Cesium hydridotris(trifluoromethyl)borate, Cs[(CF3)3BH]

Treatment of Cs[(CF3)(3)BNH2] with the aminating agent H2NOSO3H in aqueous solution allowed the isolation of pure Cs[(CF3)(3)BH], which is stable up to 300 degrees C. Due to the strong electron-withdrawing effect of the CF3 substituents, the [(CF3)(3)BH](-) anion behaves as a very unreactive hydride. It is stable in concentrated hydrochloric acid for many days but reacts cleanly with F-2, Cl-2, and Br-2 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) angstrom, b = 7.9510(4) angstrom, c = 9.7268(5) angstrom; V = 883.94(7) angstrom(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)(3)BH](-) and several related anions.