Structurally reinforced cyclen: a rigidly trans-co-ordinating twelve-membered macrocycle

Abstract

Reaction of 1,4,7,10-tetra-azacyclododecane (cyclen) with 1,2-dibromoethane connects an adjacent pair of secondary amino groups, by means of an ethano bridge, reinforcing the macrocycle and allowing it to circumscribe rigidly nickel(II); an ion to which it would normally be bound in a folded conformation.