Macrocyclic and open-chain ligands with the redox switchable trithiadiazapentalene unit: synthesis, structures and complexation phenomena

This review focuses on synthesis, structure and binding properties of crown compounds and their open-chain analogues containing a trithiadiazapentalen e building block. This heterocyclic unit favours in particular the complexa tion and solvent extraction of the soft transition metal ions Ag(I), Pd(II) , Hg(II) and Au(III). The redox active system trithiadiazapent alene/trithi otriuret introduced into a crown ring allows the control of Ag(I) and Hg(II ) phase transfer in solvent extraction experiments. Crystal structures of m etal complexes with these pentaleno crown compounds show significant differ ences of both S S bond lengths of the trithiadiazapentalene unit and packag e arrangements in the cell. (C) 2001 Elsevier Science B.V. All rights reser ved.