Darstellung,¹¹B-NMR- und Schwingungsspektren isomerenreiner Halogenohydrodecaborate X_nB₁₀H_{10- n} ^2-; X = Cl, Br, I; n = 1, 2 / Preparation, ¹¹B NMR and Vibrational Spectra of Pure Isomeric Halohydrodecaborates X_nB₁₀H_{10- n} ^2-; X = Cl, Br, I; n = 1, 2

Abstract

<jats:p>Pure isomers of X<jats:sub>n</jats:sub>B<jats:sub>10</jats:sub>H<jats:sub>10-n</jats:sub><jats:sup>2-</jats:sup>; X = Cl, Br, I; n = 1, 2; are isolated by ion exchange chromatography on diethylaminoethylcellulose. Their structures are determined by<jats:sup>11</jats:sup>B and <jats:sup>11</jats:sup>B {<jats:sup>1</jats:sup>H }NMR spectroscopy. There are characteristic chemical shifts due to apical and equatorial substituents, respectively. The highest field signals are explained by the antipodal effect. In contrast to theoretical predictions the experimental investigations show, that the successive electrophilic substitution preferably occurs on equatorial and not on apical B atoms. IR and Ram an spectra of the 2-XB<jats:sub>10</jats:sub>H<jats:sub>9</jats:sub><jats:sup>2-</jats:sup>species are very similar in the ν(BH) and in the B<jats:sup>10- </jats:sup>cage absorption region. In the far infrared there are two characteristic bands, shifting to lower frequencies in the series Cl, Br, I, which are therefore assigned to (B<jats:sub>10</jats:sub>) - X stretching and (B<jats:sub>10</jats:sub>) - X deformation modes.</jats:p>