Related Experiment Video
Updated: Aug 6, 2026

Preparation and Reactivity of a Triphosphenium Bromide Salt: A Convenient and Stable Source of Phosphorus(I)
Published on: November 22, 2016
Cesium hydridotris(trifluoromethyl)borate, Cs[(CF3)3BH]
Jens Geier1, Gottfried Pawelke, Helge Willner
1Bergische Universität Wuppertal, FB C - Anorganische Chemie, Gaussstrasse 20, D-42097 Wuppertal, Germany. geier@uni-wuppertal.de
Abstract:
Treatment of Cs[(CF3)3BNH2] with the aminating agent H2NOSO3H in aqueous solution allowed the isolation of pure Cs[(CF3)3BH], which is stable up to 300 degrees C. Due to the strong electron-withdrawing effect of the CF3 substituents, the [(CF3)3BH]- anion behaves as a very unreactive hydride. It is stable in concentrated hydrochloric acid for many days but reacts cleanly with F2, Cl2, and Br2 to the corresponding haloborates. The molecular structure was determined by single-crystal X-ray diffraction. Crystal data: orthorhombic, space group Pnma; a = 11.4296(5) A, b = 7.9510(4) A, c = 9.7268(5) A; V = 883.94(7) A(3), Z = 4; R1 = 0.0294, wR2 = 0.0818. The anions exhibit only Cs symmetry in the lattice. The natural and deuterated anions were characterized by IR, Raman, and multinuclear NMR spectroscopy; vibrational assignments were supported by DFT calculations. QTAIM charges derived from the B3LYP electron density are given for [(CF3)3BH]- and several related anions.
Related Concept Videos
Hybridization of Atomic Orbitals I
Exceptions to the Octet Rule
Hybridization of Atomic Orbitals II
VSEPR Theory and the Basic Shapes
Hydroboration-Oxidation of Alkenes
Radicals: Electronic Structure and Geometry
Accordingly, the structure of a trivalent radical lies between the geometries of carbocations and carbanions. An sp2-hybridized carbocation is trigonal planar, while an sp3-hybridized carbanion is trigonal pyramidal. Here, the difference in geometry is...

