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  • Articles: DFG German National Licenses  (17)
  • Inorganic Chemistry  (15)
  • Low calcium  (2)
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  • Articles: DFG German National Licenses  (17)
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  • 1
    ISSN: 1432-1912
    Keywords: Key words High potassium ; Ictaform events ; Low calcium ; Low magnesium ; Methysticin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract  Methysticin is one of the constituents of Piper methysticum which possesses anticonvulsant and neuroprotective properties. Its effects on different in vitro seizure models were tested using extracellular recordings in rat temporal cortex slices containing the hippocampus and the entorhinal cortex. Elevating [K+]0 induced seizure-like events with tonic and clonic electrographic phases in area CA1. Lowering [Ca2+]0 caused recurrent seizure like episodes with large negative field potential shifts. Lowering Mg2+ induced short recurrent discharges in area CA3 and CA1 while ictaform events lasting for many seconds were induced in the subiculum, entorhinal and temporal neocortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the subiculum, entorhinal and temporal cortex changed their characteristics after one to two hours to late recurrent discharges. In a concentration-range from 10 to 100 μM methysticin reversibly blocked all these types of epileptiform activity. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum or the alveus remained almost unaffected by methysticin. A paired pulse stimulus paradigm used to test for effects of methysticin on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the responses to a paired pulse stimulus to stratum radiatum were depressed over the whole range of tested stimulus intervals. The findings suggest that methysticin has effects on different patterns of epileptiform activity possibly by interfering with processes responsible for frequency potentiation.
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  • 2
    ISSN: 1432-1912
    Keywords: High potassium ; Ictaform events ; Low calcium ; Low magnesium ; Methysticin
    Source: Springer Online Journal Archives 1860-2000
    Topics: Medicine
    Notes: Abstract Methysticin is one of the constituents of Piper methysticum which possesses anticonvulsant and neuroprotective properties. Its effects on different in vitro seizure models were tested using extracellular recordings in rat temporal cortex slices containing the hippocampus and the entorhinal cortex. Elevating [K+]o0 induced seizure-like events with tonic and clonic electrographic phases in area CA1. Lowering [Ca2+]0 caused recurrent seizure like episodes with large negative field potential shifts. Lowering Mg2+ induced short recurrent discharges in area CA3 and CA1 while ictaform events lasting for many seconds were induced in the subiculum, entorhinal and temporal neocortex. In the hippocampus the activity stayed stable over a number of hours. In contrast, the ictaform events in the subiculum, entorhinal and temporal cortex changed their characteristics after one to two hours to late recurrent discharges. In a concentration-range from 10 to 100 μM methysticin reversibly blocked all these types of epileptiform activity. Decreases in [Ca2+]0 and associated slow field potentials evoked by repetitive stimulation of the stratum radiatum or the alveus remained almost unaffected by methysticin. A paired pulse stimulus paradigm used to test for effects of methysticin on synaptically evoked transient field potentials in normal medium revealed interference with mechanisms involved in frequency potentiation. While responses to alvear stimulation were largely unaffected, the responses to a paired pulse stimulus to stratum radiatum were depressed over the whole range of tested stimulus intervals. The findings suggest that methysticin has effects on different patterns of epileptiform activity possibly by interfering with processes responsible for frequency potentiation.
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  • 3
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 627-629 
    ISSN: 0044-2313
    Keywords: Ternary metal selenides ; crystal structure ; MAPLE ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Preparation and Crystal Structure of Rb2Ni3Se4The compound Rb2Ni3Se4 was synthesized by heating a mixture of rubidium carbonate, nickel and selenium at 850°C in an atmosphere of hydrogen. The compound has a golden lustre and crystallizes with the K2Pd3S4-type structure; a = 10.555(3) Å, b = 27.588(6) Å, c = 6.031(6) Å, Z = 8, Fddd (No. 70).The structure can be described as a stacking of layers of the composition Rb2Ni3Se4 with a stacking sequence abcd. The electrostatic part of lattice energy (MAPLE) will be discussed for compounds of the compositions A2M3X4 (A K, Rb, Cs; M Ni, Pd, Pt and X S, Se).
