Rational Design of a Face-Centred Square-Cuboid Coordination Cage

The simple synthetic conversion of a 90 degrees-angled bis-pyridyl ligand into a tripodal tris-pyridyl ligand leads to the formal transformation of a cubic (a = b = c) into a square-cuboid (a = b not equal c) coordination cage. Mathematical considerations associated with the ligand design, together with X-ray structure results, NMR spectroscopic and mass spectrometric characterization and molecular modeling of both coordination cages are presented and discussed.