Crystallographic and thermodynamic study of metal ion size selectivity in the ligand 1,4,7-triazacyclononane-N,N',N'-triacetate

The inclusion of a molecular species, viz. an attached ester function, inside a macrocyclic polymetallic toroid NiJSR),, as suggested first by Dahl,4 has been observed in Ni8- (SCH,COOEt),,, which is the first octagonal toroid. The sizes of toroidal molecules NiJSR),, are not dominated by the stereochemistry at Ni or SR but can be determined by factors such as steric repulsions between ligand substituents (p