In 1983, Sauvage and co-workers reported the use of a metal ion to template the formation of a catenane in high yield . Their seminal Cu-phenanthroline motif inspired the development of a great many other metal directed syntheses of catenanes, rotaxanes and knots which, alongside passive templates based on other non-covalent interactions , have revolutionized the synthesis of interlocked molecules. A biproduct of this progress has been that a great many mechanically chelating ligandsmolecules in which two or more of the covalent subcomponents provide donor atomshave been described with denticities varying from 2 to 9 . However, the interlocked metal complexes themselves are typically intermediates in the synthesis rather than targets in their own right; the metal ion is simply removed once the mechanical bond has been formed to give the metal-free ligand, which is then studied or applied in other contexts. This is perhaps an oversight. As early as 1985 it was noted that the cavitand-like nature of the pocket formed between the interlocked sub-components, into which the donor atoms are projected, led to kinetically stabilized complexes . This "catenand" effect was attributed to the sterically crowded environment of the mechanical bond that prevented coordination of additional ligands to the metal ion as part of an associative ligand displacement process. Similarly, the confined environment of the mechanical bond was found to disfavor higher oxidation states of the metal ion, presumably by preventing coordination of exogenous anionic ligands . More recently, we have observed the remarkable stabilization of a Cu I organometallic species within the cavity of a rotaxanes as well as the stabilization of Pt II -luminophores against ligand displacement and oxidation , demonstrated that the mechanical bond allows access to complexes the non-interlocked equivalent of which are inaccessible , and used this insight to produce unusual interlocked Co II -based single ion magnets . We and others have also observed that, by hindering some reaction pathways, the mechanical bond can allow hidden reactivity of metal ions to emerge . Based on these observations, we have proposed that the mechanical bond might be used to control the properties of metal ions for a range of applications, from materials to catalysis .