Adamanzanes—bi- and tricyclic tetraamines and their coordination compoundsElectronic supplementary information (ESI) available: tables of variations in Nax–M–Nax angles as a function of cavity size and the radius of the central ion. See http://www.rsc.org/suppdata/dt/b3/b300510k/

Abstract

Structural modification of the important tetraaza macrocyclic ligands such as cyclen and cyclam involving ethylene and trimethylene bridging of the non-adjacent nitrogens represents a new class of macrobicyclic ligands, so-called bowl-adamanzanes. The molecular topology and size confer special properties to these amines and the most prominent features of their metal ion coordination complexes are extreme inertness and stabilization of low oxidation states. Strapping of the two secondary amine groups in the bicyclic bowl-adamanzanes leads to tricyclic tetraamine cages. These so-called cage-adamanzanes present themselves as interesting molecules with extreme acid–base properties important to model systems within biochemistry and applications such as suitable counter-ions for stablizing alkalides.