Reversible Transformation between Cubane and Stairstep Cu 4 I 4 Clusters Using Heat or Solvent Vapor

The controlled self‐assembly of CuI and an asymmetric ligand with mixed N/S donors, 2‐( tert ‐butylthio)‐ N ‐(pyridin‐3‐yl)acetamide ( L ), afforded three Cu I coordination polymers (CPs), [Cu 4 I 4 L 2 (MeCN) 2 ] n ( 1 ), [Cu 4 I 4 L 2 ] n ( 2 ), and {[Cu 4 I 4 L 2 ] ⋅ MeOH} n ( 3 ). X‐ray analyses showed that CPs 1 – 3 are supramolecular isomers with 1, 2, and 3D structures, respectively. CP 1 adopts a stairstep Cu 4 I 4 cluster, whereas CPs 2 and 3 are composed of cubane‐like Cu 4 I 4 clusters. Crystal‐to‐crystal transformations of 1 to 2 and 3 showed reversible transformations between different Cu 4 I 4 clusters using heat or solvent (acetonitrile or methanol) vapor. CP 2 was reversibly transformed to 3 by the addition of methanol and heat. Therefore, the transformations between supramolecular isomers 1 , 2 , and 3 are completely reversible.