A novel cesium-carborane cluster: Synthesis and structure of [Cs₅-(C₂B₉H₁₂)₄ Cl]_n

The cage degradation reaction of closo 1,2-C₂B₁₀H₁₂ carborane in the presence of 2-chloromethyl-4-nitro-phenol in alcoholic potassium hydroxide, followed by the addition of excess cesium chloride, produced a novel cesium carborane cluster, [Cs₅-(C₂B₉H₁₂)₄ Cl]_n, 1. The compound crystallizes in the tetragonal space group I-4 with a = 16.817(1) Å, b = 16.817(1) Å. c = 7.601(1) Å, V = 2149.6(3) Å, Z = 8 and calculated density of 1.906 Mg/m³. The final refinement converged at R = 0.018, based on 1142 unique reflections. There are two distinguishable type of cesium ions, Cs(l) is surrounded by four carborane cages and two Cl(1) ion, and Cs(2) is surrounded by five carborane cages and one Cl(1). The Cl occupies the center of a slightly distorted octahedral site Cs₆Cl, with two Cl(1)-Cs(1) average distance of 3.84 Å and four Cl(1)-Cs(2) average distance of 3.64 Å. Each unit is then linked to another through a Cs(1)-Cl-Cs(1)-Cl repeating unit forming a polymeric chain.