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  • CaSi  (1)
  • Crystal Structures  (1)
  • LiMg[BN2]  (1)
  • 1
    Electronic Resource
    Electronic Resource
    Weinheim : Wiley-Blackwell
    Zeitschrift für anorganische Chemie 622 (1996), S. 85-94 
    ISSN: 0044-2313
    Keywords: Alkaline Earth Silicides ; Zintl Anions of Silicon ; SrMgSi2 ; Mg2Sr11Si10 ; CaSi ; BaSi ; SrSi ; Crystal Structures ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Can One Design Zintl Anions? Contributions from the System Sr/Mg/Si to the Topic Si2-Two novel ternary silicides, SrMgSi2 (Pnma, Z = 8, a = 14.374, b = 4.4512, c = 11.398 Å) and Sr11Mg2Si10, (C2/m, Z = 2, a = 19.744, b = 4.754, c = 14.84 Å, β = 112.47°) have been established in the ternary system Sr/Mg/Si. The compounds are synthezised from the elements under inert conditions. Single crystal structure determinations yield the novel Zintl anions, ∞1[Si(Si3)8-] a branched chain, and the zig-zag chain piece [Si8]18-, both of which exhibit significant correlations and differences with respect to the linear chains in ∞1[Si-] in the binary MSi phases (M = Ca, Sr, Ba) which have been reinvestigated in this context. The variations of the Zintl anions can be traced back mainly to the differences of Mg—Si and Sr—Si interactions. From these findings a functional relationship between Mg content and the formation of endgroup members in Zintl anions of silicon is anticipated.
    Notes: Es wird über Darstellung und Strukturen neuer ternärer Silicide aus dem System Sr/Mg/Si berichtet. Zwei neue Verbindungen SrMgSi2 (Pnma, Z = 8, a = 14,374, b = 4,4512, c = 11,394 Å) und Sr11Mg2Si10 (C2/m, Z = 2, a = 19,744, b = 4,754, c = 14,84 Å, β = 112,47°) wurden aus den Elementen unter Inertbedingungen synthetisiert. Sie können als Abkömmlinge der binären Monosilicide MSi (M = Ca, Sr, Ba) verstanden werden, die in diesem Zusammenhang noch einmal genau untersucht wurden. Ihre Kristallstrukturen enthalten die neuartigen Zintlanionen ∞1[Si(Si3)8-], eine verzweigte Kette, und [Si818-] mit signifikanten Unterschieden zur linearen Kette ∞1[Si-] in den MSi-Phasen. Die Variationen der Zintlanionen können vor allem auf die unterschiedlichen Wechselwirkungen Mg—Si und Sr—Si zurückgeführt und damit ein funktioneller Zusammenhang zwischen dem Mg-Gehalt und der Endgruppenbildung in Zintlanionen von Si hergestellt werden.
    Additional Material: 6 Ill.
    Type of Medium: Electronic Resource
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  • 2
    ISSN: 0044-2313
    Keywords: LiMg[BN2] ; Ba4[BN2]2O ; Nitridoborates ; Linear Anions [BN2]3- ; Crystal Structure ; Vibrational Spectrum ; Chemistry ; Inorganic Chemistry
    Source: Wiley InterScience Backfile Collection 1832-2000
    Topics: Chemistry and Pharmacology
    Description / Table of Contents: Ternary Nitridoborates. 1. LiMg[BN2] and Ba4[BN2]2O, Compounds with the Anion [N—B—N]3-: Syntheses, Crystal Structures, and Vibrational SpectraLiMg[BN2] and Ba4[BN2]2O were synthesized from stoichiometric mixtures of the binary components Li3N, Mg3N2, BN and BaO, Ba3N2. BN in sealed niobium ampoules at 1575 and 1350 K, respectively. The structures are characterized by isolated anions [N—B—N]3-, packed in different ways (LiMg[BN2]: I4/mmm (No. 139); a = 379.8 pm, c = 891.6 pm, c/a = 2.348; Z = 2; Ba4[BN2]2O; Cmca (No. 64); a = 1575.3 pm, b = 729.1 pm, c = 731.9 pm; Z = 4). The bond lengths and the bond angles are d(B—N) = 133.6 pm and β(N—B—N) = 180° in LiMg[BN2] and d(B—N) = 135 pm and β(N—B—N) = 173.4° in Ba4[BN2]2O, respectively.The vibrational spectra have been interpreted with respect to the D∞h symmetry of the isolated [N—B—N]3- anions, taking into account the slight symmetry reduction to C2v in Ba4[BN2]2O. The calculated valence force constants f(B—N) = 8.16 Ncm-1 and f(B—N) = 7.55 Ncm-1 are discussed and compared with those of other nitridoborates.
    Notes: LiMg[BN2] und Ba4[BN2]2O bilden sich aus stöchiometrischen Gemengen der binären Komponenten Li3N, Mg3N2, BN bzw. BaO, Ba3N2, BN in verschweißten Nb-Ampullen bei 1575 bzw. 1350 K. Die charakteristischen Bauelemente sind isolierte [N—B—N]3- -Anionen, die im Kristall unterschiedlich gepackt sind (LiMg[BN2]: I4/mmm (Nr. 139); a = 379.8 pm, c = 891.6pm, c/a = 2.348; Z = 2; Ba4[BN2]2O: Cmca (Nr.64); a = 1575.3 pm, b = 729.1pm, c = 731.9 pm; Z = 4). Die Bindungslängen und Bindungswinkel betragen d(B—N) = 133.6 pm und β(N—B—N) = 180° in LiMg[BN2] bzw. d(B—N) = 135 pm und β(N-B-N) = 173.4° in Ba4[BN2]2O.Die Schwingungsspektren der Verbindungen wurden auf der Basis der D∞h-Symmetrie der isolierten [N—B—N]3--Anionen unter Berücksichtigung der Symmetrieerniedrigung nach C2v in Ba4[BN2]2O interpretiert. Die aus den gemessenen Frequenzen berechneten Kraftkonstanten f(B—N) = 8.16 bzw. 7.55 Ncm-1 werden diskutiert und mit denen anderer Nitridoborate verglichen.
    Additional Material: 3 Ill.
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