    Notes: Die Darstellung von Rb2Ni3Se4 gelang durch Umsetzung von Rubidiumcarbonat, Nickel und Selen in einem Wasserstoffstrom bei 850°C. Die goldfarbig glänzende Verbindung kristallisiert im K2Pd3S4-Typ; a = 10,555(3) Å, b = 27,588(6) Å, c = 6,031(6) Å, Z = 8, Fddd (Nr. 70).Die Struktur läßt sich als Stapelung von Schichten der Zusammensetzung Rb2Ni3Se4 mit der Stapelfolge abcd beschreiben. Der elektrostatische Anteil der Gitterenergie (MAPLE) wird für Verbindungen des Typs A2M3X4 (mit A K, Rb, Cs; M Ni, Pd, Pt und X S, Se) diskutiert.
    Additional Material: 2 Ill.
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  • 4
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 597 (1991), S. 27-32 
    ISSN: 0044-2313
    Keywords: Ternary chalcogenides A2M3X4 (A ≙ alkali metal; M ≙ Ni, Pt, Pd; X ≙ S, Se) crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Layered Structures of Ternary Chalcogenides A2M3X4 (A ≙ K, Rb, Cs; M ≙ Ni, Pd, Pt; X ≙ S, Se)The ternary chalcogenides A2M3X4 have been prepared by fusion reactions of alkali carbonates with metals M ≙ Ni, Pd or Pt and the chalcogens X ≙ S or Se. Alternatively, the chalcogenides could be synthesized from alkali carbonates and M in a stream of hydrogen charged with chalcogen. X-ray investigations on powdered samples and single crystals reveal layered structures in which neutral A2M3X4-slabs from stacking variants.
    Notes: Die Synthese ternärer Chalkogenide A2M3X4 gelang über Schmelzreaktionen durch Umsetzungen von Alkalimetallcarbonaten mit den Metallen M ≙ Ni, Pd oder Pt und den Chalkogenen X ≙ S oder Se oder über eine Reaktion der beiden erstgenannten Komponenten in einem mit Chalkogen beladenen Wasserstoffstrom.Röntgenographische Untersuchungen an pulverförmigen Proben sowie an Einkristallen führten zu Schichtstrukturen, in denen neutrale A2M3X4-Schichtpakete Stapelvarianten erzeugen.
    Additional Material: 2 Ill.
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  • 5
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 2015-2020 
    ISSN: 0044-2313
    Keywords: Cluster compounds ; technetium ; rhenium ; preparation ; crystal structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Isolated [M6S14] Units in Ternary Sulfides of Technetium and RheniumWe have successfully prepared the ternary sulfides Rb10Tc6S14, Cs10Tc6S14, Rb10Re6S14, and Cs10Re6S14 by heating alkali carbonate with elemental technetium or rhenium in a hydrogen stream charged with sulfur.Structural investigations on single crystals revealed that these compounds crystallize in the space group Fm3m. [M6S14] cluster units (M \documentclass{article}\pagestyle{empty}\begin{document}$ \hat = $\end{document} Tc, Re) are found as the characteristic structural features, in which regular M6 octahedra are coordinated by sulfur atoms over their eight faces and six vertices. Other than in the case of the previously investigated ternary technetium and rhenium chalcogenides, these units are not linked to one another, but occur as isolated complex anions which form a cubic close packed array. The alkali ions, whose sites are partly statistically occupied, are found on the corners, the edges and the longer face diagonals of a rhombic dodecahedron surrounding each of these units. The dodecahedra share all their faces with one another.The diamagnetic behaviour which was measured on Cs10Tc6S14 in the temperature range from 10 to 295 K is in accordance with a 24-electron-configuration of the regular M6 octahedra.
