Two Chloride Ions as a Template in the Formation of a Cyclic Hexaurea (pages 1648–1652)
Denys Meshcheryakov, Volker Böhmer, Michael Bolte, Véronique Hubscher-Bruder, Françoise Arnaud-Neu, Haiko Herschbach, Alain Van Dorsselaer, Iris Thondorf and Werner Mögelin
Article first published online: 2 FEB 2006 | DOI: 10.1002/anie.200503766
It takes two to template: A cyclic hexaurea with four xanthene and two diphenyl ether units is predominantly formed by reaction of two diisocyanate molecules with two diamine molecules in the presence of chloride (see picture; green Cl, blue N, red O). The formation of a 1:2 complex with chloride was confirmed by X-ray analysis, solution NMR spectroscopy, and ESI-MS. The complexation constants were determined by microcalorimetry and UV spectrometry.