Crown ether analogues and their complexes. Solid-state and solution stereochemistry of dibenzo-15-crown-4 ether and its 2:2 complex with sodium iodide as studied by X-ray crystallography and NMR spectroscopic methods

Abstract

The structures of the title systems have been determined by X-ray crystallography. The sodium iodide complex has 2:2 stoichiometry and C_i symmetry. Each sodium cation coordinates to four oxygen atoms of one macrocyclic unit and one oxygen of the other 15-membered ring of the dimer. The 400 MHz ¹H NMR spectra have been analysed and assignments made on the basis of NOESY and COSY experiments. Solution ¹³C NMR spectra have been assigned using HETCOR methods. Solid-phase ¹³C NMR spectra are included and the results of sodium complexation on the solid-phase ¹³C chemical shifts are discussed. [4-²H₄] Dibenzo-15-crown-4 has been synthesized and employed as an aid in spectral assignments.