    Notes: Durch Schmelzreaktionen von Alkalicarbonat mit elementarem Technetium oder Rhenium in einem mit Schwefel beladenen Wasserstoffstrom gelang die Darstellung der ternären Sulfide Rb10Tc6S14, Cs10Tc6S14, Rb10Re6S14 und Cs10Re6S14.Strukturuntersuchungen an Einkristallen ergaben, daß diese Verbindungen isotyp in der Raumgruppe Fm3m kristallisieren. Als charakteristische Strukturelemente treten [M6S14]-Baueinheiten (M \documentclass{article}\pagestyle{empty}\begin{document}$ \hat = $\end{document} Tc, Re) auf, in denen die unverzerrten M6-Oktaeder über den acht Flächen und sechs Ecken von Schwefelatomen koordiniert sind. Diese Einheiten sind, anders als bei den bisher untersuchten ternären Technetium- und Rheniumchalcogeniden, nicht untereinander verknüpft, sondern liegen als isolierte komplexe Anionen vor, die sich entsprechend einer kubisch dichten Kugelpackung anordnen. Die Alkalimetallionen befinden sich mit teilweise statistischer Besetzung ihrer Punktlagen auf den Ecken, den Kanten und den längeren Flächendiagonalen eines jede dieser Einheiten umgebenden Rhombendodekaeders. Die Dodekaeder sind untereinander allseitig flächenverknüpft.Der an Cs10Tc6S14 im Temperaturbereich zwischen 10 und 295 K gemessene Diamagnetismus stimmt mit der Annahme einer 24-Elektronenkonfiguration der regulären M6-Oktaeder überein.
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  • 6
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 553 (1987), S. 248-260 
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: On the Crystal Chemistry of Some Alkali Thiomanganates and -zincates. With a Remark on the ThCr2Si2-TypeNew quaternary sulfides ALiMS2 (A ≙ K, Rb, Cs and M ≙ Mn, Zn) were synthesized by a reaction of alkali carbonates with manganese and zinc, respectively, in a stream of H2S at 800°C. Single crystal X-ray investigations revealed the structures of KLiMnS2 and KLiZnS2.All compounds are isotypic and crystallize in the BaZn2P2-structure type. The atomic arrangements are treated as nine spheres close packings of sulfur atoms filled with cations. Criteria are given to distinguish the BaZn2P2-structure type from the ThCr2Si2-structure type.
    Notes: Erstmals dargestellt wurden die quaternären Sulfide ALiMS2 (A ≙ K, Rb, Cs und M ≙ Mn, Zn) durch Umsetzung der Alkalicarbonate mit Mangan bzw. Zink im H2S-Strom bei 800°C. Die Strukturen von KLiMnS2 und KLiZnS2 wurden an Einkristallen bestimmt.Alle Verbindungen sind isotyp und kristallisieren im BaZn2P2-Typ. Die Strukturen werden diskutiert als mit Kationen aufgefüllte Neunerkugelpackungen der Schwefelatome. Es werden Kriterien angegeben, die eine Unterscheidung der Strukturtypen BaZn2P2 und ThCr2Si2 erlauben.
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  • 7
    ISSN: 0044-2313
    Keywords: Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Cs4Re6S13 and Cs4Re6S13.5  -  Two Compounds with [Re6S8] Clusters Slightly Differing as to their Framework StructuresCs4Re6S13 was synthesized by the reaction of cesium carbonate with rhenium at 800°C in an argon atmosphere charged with sulphur. The preparation of Cs4Re6S13.5 succeeded by an analogous procedure using a stream of H2S.Structural investigations on single crystals revealed atomic arrangements in which [Re6S8] clusters are linked threedimensionally by Sn2- bridges. In the compound Cs4Re6S13 \documentclass{article}\pagestyle{empty}\begin{document}$\buildrel \wedge \over =$\end{document} Cs4[Re6S8]S2/2(S2)4/2 the rhenium atoms of adjacent Re6-octahedra are connected by sulphide and disulphide bridges in a ratio of 1:2. In the compound Cs4Re6S13.5 \documentclass{article}\pagestyle{empty}\begin{document}$\buildrel \wedge \over =$\end{document} Cs4[Re6S8]S2/2(S2)3/2(S3)1/2 one disulphide bridge is replaced by one trisulphide bridge.The nearly regular Re6-octahedra correspond with a diamagnetic 24-electron configuration.
