Darstellung, ¹¹B-NMR- und Schwingungsspektren isomerenreiner Halogenohydrododecaborate X_nB₁₂H_12–n ^2–; X = Cl, n = 1–3; X = Br, n = 1,2; X = I, n = 1 / Preparation, nB NMR and Vibrational Spectra of Pure Isomeric Halohydrododecaborates X_nB₁₂H_12-n ^2-; X = Cl, n = 1-3; X = Br, n = 1,2; X = I, n = 1

Abstract

<jats:p>Pure isomers of X<jats:sub>n</jats:sub>B<jats:sub>12</jats:sub>H<jats:sub>12-n</jats:sub><jats:sup>2-</jats:sup>; X = Cl, Br, I are isolated by ion exchange chromatography on diethylaminoethyl cellulose. The 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. With X = Cl, Br the signal of ipso-B atomes is shifted to lower, with X = I to higher field compared with B<jats:sub>12</jats:sub>H<jats:sub>12</jats:sub><jats:sup>2-</jats:sup>. The resonances of B-atoms influenced by the antipodal effect are observed at high field, increasing within the series I&lt;Br&lt;Cl. The chemical shifts are explained by the anisotropy effect and by the paramagnetic term due to different -I and +M effects of the halogens. In agreement with theoretical predictions the substitution of B<jats:sub>12</jats:sub>H<jats:sub>12</jats:sub><jats:sup>2-</jats:sup> with chlorine proceeds successively at vicinal positions B(1) -B(2) -B(3). The IR and Raman spectra of 1-XB<jats:sub>12</jats:sub>H<jats:sub>11</jats:sub><jats:sup>2-</jats:sup> show in the region 175 - 380 cm <jats:sup>-1</jats:sup> two characteristic bands shifting to lower frequencies in the series Cl, Br, I and are therefore assigned to (B<jats:sub>12</jats:sub>) -X stretching and (B<jats:sub>12</jats:sub>) -X bending modes, respectively</jats:p>

GIAO versus GIPAW: Comparison of Methods To Calculate 11B NMR Shifts of Icosahedral Closo-Heteroboranes toward Boron-Rich Borides

“…Applying GIPAW, Mauri et al related the calculated shieldings (PW91, 50 Ry) 36 to experimental shifts for (B 12 H 12 ) 2− (−14.9 ppm). 71 Because they are conservatively referenced to (B 12 H 12 ) 2− , it is possible to relate their obtained values to our reference (−15.3 ppm) and to apply a shift of −0.4 ppm to their value, thus showing a perfect agreement, within 0.1 ppm, to our results of δ ref GIPAW in Table 4. An extensive study on the 11 B NMR shifts on the optimized structure (RMP2(fc)/6-31G*) of compound (6) regarding basis sets using GIAO is reported in ref 43.…”

Reduction of Triple Bond in [B12H11NCR]− Anions by Lithium Aluminum Hydride: A Novel Approach to the Synthesis of N-Monoalkylammonio-Substituted closo-Dodecaborates

“…Such processes include reactions of exhaustive halogenation of the free anion [B 12 H 12 ] 2− and its substituted derivatives [30][31][32][33], as well as the formation of closomer anions [B 12 (OH) 12 ] 2− and [B 12 (OH) 11 NH 3 ] − [34,35]. Electrophilic processes are used to obtain carbonyl derivatives [36], halogen-closo-dodecaborates with low degrees of substitution [37] and alkyl and aryl derivatives [38]. The reaction of [B 12 H 12 ] 2− anion with hydroxylamine-O-sulfonic acid proceeds through an electrophilic mechanism [39].…”