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Unexpected Formation of the Highly Symmetric Borate Ion [B(SiCl 3 ) 4 ] −
Author(s) -
Bochmann Sebastian,
Böhme Uwe,
Brendler Erica,
Friebel Mike,
Gerwig Maik,
Gründler Franziska,
Günther Betty,
Kroke Edwin,
Lehnert Robert,
Ruppel Lars
Publication year - 2021
Publication title -
european journal of inorganic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.667
H-Index - 136
eISSN - 1099-0682
pISSN - 1434-1948
DOI - 10.1002/ejic.202100246
Subject(s) - chemistry , boron , protonation , boron trichloride , toluene , crystallography , raman spectroscopy , nuclear magnetic resonance spectroscopy , crystal structure , nmr spectra database , ion , polyatomic ion , inorganic chemistry , medicinal chemistry , stereochemistry , organic chemistry , spectral line , physics , astronomy , optics
Disproportionation reactions of chlorosilane compounds in the presence of boron trichloride yield the compound H[B(SiCl 3 ) 4 ]. Spectroscopic analyses of the yellow‐whitish solid with IR‐, Raman‐, and NMR‐spectroscopy ( 29 Si, 11 B) show the presence of a highly symmetric anion containing boron, which is fourfold coordinated with silicon. Due to the high symmetry 1 J( 11 B, 29 Si) and even 1 J ( 10 B, 29 Si) couplings can be observed in the NMR spectra of the dissolved compound. The crystal structure analysis with a crystal obtained from toluene solution proves the existence of a highly symmetric borate anion, which is stabilized by four trichlorosilyl groups. The molecular structure consists of a para‐protonated toluene cation and the weakly coordinating borate anion [B(SiCl 3 ) 4 ] − . Quantum chemical analysis of the tetrakis(trichlorosilyl)borate ion shows a negatively charged boron atom and the presence of polar Si−Cl and Si−B bonds. Highly reactive compounds [E(SiCl 3 ) n ] − which are stabilized solely by trichlorosilyl groups have been prepared with E=C, Si, Ge, P, S in recent years. The superacid H[B(SiCl 3 ) 4 ] represents a new member in this elusive compound family.