Aufbau synthesis of a mixed-metal anion receptor cage

The isolation and structural characterisation of square planar [Ni(atu)(2)] (Hatu = amidinothiourea) has provided a rational basis to synthesise the n ovel mixed-metal cage compounds [Ni4Pd2(atu)(8)X]X-3 (X = Cl, Br); one of t hese cages (when X = Cl) has been crystallographically characterised showin g that the chloride anion is encapsulated in the centre of the cage forming eight hydrogen-bonds with N-H groups from the ligands and two Lewis acid-b ase interactions with two palladium(II) ions.