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.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/zaac.19976230104
