New ways to a series of parent representatives of the eight-, nine-, and ten-vertex monocarbaborane family

0106540 - UACH-T 20043026 RIV DE eng J - Journal Article
Brellochs, B. - Bačkovský, Jaroslav - Štíbr, Bohumil - Jelínek, Tomáš - Holub, Josef - Bakardjiev, Mario - Hnyk, Drahomír - Hofmann, M. - Cásařová, I. - Wrackmeyer, B.
New ways to a series of parent representatives of the eight-, nine-, and ten-vertex monocarbaborane family.
[Nové cesty k serii mateřských representantů 8-, 9- a 10-vrcholové rodiny monokarbaboranů.]
European Journal of Inorganic Chemistry. -, č. 18 (2004), s. 3605-3611. ISSN 1434-1948. E-ISSN 1099-0682
R&D Projects: GA AV ČR IBS4032007; GA MŠMT LN00A028
Institutional research plan: CEZ:AV0Z4032918
Keywords : boranes * carboranes * geometry optimization
Subject RIV: CA - Inorganic Chemistry
Impact factor: 2.336, year: 2004

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 I-2 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 FeCl3-6H(2)O and CH2O, led to the formation of arachno-4-CB8H4 (4), from which nido-1-CB8H12 (5) was obtained by dehydrogenation at 200 degreesC in quantitative yield. Compound 4 can easily be converted into the [closo-1-CB7H8](-) anion (6) in 71% yield via reaction with Et3N and I-2 in THF at -78 degreesC. 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 degreesC (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 The NMR spectroscopic measurements are in some cases complemented by unpublished C-13 NMR spectroscopic data.

Je popsána příprava nových představitelů 8-, 9- a 10-vrcholové serie monokarbaboranů, která je založena na postupné degradaci dekaboranového skeletu za různých reakčních podmínek.
Permanent Link: http://hdl.handle.net/11104/0013718