Anion inclusion without auxiliary hydrogen bonds: X-ray structure of the iodide cryptate of a macrotricyclic tetra-quaternary ammonium receptor

Abstract

The X-ray Crystal and molecular structure of [I^–L⁴⁺]³⁺ 3I^–˙3MeCN·H₂O, L = N₄Me₄(C₆H₁₂)₆, shows on iodide anion to be encapsulated symmetrically into the spherical intramolecular cavity of the macrotricycle L⁴⁺ and held in place by the ectrostatic potential of the four quaternary ammonium sites arranged at the corners of an almost perfect tetrahedron; the N⁺⋯ I^– distances average to 4.54(2)Å whereas the distances between iodide and the carbon atoms of the [CH₂]₆ chains are of van der Waals type or longer.