The cover shows a computer-graphics-drawn space-filling model of the structure, determined by X-ray diffraction, of the 1 : 1 adduct obtained from the neutral complex trans-[Pt(PMe3)Cl2(NH3)] and dibenzo-crown-6 (Pt yellow, P pink, Cl green, N blue, O red, C black-hatched, H white). The crown ether is anchored in the second coordination sphere of the Pt complex through NH ⃛O hydrogen bonds. The ligands in the second coordination sphere of transition-metal complexes can be bound by means of electrostatic forces, hydrogen bonds, charge-transfer interactions, or van der Waals forces. Further details on this phenomenon, which is also important for natural receptor molecules such as cyclodextrins and polyether antibiotics, are reported by J. F. Stoddart et al. on p. 487 ff.