K+···Cπ and K+···F Non-Covalent Interactions in π-Functionalized Potassium Fluoroalkoxides
Abstract
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+C interactions with tethered ligands, are reported. A potassium-arene, a rare potassium-alkyne, and a potassium-olefin complex have been prepared by deprotonation of functionalized ,-bis(trifluoromethyl)alcohols with KN(SiMe2R)(2). They all feature a cuboid K4O4 core with (3)-bridging O atoms, and multiple stabilizing K+F contacts in the range 2.71-3.33 angstrom. The potassium-arene complex shows (2), (3), and (6) K+C (arene) interactions in the range 3.35-3.47 angstrom. The potassium-alkyne and potassium-olefin compounds are stabilized by (2) interactions with the unsaturated carbon-carbon bond, in the range 3.17-3.49 angstrom and 3.15-3.19 angstrom, respectively. Comparison with the parent complex devoid of a flanking ligand illustrates the role of K+C interactions.
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