Construction of Pd-based coordination cages with three geometrically distinct ligands.

Three different dipyridyl ligands were combined with [Pd(CH 3 CN) 4 ](BF 4 ) 2 to give mixtures of homo- and/or heteroleptic coordination cages. The three ligands were chosen so that one ligand shows a parallel orientation of the coordinate vectors, the second ligand a bent angle of 60°, and the third ligand a bent angle of 120°. We have identified ligand mixtures that give rise to integrative self-sorting, and we have characterized a heterotrileptic [Pd 4 L 2 L' 2 L'' 4 ] 8+ cage by single crystal X-ray crystallography. The structural flexibility of ligands with alkynyl spacers was found to be of importance for the formation of heteroleptic complexes.