Click Dehydrogenation of Carbon-Substituted nido-5,6-C2B8H12 Carboranes: A General Route to closo-1,2-C2B8H10 Derivatives

0463696 - ÚACH 2017 RIV US eng J - Článek v odborném periodiku
Tok, Oleg L. - Bakardjiev, Mario - Štíbr, Bohumil - Hnyk, Drahomír - Holub, Josef - Padělková, Z. - Růžička, A.
Click Dehydrogenation of Carbon-Substituted nido-5,6-C2B8H12 Carboranes: A General Route to closo-1,2-C2B8H10 Derivatives.
Inorganic Chemistry. Roč. 55, č. 17 (2016), s. 8839-8843. ISSN 0020-1669. E-ISSN 1520-510X
Grant CEP: GA ČR(CZ) GA16-01618S
Institucionální podpora: RVO:61388980
Klíčová slova: magnetic-resonance-spectroscopy * structural-characterization * monocarbaborane chemistry
Kód oboru RIV: CA - Anorganická chemie
Impakt faktor: 4.857, rok: 2016

Triethylamine-catalyzed dehydrogenation of carbon-disubstituted dicarbaboranes 5,6-R-2-nido-5,6-C2B8H10 [1, where R = H (1a), Me (1b), and Ph (1c)] in refluxing acetonitrile leads to a high-yield (up to 85-95%) formation of a series of dicarbaboranes 1,2-R-2-closo-1,2-C2B8H8 (2). The monosubstituted 6-R-nido-5,6-C2B8H11 (3) analogues [where R = Ph (3a), naph (1-naphthyl; 3b), Bu (3c)] afforded 1-R-1,2-closo C2B8H9 (4) isomers [where R = Ph (4a), naph (4b), n-Bu (4c)] as the main products; compounds 4a and 4c were accompanied by 2-R-1;2-C2B8H9 (5) isomers (total yields up to 90%), with the 4/5 molar ratio being strongly dependent on the nature of R (4:1 and 1:1, respectively). All of these cage-closure reactions are supposed to proceed via the stage of the corresponding Et3NH+ salts of nido anions [5,6-R-2-5,6-C2B8H9](-) (1(-)) and [6-R-5,6-C2B8H10](-) (3(-)), which lose H-2 and Et3N upon heating (dehydrodeamination). The cage-closure mechanisms leading to closo isomers 2, 4, and 5 have been substantiated by B3LYP/6-31+G* calculations of the reaction profile for a simple 1a(-) -> 2a + H- conversion. All of the compounds isolated have been characterized by multinuclear (B-11, H-1, and C-13) NMR spectroscopy, mass spectrometry, and elemental analyses, and the structure of 1-Ph-closo-1,2-C2B8H9 (4a) was established by an X-ray diffraction study.
Trvalý link: http://hdl.handle.net/11104/0263472


Vědecká data: ACS publications