Darstellung und 11B-NMR-Spektren perhalogenierter closo-Hexaborate Β6ΧnY6-n 2-, n=0-6; X ≠ Y= Cl, Br, I / Preparation and 11B NMR Spectra of the Perhalogenated closo-Hexaborates B6XnY6-n 2-,n = 0-6; Χ ≠ Υ = Cl, Br, I
Open Access
- 1 August 1990
- journal article
- Published by Walter de Gruyter GmbH in Zeitschrift für Naturforschung B
- Vol. 45 (8) , 1113-1117
- https://doi.org/10.1515/znb-1990-0801
Abstract
The mixed halogenohexaborates B6XnY6-n 2-, n = 1-5; Χ ≠ Υ = Cl, Br, I, including most of the pure stereoisomers for n = 2—4, are prepared for the first time by treatment of the halohydrohexaborates B6XnH6-n 2-, X = Cl, Br in aqueous alkaline solution with bromine and iodine or with halogenosuccinimides. The point symmetry is determined from the "B NMR spectra, which show characteristic features for homologous isostructural compounds. In the systems B6XnY6-n 2- a considerable dispersion of the 11B signals is observed, for B(X) atoms to lower, for B(Y) atoms to higher field compared with B6X6 2- and B6Y6 2- (electronegativity X > Y), respectively. An additional chemical shift is caused by the mutual antipodal effect between pairs of opposite B atoms carrying different substituents. From the systematic influences on the chemical shifts the 11B NMR spectra of the missing species fac-B6X3Y3 2- are calculated.Keywords
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