# Structures of M_{2}(SO_{2})_{6}B_{12}F_{12} (M = Ag or K) and Ag_{2}(H_{2}O)_{4}B_{12}F_{12}: Comparison of
the Coordination of SO_{2} versus H_{2}O and of B_{12}F_{12}^{2–} versus Other Weakly Coordinating
Anions to Metal Ions in the Solid State

journal contribution

posted on 2016-11-14, 16:19 authored by Moritz Malischewski, Dmitry V. Peryshkov, Eric V. Bukovsky, Konrad Seppelt, Steven H. StraussThe structures of
three solvated monovalent cation salts of the superweak anion B

_{12}F_{12}^{2–}(Y^{2–}), K_{2}(SO_{2})_{6}Y, Ag_{2}(SO_{2})_{6}Y, and Ag_{2}(H_{2}O)_{4}Y, are reported and discussed with respect to previously reported structures of Ag^{+}and K^{+}with other weakly coordinating anions. The structures of K_{2}(SO_{2})_{6}Y and Ag_{2}(SO_{2})_{6}Y are isomorphous and are based on expanded cubic close-packed arrays of Y^{2–}anions with M(OSO)_{6}^{+}complexes centered in the trigonal holes of one expanded close-packed layer of B_{12}centroids (⊙). The K^{+}and Ag^{+}ions have virtually identical bicapped trigonal prism MO_{6}F_{2}coordination spheres, with M–O distances of 2.735(1)–3.032(2) Å for the potassium salt and 2.526(5)–2.790(5) Å for the silver salt. Each M(OSO)_{6}^{+}complex is connected to three other cationic complexes through their six μ-SO_{2}-κ^{1}*O*,κ^{2}*O*′ ligands. The structure of Ag_{2}(H_{2}O)_{4}Y is unique [different from that of K_{2}(H_{2}O)_{4}Y]. Planes of close-packed arrays of anions are offset from neighboring planes along only one of the linear ⊙···⊙···⊙ directions of the close-packed arrays, with [Ag(μ-H_{2}O)_{2}Ag(μ-H_{2}O)_{2})]_{∞}infinite chains between the planes of anions. There are two nearly identical AgO_{4}F_{2}coordination spheres, with Ag–O distances of 2.371(5)–2.524(5) Å and Ag–F distances of 2.734(4)–2.751(4) Å. This is only the second structurally characterized compound with four H_{2}O molecules coordinated to a Ag^{+}ion in the solid state. Comparisons with crystalline H_{2}O and SO_{2}solvates of other Ag^{+}and K^{+}salts of weakly coordinating anions show that (i) N[(SO_{2})_{2}(1,2-C_{6}H_{4})]^{−}, BF_{4}^{–}, SbF_{6}^{–}, and Al(OC(CF_{3})_{3})_{4}^{–}coordinate much more strongly to Ag^{+}than does Y^{2–}, (ii) SnF_{6}^{2–}coordinates somewhat more strongly to K^{+}than does Y^{2–}, and (iii) B_{12}Cl_{12}^{2–}coordinates to K^{+}about the same as, if not slightly weaker than, Y^{2–}.