Tuning the Size and Geometry of Heteroleptic Coordination Cages by Varying the Ligand Bent Angle

Spherical assemblies of the type [PdnL2n]2n+ can be obtained from PdII salts and curved N‐donor ligands, L. It is well established that the bent angle, α, of the ligand is a decisive factor in the self‐assembly process, with larger angles leading to complexes with a higher nuclearity, n. Herein, we report heteroleptic coordination cages of the type [PdnLnL′n]2n+, for which a similar correlation between the ligand bent angle and the nuclearity is observed. Tetranuclear cages were obtained by combining [Pd(CH3CN)4](BF4)2 with 1,3‐di(pyridin‐3‐yl)benzene and ligands featuring a bent angle of α=120°. The use of a dipyridyl ligand with α=149° led to the formation of a hexanuclear complex with a trigonal prismatic geometry; for linear ligands, octanuclear assemblies of the type [Pd8L8L′8]16+ were obtained. The predictable formation of heteroleptic PdII cages from 1,3‐di(pyridin‐3‐yl)benzene and different dipyridyl ligands is evidence that there are entire classes of heteroleptic cage structures that are privileged from a thermodynamic point of view. Angling for the right result: Heteroleptic Pd cages containing two types of dipyridyl ligands are described. The common feature of these complexes is the presence of two 1,3‐di(pyridin‐3‐yl)benzene ligands (depicted in gray). By varying the ligand bent angle, α, of the second ligand, we were able to able to increase the nuclearity of the assembly from 4 to 8.