| | 1 | Author
| A. Heinrich, W. Preetz | Requires cookie* | | | Title
| Darstellung und Schwingungsspektren von Alkyl-und Rhodanohydrohexaboraten Preparation and Vibrational Spectra of Alkyl and Rhodano Hydrohexaborates  | | | | Abstract
| Treatment of B 6 H 6 2 " with iodoalkanes and (SCN) 2 in organic solvents affords the monosubsti-tuted protonated hexaborates RB 6 H 6 ", R = CH 3 , C 2 H 5 < C 3 H 7 , C 4 H 9 , C 8 H 17 and SCN, respective-ly. The acidity constants of these weak Brönsted acids range for the alkylated species from 8.8 to 9.6, and for R = SCN the pk a value is ~5. From basic solutions the salts Cs 2 RB 6 H 5 can be precipitated, which show band patterns in the IR and Raman spectra typical for monosubstituted hydrohexaborates. The protonated compounds RB 6 H 6 " are distinguished from the corresponding Brönsted bases RB 6 H 5 2 " by a high frequency shift of the BH stretching vibrations in the order of 100 cm" 1 . For Cs 2 (SCN)B 6 H 5 , S coordination of SCN" is supposed because of the high frequency of v CN : 2144 cm" 1 . | | | |
Reference
| Z. Naturforsch. 43b, 1327—1331 (1988); eingegangen am 8. Juli 1988 | | | |
Published
| 1988 | | | |
Keywords
| Alkylhydrohexaborates, Rhodanohydrohexaborate, Protonation, IR Spectra, Raman Spectra | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1327.pdf | | | | Identifier
| ZNB-1988-43b-1327 | | | | Volume
| 43 | |
| 2 | Author
| A. Heinrich, W. Preetz, H. C. Marsmann | Requires cookie* | | | Title
| n B-NMR-Spektren von Alkyl-, Halogeno-und Rhodanohydrohexaboraten "B NMR Spectra of Alkyl-, Halogeno-and Rhodanohydrohexaborates | | | | Abstract
| The temperature dependence of the "B NMR spectra of the monosubstituted and protonated c/oso-hexaborates RB 6 H 6 ", R -CH 3 , C : H 5 , C,H 7 , QH,,, C 8 H 17 , (SCN)B h H 6 -. and XB h H h . X = Cl. Br. I, has been determined in the range 180—300 K. The extra proton migrates at higher temperatures intramolecularly, probably across the edges of the B fl core. The extra proton is fixed to a facet of the octahedron below the coalescence temperatures 240 K (RB h H 6 ~) and 210 K (XB(,H 6 ") as recognized by the splitting of the signal of the equatorial B atoms due to the lowering of the symmetry from C 4v to C s . From the spin-spin coupling it can be deduced that the proton prefers with the softer Brönsted acids RB 6 H 6 " facets adjacent to the substituent, while with the stronger Brönsted acids XB h H 6 facets including the antipodal B atom are occupied. | | | |
Reference
| Z. Naturforsch. 43b, 1647—1652 (1988); eingegangen am 23. August 1988 | | | |
Published
| 1988 | | | |
Keywords
| Alkylhydrohexaborates, Halogenohydrohexaborates, Rhodanohydrohexaborate, "B and "B{'H} NMR Spectra | | | |
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| default:Reihe_B/43/ZNB-1988-43b-1647.pdf | | | | Identifier
| ZNB-1988-43b-1647 | | | | Volume
| 43 | |
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