Polydentate chalcogen bonding: anion trapping with a water-stable host compound carrying Se–CF3 functions

Abstract

Bidentate and tetradentate chalcogen bonding host systems with SeCF₃ functions as σ-hole donors in close proximity at the alkyne functions of 1,8-diethynylanthracene and its syn-dimer were prepared in quantitative yield by tin-selenium exchange reactions of the corresponding trimethylstannyl precursors with ClSeCF₃. The bidentate system shows chalcogen bonding interactions with THF, but does not bind halide ions. The tetradentate system cooperatively chelates chloride, bromide and iodide ions with its four CC–SeCF₃ units by rotating the four σ-holes towards the halide ion. The structures of these halide ion adducts were determined by X-ray diffraction. The hydrobromide and -iodide salts of the ethyl derivative of Schwesinger's phosphazene superbase served as halide salts with very weakly coordinating cations.