Electrophilic Methylation of Decaborane(14): Selective Synthesis of Tetramethylated and Heptamethylated Decaboranes and Their Conjugated Bases

0531876 - ÚACH 2021 RIV US eng J - Journal Article
Holub, Josef - Růžička, A. - Růžičková, Z. - Fanfrlík, Jindřich - Hnyk, Drahomír - Štíbr, Bohumil
Electrophilic Methylation of Decaborane(14): Selective Synthesis of Tetramethylated and Heptamethylated Decaboranes and Their Conjugated Bases.
Inorganic Chemistry. Roč. 59, č. 15 (2020), s. 10540-10547. ISSN 0020-1669. E-ISSN 1520-510X
R&D Projects: GA ČR(CZ) GA19-17156S
Institutional support: RVO:61388980 ; RVO:61388963
Keywords : carboranes * nuclear magnetic resonance spectroscopy * molecular structure * mixtures * reaction products
OECD category: Inorganic and nuclear chemistry; Physical chemistry (UOCHB-X)
Impact factor: 5.165, year: 2020
Method of publishing: Limited access
https://pubs.acs.org/doi/10.1021/acs.inorgchem.0c00917

The paper reports specific syntheses of methylated decaborane(14), nido-B10H14 (1), derivatives. The reaction of 1 with an excess of neat MeI and AlCl3 yields 1,2,3,4-Me-4-nido-B10H10 (2) essentially quantitatively when performed at room temperature. Heating the same mixture to 120 degrees C provides 1-I-2,3,4,5,7,8,10-Me-7-nido-B10H6 (3a). The formation of analogous 1-CF3SO2O-2,3,4,5,7,8,10-Me-7-nido-B10H6 (3b) is achieved by heating 1 or 2 with an excess of MeSO3CF3 in the presence of a catalytic amount of HOSO2CF3 to 120 degrees C. Compounds 2 and 3 can be deprotonated to yield the corresponding anions [1,2,3,4-Me-4-nido-B10H9](-) (2(-)), [1-I-2,3,4,5,7,8,10-Me-7-nido-B10H5](-) (3a(-)), and [1-CF3SO2O-2,3,4,5,7,8,10-Me-7-nido-B10H5](3b(-)). The structure of all the compounds isolated has been unambiguously confirmed by multinuclear (B-11 and H-1) NMR measurements, and the structures of 2(-), 3a, 3a(-), and 3b have been established by X-ray diffraction analyses. The very high volatility of 2 has made it impossible to apply X-ray diffraction in this case, therefore, its structure has been derived computationally using the ab initio/GIAO/NMR tool. DFT-based computational protocols have also outlined the reason why it is impossible to obtain an octamethyl derivative of 1 experimentally.
Permanent Link: http://hdl.handle.net/11104/0310516


Research data: CCDC, ACS publications