Unexpected Formation of the Highly Symmetric Borate Ion [B(SiCl ₃ ) ₄ ] ⁻

Disproportionation reactions of chlorosilane compounds in the presence boron trichloride yield compound H[B(SiCl3)4]. Spectroscopic analyses yellow-whitish solid with IR-, Raman-, and NMR-spectroscopy (29Si, 11B) show a highly symmetric anion containing boron, which is fourfold coordinated silicon. Due to high symmetry 1J(11B,29Si) even 1J (10B, 29Si) couplings can be observed NMR spectra dissolved compound. The crystal structure analysis obtained from toluene solution proves existence borate anion, stabilized by four trichlorosilyl groups. molecular consists para-protonated cation weakly coordinating [B(SiCl3)4]−. Quantum chemical tetrakis(trichlorosilyl)borate ion shows negatively charged atom polar Si−Cl Si−B bonds. Highly reactive [E(SiCl3)n]− are solely groups have been prepared E=C, Si, Ge, P, S recent years. superacid H[B(SiCl3)4] represents new member this elusive family.