Random disordering in hydroxo derivatives of closo-[B12H12](2-) anion: Crystal structures of Cs-2[B12H11(OH)] center dot CH3C(O)OH and (PPh4)(2)[B12H11(OH)] center dot xCH(3)C(O)OH center dot yH(2)O

The structures of two compounds containing a monosubstituted borohydride an ion, CS2[B12H11 (OH)] . CH3C(O)OH (I) and (PPh4)(2)[B12H11(OH)] . xCH(3)C(O )OH . yH(2)O (II), were determined by X-ray crystallography. Crystals of I are tetragonal: a = 7.891(2) Angstrom, c = 24.557(5) Angstrom, V = 1529.0(7 ) Angstrom (3), Z = 4, space group P4(2)/nnm. Crystals of II are triclinic: a = 11.043(3) Angstrom, b = 11.143(4) Angstrom, c = 11.445(3) Angstrom, al pha = 75.15(3)degrees, beta = 71.43(3)degrees, gamma = 80.07(3)degrees, V = 1284.1(8) Angstrom (3), Z = 1, space group P (1) over bar. Crystals of bot h I and II are composed of corresponding cations, [B12H11(OH)](2-) anions, and solvation CH3C(O)OH molecules. The B-O bond lengths in I and II are wit hin 1.40-1.44 Angstrom; the B-B bonds fall within 1.76-1.80 Angstrom. The h ydroxy substituent in the anion is disordered over several positions. The s tructures were solved by the heavy-atom method and refined anisotropically (isotropically for H atoms) by full-matrix least squares calculation; R = 0 .0302, wR2 = 0.099, and GOOF = 1.02 for I and R =0.0410, wR2 = 0.1486, and GOOF = 1.01 for II.