Macrocyclic ligands, complexation hard metal ions

Compartmental ligands (16) provide extensive opportunities for multiple metal ion complexation. An example of a mixed donor ligand incorporating different metal ions is the macrocyclic trinucleating hgand (63), which is capable of complexing two soft donor metal centers in addition to a hard alkali or alkaline earth metal. ... 

Many complexes of the group 1 metals prepared in non-aqueous conditions (e.g. in polar organic solvents) are known. Alkali metal ions are typically hard Lewis acids and favour coordination by hard O- and A-donor ligands. The use of macrocyclic ligands was detailed in Section 11.8, and in this section, we focus on examples of discrete molecular and polymeric species incorporating other types of O- and A-donors. The bonding in these types of compotuids is considered to be predominantly ionic. The use of stericaUy... 

---