Frontispiece: Reversible Mechanical Interlocking of D-Shaped Molecular Karabiners bearing Coordination-Bond Loaded Gates: Route to Self-Assembled [2]Catenanes.

Interlocked Coordination Rings. A series of D-shaped binuclear coordination rings are prepared by the self-assembly of two non-chelating bidentate ligands and a chosen cis-protected Pd(II) unit in 1:1:2 ratios under appropriate conditions. In their Full Paper on page 15174 ff., D. K. Chand et al. demonstrate the concentration-dependent dynamic equilibria (in water) between a given D-shaped ring and the corresponding interlocked pair of rings. The molecular species present in the equilibria are thoroughly characterized in spite of the intrinsic difficulties of such kind of systems.