K⁺···Cπ and K⁺···F Non-Covalent Interactions in π-Functionalized Potassium Fluoroalkoxides Roşca, Sorin-Claudiu; Roueindeji, Hanieh; Dorcet, Vincent; Roisnel, Thierry; Carpentier, Jean-François; Sarazin, Yann
Secondary interactions stabilize coordinatively demanding complexes of s-block metals. The structures of potassium fluoroalkoxides that, in addition to intra- and intermolecular K⁺···F contacts, also exhibit K⁺···Cπ interactions with tethered π ligands, are reported. A potassium–arene, a rare potassium–alkyne, and a potassium–olefin complex have been prepared by deprotonation of functionalized α,α-bis(trifluoromethyl)alcohols with KN(SiMe₂R)₂. They all feature a cuboid K₄O₄ core with µ³-bridging O atoms, and multiple stabilizing K⁺···F contacts in the range 2.71–3.33 Å. The potassium–arene complex shows η², η³, and η⁶ K⁺···Cπ(arene) interactions in the range 3.35–3.47 Å. The potassium–alkyne and potassium–olefin compounds are stabilized by η² interactions with the unsaturated carbon–carbon bond, in the range 3.17–3.49 Å and 3.15–3.19 Å, respectively. Comparison with the parent complex devoid of a flanking π ligand illustrates the role of K⁺···Cπ interactions.
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