Cs[Cl₃ F₁₀ ]: A Propeller-Shaped [Cl₃ F₁₀ ]^- Anion in a Peculiar A^[5] B^[5] Structure Type

Reaction of CsF with ClF₃ leads to Cs[Cl₃ F₁₀ ]. It contains a molecular, propeller-shaped [Cl₃ F₁₀ ]^- anion with a central μ₃ -F atom and three T-shaped ClF₃ molecules coordinated to it. This anion represents the first example of a heteropolyhalide anion of higher ClF₃ content than [ClF₄ ]^- and is the first Cl-containing interhalogen species with a μ-bridging F atom. The chemical bonds to the central μ₃ -F atom are highly ionic and quite weak as the bond lengths within the coordinating XF₃ units (X = Cl, and also calculated for Br, I) are almost unchanged in comparison to free XF₃ molecules. Cs[Cl₃ F₁₀ ] crystallizes in a very rarely observed A^[5] B^[5] structure type, where cations and anions are each pseudohexagonally close packed, and reside, each with coordination number five, in the trigonal bipyramidal voids of the other.