CRYSTAL-STRUCTURE OF THE CRYPTAND [3.3.3] - POTASSIUM-IODIDE COMPLEX - A LARGE COORDINATION-NUMBER FOR POTASSIUM-ION

Cryptand [3.3.3] was prepared by a one-step process from 2 moles of 1, 11-diiodo-3,6,9-trioxaundecane and 1 mole of 1,11-diamino-3,6,9-trioxa undecane in acetonitrile using potassium carbonate as the base. An X-r ay crystal study of the KI-[3.3.3] complex shows that all cryptand don or atoms are directed towards the encapsulated K+. The K+ ion is not m idway between the two nitrogen atoms, but is 3.15 Angstrom from one ni trogen and 3.37 Angstrom from the other. The X-ray structure strongly suggests that potassium is coordinated by eleven donor atoms.