Oxidant-induced intramolecular triazole formation.

C3-symmetric ligands carrying a rigid triaminoguanidinium backbone are important building blocks for the preparation of supramolecular coordination cages as tetrahedra or trigonal bipyramides. Coordination of Eu(III)- or Gd(III)-ions leads to 1,2,4-triazole formation, which has been reported only rarely. Using Pd(II)-complexes as a model system, this triazole formation could be analyzed in more detail. The preparation of Pd(II)-coordination compounds can be easily done under stoichiometric control. These complexes could be transformed into 1,2,4-triazoles using O2 or H2O2 as an oxidation reagent. The steric demand of the PR3-coligand seems to play a key role in the cyclisation reaction.

Container molecules based on imine type ligands.

This chapter will give a short overview about container molecules, their synthesis and possible applications. The main focus is on those which are based on imine type ligands. These containers can be used for example for guest exchange, gas separation, as chemical sensors or for the stabilisation of white phosphorus under water. The described cages have wide openings or tightly closed ones. For one cage the reversible opening and closing is also described.