Anion packing, hole filling, and HF solvation in A(2)(HF)(n)B12F12 and K-2(HF)TiF6 (A = K, Cs)

作者：Peryshkov Dmitry V; Friedemann Roland; Goreshnik Evgeny; Mazej Zoran^*; Seppelt Konrad; Strauss Steven H

来源：Journal of Fluorine Chemistry, 2013, 145: 118-127.

DOI：10.1016/j.jfluchem.2012.10.009

• Fluoroanion
• Hydrogen fluoride complex
• Potassium
• Polyhedral borane

The crystal structures of three new HF solvates of fluoroanion salts of alkali metal ions are reported, K-2(HF)TiF6, K-2(HF)(3)B12F12, and Cs-2(HF)B12F12. The anion packing in K-2(HF)TiF6 (P2(1)/m) is distorted cubic close-packed with Ti center dot center dot center dot Ti distances that range from 5.717(1) to 7.394(1) angstrom (average 6.18 angstrom). Half of the K ions are in T-d holes and half are in O-h holes (i.e., this is a distorted version of the C5S structure). Each HF molecule is bonded to a K ion in the O-h holes (K-F(H) = 2.679(5) angstrom) and also weakly interacts with two other K ions in adjacent O-h holes (K center dot center dot center dot F(H) = 3.238(2) angstrom). The anion packing in K-2(HF)(3)B12F12 (Fm (3) over barm) is simple cubic. The (B-12 centroid)center dot center dot center dot(B-12 centroid) distance (circle dot center dot center dot center dot circle dot distance) is 7.242 angstrom, and disordered K-2(mu-HF)(3)(2 ) cations occupy each cube. The anion packing in Cs-2(HF)B12F12 (P2(1)/c) is distorted hexagonal close-packed with circle dot center dot center dot center dot circle dot distances that range from 7.217 to 9.408 angstrom (average 8.304 angstrom). The HF molecule bridges Cs ions in adjacent O-h holes, forming infinite Cs -(mu-HF)-Cs -(mu-HF)- chains. The other half of the Cs ions are in T-d holes, displaced nearly 1 angstrom from the center of those holes. This structure is similar to the distorted Ni2In structure exhibited by Cs-2(H2O)B12F12. The new results are used to compare and contrast the strength of M-F(H) interactions with M-F interactions involving F atoms from fluoroanions as well as the solid-state packing of icosahedral B12F122- anions and octahedral MF62- anions in alkali-metal salts, both with and without the inclusion of weakly-basic HF solvent molecules.

• 出版日期2013-1