| Autor: |
Golub IE; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia., Filippov OA; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia., Belkova NV; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia., Epstein LM; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia., Shubina ES; A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia. |
| Abstrakt: |
The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH 4 ] - by hydrogen halides (HX, X = F, Cl, Br) and hexahydro- closo -hexaborate dianion [B 6 H 6 ] 2- by HCl via electrophile-induced nucleophilic substitution (EINS) was established by ab initio DFT calculations [M06/6-311++G(d,p) and wB97XD/6-311++G(d,p)] in acetonitrile (MeCN), taking into account non-specific solvent effects (SMD model). Successive substitution of H - by X - resulted in increased electron deficiency of borohydrides and changes in the character of boron atoms from nucleophilic to highly electrophilic. This, in turn, increased the tendency of the B-H bond to transfer a proton rather than a hydride ion. Thus, the regularities established suggested that it should be possible to carry out halogenation more selectively with the targeted synthesis of halogen derivatives with a low degree of substitution, by stabilization of H 2 complex, or by carrying out a nucleophilic substitution of B-H bonds activated by interaction with Lewis acids (BL 3 ). |
