Stepwise Halide‐Triggered Double and Triple Catenation of Self‐Assembled Coordination Cages

Abstract A simple self‐assembled [Pd 2 L 4 ] coordination cage consisting of four carbazole‐based ligands was found to dimerize into the interpenetrated double cage [3 X@Pd 4 L 8 ] upon the addition of 1.5 equivalents of halide anions (X=Cl − , Br − ). The halide anions serve as templates, as they are sandwiched by four Pd II cations and occupy the three pockets of the entangled cage structure. The subsequent addition of larger amounts of the same halide triggers another structural conversion, now yielding a triply catenated link structure in which each Pd II node is trans‐coordinated by two pyridine donors and two halide ligands. This simple system demonstrates how molecular complexity can increase upon a gradual change of the relative concentrations of reaction partners that are able to serve different structural roles.