The Reaction of Hydrogen Halides with Tetrahydroborate Anion and Hexahydro-closo-hexaborate Dianion

Molecules

Lina M. Epstein¹  Igor E. Golub¹  Elena S. Shubina¹  Oleg A. Filippov¹  Natalia V. Belkova¹ 

[1] A. N. Nesmeyanov Institute of Organoelement Compounds, Russian Academy of Sciences (INEOS RAS), 28, Vavilova St, 119991 Moscow, Russia;

关键词: borohydride;    polyhedral closo-borane;    proton transfer;    Lewis acidity;    hydride donor ability;    DFT calculations;   

DOI  :  10.3390/molecules26123754

来源: DOAJ

【 摘 要 】

The mechanism of the consecutive halogenation of the tetrahydroborate anion [BH₄]⁻ by hydrogen halides (HX, X = F, Cl, Br) and hexahydro-closo-hexaborate dianion [B₆H₆]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 H₂ complex, or by carrying out a nucleophilic substitution of B–H bonds activated by interaction with Lewis acids (BL₃).

【 授权许可】

Unknown