    Notes: Cs4Re6S13 wurde durch Umsetzung von Caesiumcarbonat mit Rhenium in einem mit Schwefel beladenen Argonstrom bei 800°C erhalten. Cs4Re6S13,5 konnte nach einem analogen Verfahren im Schwefelwasserstoffstrom synthetisiert werden.Strukturuntersuchungen an Einkristallen führten zu Atomanordnungen, in denen [Re6S8]-Baueinheiten über Sn2--Brücken dreidimensional zu Gerüststrukturen verknüpft sind. Im Cs4Re6S13 \documentclass{article}\pagestyle{empty}\begin{document}$\buildrel \wedge \over =$\end{document} Cs4[Re6S8]S2/2(S2)4/2 werden die Rheniumatome benachbarter Re6-Oktaeder über Sulfid- und Disulfidbrücken im Verhältnis 1:2 miteinander verbunden, im Cs4Re6S13,5 \documentclass{article}\pagestyle{empty}\begin{document}$\buildrel \wedge \over =$\end{document} Cs4[Re6S8]S2/2(S2)3/2(S3)1/2 ist eine Disulfidbrücke durch eine Trisulfidbrücke ersetzt.Die nahezu regulären Re6-Oktaeder sind in Übereinstimmung mit dem unmagnetischen 24-Valenzelektronenzustand.
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  • 8
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 619 (1993), S. 243-252 
    ISSN: 0044-2313
    Keywords: Alkali metal chromium chalcogenides ; crystal structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: New Alkali Metal Chromium Chalcogenides and their Structural ClassificationThe compounds RbCr3S5, K3Cr11S18, RbCr5Se8 and CsCr5Se8 could be obtained in the form of wellshaped crystals via fusion reactions of the alkali metal carbonates with chromium and the corresponding chalcogen. The compounds crystallize in the monoclinic space groups C2/m (RbCr3S5: a = 19.372(3) Å, b = 3.498(1) Å, c = 12.119(2) Å, β = 122.78(1)°, Z = 4; K3Cr11S18: a = 41.876(3) Å, b = 3.463(1) Å, c = 16.315(3) Å, β = 150.07(1)°, Z = 2; RbCr5Se8: a = 18.737(2) Å, b = 3.623(1) Å; c = 9.016(1) Å, β = 104.65(1)°, Z = 2; CsCr5Se8: a = 18.795(2) Å, b = 3.637(1) Å, c = 9.104(1) Å, β = 104.52(1)°, Z = 2).We propose a structure classification from group-subgroup-relations.MAPLE calculations reveal that the reactions of the binary chalcogenides to yield the ternary compounds are exothermic in each case and are dependent on the chromium/alkali metal ratio in the ternary chalcogenides.
    Notes: Durch Umsetzungen der Alkalimetallcarbonate mit Chrom und dem entsprechenden Chalkogen in der Schmelze konnten die Verbindungen RbCr3S5, K3Cr11S18, RbCr5Se8 und CsCr5Se8 als gut ausgebildete Kristalle erhalten werden. Die Verbindungen kristallisieren monoklin im Raumgruppentyp C2/m (RbCr3S5: a = 19,372(3) Å, b = 3,498(1) Å, c = 12,119(2) Å, β = 122,78(1)°, Z = 4; K3Cr11S18: a = 41,876(3) Å, b = 3,463(1) Å, c = 16,315(3) Å, β = 150,07(1)°, Z = 2; RbCr5Se8: a = 18,737(2) Å, b = 3,623(1) Å; c = 9,016(1) Å, β = 104,65(1)°, Z = 2; CsCr5Se8: a = 18,795(2) Å, b = 3,637(1) Å, c = 9,104(1) Å, β = 104,52(1)°, Z = 2).Über Gruppe-Untergruppe-Beziehungen wird eine Struktursystematik vorgeschlagen.MAPLE-Rechnungen zeigen, daß die Reaktionen der binären Chalkogenide zu den ternären Verbindungen jeweils exotherm sind und vom Verhältnis Chrom/Alkalimetall in den ternären Chalkogeniden abhängen.
    Additional Material: 8 Ill.
