New Ways to a Series of Parent Representatives of the Eight‐, Nine‐, and Ten‐Vertex Monocarbaborane Family

Autor: Drahomír Hnyk, Mathias Hofmann, Bernd Brellochs, Tomáš Jelínek, Jaroslav Bačkovský, Berndt Wrackmeyer, Ivana Cisarova, Mario Bakardjiev, Josef Holub, Bohumil Štíbr
Rok vydání: 2004
Předmět:
Zdroj: European Journal of Inorganic Chemistry. 2004:3605-3611
ISSN: 1099-0682
1434-1948
DOI: 10.1002/ejic.200400125
Popis: The conditions for a reaction between nido-B10H14 (1) and aqueous formaldehyde in an alkaline solution have been optimized, which resulted in the isolation of the [arachno-6-CB9H14]− anion (2) in 52% yield. Anion 2 was used as a convenient source for the synthesis of a series of basic monocarbaborane compounds. Thus, oxidation of 2 (Et4N+ salt) with I2 in CH2Cl2 in the presence of Et3N at room temperature afforded the [nido-6-CB9H12]− anion (3). Acidification of anion 2 (generated in situ from borane 1) with hydrochloric acid, in the presence of both FeCl3·6H2O and CH2O, led to the formation of arachno-4-CB8H14 (4), from which nido-1-CB8H12 (5) was obtained by dehydrogenation at 200 °C in quantitative yield. Compound 4 can easily be converted into the [closo-1-CB7H8]− anion (6) in 71% yield via reaction with Et3N and I2 in THF at −78 °C. Anion 6 is also formed in 75% yield by treatment of carborane 5 with Et3N in refluxing toluene. The [closo-1-CB8H9]− anion (7) was isolated by iodination of carborane 5 in the presence of Et3N (yield 81%) or by the heating of the PPh4+ salt of anion 2 at 220 °C (yield 95%). The structure of anion 2 was determined by an X-ray diffraction study and the structures of compounds 2, 4, 5, and 7 were geometry optimized at the RMP2(fc)/6-31G* level. The NMR spectroscopic measurements are in some cases complemented by unpublished 13C NMR spectroscopic data. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)
Databáze: OpenAIRE
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