Encapsulating Ligands from More Than Two Components

3 Encapsulating Ligands from More Than Two Components 

The reactions discussed above are akin to those we considered in the early part of Chapter 6 and involve only two different types of reactant. In the final parts of the previous chapter, we illustrated the power of metal ions in building macrocyclic ligands from a variety of components in programmed, stepwise reactions. Can we apply the same principles to the assembly of encapsulating ligands  

7 The Three-Dimensional Template Effect, Supramolecular Chemistry and Molecular Topology 

As an example, consider the reaction of the cobalt(m) complex of 7.8 with formaldehyde and nitromethane to give 7.9, the cobalt(m) complex of ligand 7.10 (Fig. 7-10). Notice that 7.8 is the same precursor that we needed for the synthesis of 7.7. In the new ligand, 7.10, the cap is formed from three molecules of formaldehyde and one of nitromethane, and the capping atom is now the carbon of the CN02 group derived from the nitromethane. 

It is also possible to make rather more dramatic changes in the structure of the preformed capping group, and 7.11, the cobalt(n) complex of a functionalised triaza macrocyclic ligand, reacts with formaldehyde and nitromethane to give 7.12. 

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