Weiteren wurden die binären Phasen La2Sb und Ce2Sb nochmals untersucht. Es zeigte sich, dass diese Phasen auch in Gegenwart von Sauerstoff entstehen.