Cover Picture (Angew. Chem. Int. Ed. Engl. 4/1986)

The cover shows the structure of a complex in which, for the first time, cyclo-P₅ could be stabilized. The planar cyclo-P₅ forms the middle layer of a tripledecker complex, which is completed by two chromium atoms and two pentamethyecyclopentadienyl ligands. Since a cyclo-P₆ complex (“hexaphosphabenzene”) was synthesized last year by the same research group and since cyclo-P₄ (“tetraphosphabutadine”) also be stabilized in a complex? Further details on the cyclo-P₅ complex are reported by O. J. Scherer et al. on page 363ff.