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  • 9
    ISSN: 0044-2313
    Keywords: Ternary cobalt sulphides ; preparation ; crystal structure ; magnetic properties ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: A New Type of Ternary Cobalt Sulphide, A9Co2S7 (A \documentclass{article}\pagestyle{empty}\begin{document}$ \buildrel \wedge \over = $\end{document} K, Rb or Cs), containing Trigonal-Planar [CoS3] Units of Two- and Three-Valent CobaltThe passage of a stream of hydrogen over an alkali carbonate/cobalt/sulphur melt resulted in the preparation of the compounds K9Co2S7, Rb9Co2S7 and Cs9Co2S7. The structure of the potassium compound (Space group P213, Z = 4) could be determined from X-ray diffraction experiments on single crystals whilst X-ray investigations of powdered samples of the rubidium and caesium compounds indicate isotypic atomic arrangements with K9Co2S7. The characteristic structural elements of these compounds are trigonal-planar [CoS3]-units of two- and three-valent cobalt. The results from investigations of the magnetic properties of these ternary cobalt sulphides are in agreement with those expected for mixed-valent CoII/CoIII structures. The analogously-composed ferrates are closely structurally-related to these sulphides and show corresponding magnetic properties [1].
    Notes: Durch Schmelzreaktionen von Alkalicarbonat mit Cobalt und Schwefel im Wasserstoffstrom gelang die Darstellung der Verbindungen K9Co2S7, Rb9Co2S7 und Cs9Co2S7. Die Struktur der Kaliumverbindung konnte über röntgenographische Untersuchungen an Einkristallen bestimmt werden (Raumgruppe P213, Z = 4). Untersuchungen an pulverförmigen Proben lassen für die Rubidium- und die Cäsiumverbindung isotype Atomanordnungen erkennen. Als charakteristische Strukturelemente treten trigonal planare [CoS3]-Baugruppen des zwei- und dreiwertigen Cobalts auf. Untersuchungen zum Magnetismus sind in Übereinstimmung mit der Annahme eines gemischtvalenten Aufbaus, der auch bei den analog zusammengesetzten, in einem eng verwandten Strukturtyp kristallisierenden Ferraten auftritt [1].
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  • 10
    ISSN: 0044-2313
    Keywords: Alkali metal manganese selenides ; alkali metal manganese tellurides ; crystal structure ; spin structure ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Alkali Metal Manganese Selenides and Tellurides - Synthesis, Crystal and Spin StructuresThe compounds Rb2Mn3Se4, Cs2Mn3Se4, Rb2Mn3Te4 and Cs2Mn3Te4 were synthesized by the reaction of alkali metal carbonates with chalcogen and Mn or MnCO3 in a stream of hydrogen charged with chalcogen.Structural investigations show that all compounds crystallize in isotypic atomic arrangements (Cs2Mn3S4-type, space group Ibam, Z = 4). Additionally neutron diffraction experiments were carried out and yielded the spin structures of Rb2Mn3Se4 and Cs2Mn3Se4 (Shubnikov space group Ibam').The structural related selenides ALiMnSe2 and ALiZnSe2 (A = K, Rb or Cs) were synthesized by analogous reactions. All these compounds are isotypic and crystallize in the BaZn2P2-structure type.
    Notes: Die Verbindungen Rb2Mn3Se4, Cs2Mn3Se4, Rb2Mn3Te4 und Cs2Mn3Te4 wurden durch Umsetzungen von Alkalimetallcarbonaten mit Mangan oder Mangancarbonat und Chalkogen in einem mit Chalkogen beladenen Wasserstoffstrom erhalten.Kristallstrukturuntersuchungen ergaben, daß alle Verbindungen isotyp kristallisieren (Cs2Mn3S4-Typ, Raumgruppe Ibam, Z = 4). Neutronenbeugungsuntersuchungen ermöglichten darüber hinaus die Bestimmung der antiferromagnetischen Spinstrukturen von Rb2Mn3Se4 und Cs2Mn3Se4 (Shubnikov-Raumgruppe Ibam').Die strukturverwandten Selenide ALiMnSe2 und ALiZnSe2 mit A = K, Rb oder Cs wurden über analoge Umsetzungen synthetisiert. Sie kristallisieren alle im BaZn2P2-Typ.
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