Catenands, catenane ligands

When the copper complex of 7.62 reacts with ICH2(CH2OCH2)4CH2l in the presence of base, an intramolecular cyclisation occurs to form the macrocyclic ether 7.63. However, because of the arrangement of the starting ligands about the copper(i) centre, the two macrocycles are interlinked, and the consequence is the formation of the copper(i) complex of the catenand (catenand = catenane ligand) (Fig. 7-41). 

Two interlocked macrocyclic ligands as in (15) are topologically related to the catenanes, whence the name catenand derives.34,186 187 These macrocycles complex a variety of metals, presumably in a tetrahedral geometry.34,186 The stabilizing effect of the catenand topology is evident in the observed redox stability of the nickel(I) complex186 as well as the reluctance toward demetallation, observed for the copper(I) complexes.187... 

These complexes of catenands are remarkably stable. However, treatment of the complex with cyanide results in demetallation and the formation of the free catenane, in which the two macrocyclic ligands are still interlocked. There is a conformational change upon demetallation and in the solid state the rings have slipped . It is not trivial to estab-... 

In the first section, we will mention the early work done in the authors group, which led to a copper(I)-complexed [2]catenane in a preparative fashion and the corresponding ligand ( catenand ). A few X-ray structures (complexes and free catenane) will illustrate this section. 

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