Low Symmetry Cage Complexes Formed by Metalation of Symmetric Hexa-Cationic Organic Cages.

Most metal organic cages are assembled through metal-ligand coordination, resulting in cages where the metal ions are part of the cage architecture, and thus have limited reactivity. There are only a handful of metal organic cages produced by metalation of a pre-synthesised organic cage. In this work, we show that hexa-cationic hydrazone cages coordinate a range of transition metal ions upon deprotonation to give cage complexes with metal ions oriented towards the cage cavity. Remarkably, a cage with ethyl solubilising groups gives the expected three-fold symmetric metallocage, cages with alkoxy solubilising groups give low-symmetry zinc metallocages, and a cage without a solubilising group switches between high and low symmetry conformations depending on solvent. These low symmetry arrangements persist on the NMR timescale at temperatures as high as 360 K and in the presence of a wide range of anions.