Binuclear cryptates

Lehn, J.-M. Pine, S. H. Watanabe, E. I. Willard, A. K. Binuclear cryptates. Synthesis and binuclear cation inclusion complexes of bis-tren macrobicyclic ligands, J. Am. Chem. Soc. 1977, 99, 6766-6768. 

Crowns bridged on both sides form ditopic receptor molecules that form binuclear cryptate complexes (e.g. (30)). The preparation is normally accomplished by treatment of a diazacrown with a diacid chloride. Reduction of the tetralactam affords the tetraamine <73AG(E)579,77JA8502,79CC309). In particular, these structures have been probed by Sutherland and co-workers who assessed intramolecular diammonium cation binding by use of the NMR technique <79CC309>. 

The binuclear Co(n) cryptate (monohydroxo bridged) was also found to combine reversibly with dioxygen yielding a doubly-bridged cascade complex containing both hydroxo and peroxo bridges within the cryptate structure. 

As with amide hydrolysis reactions, extensive mechanistic studies of metal-mediated phosphate monoester hydrolysis reactions have been performed using exchange inert mononuclear Co(III) complexes.9,188-202 To date, only a few zinc complexes that promote phosphate monoester hydrolysis have been reported. A binuclear zinc complex supported by a macrocyclic cryptate ligand (Fig. 36)... 

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