Single‐Crystal‐to‐Single‐Crystal Installation of Ln4(OH)4 Cubanes in an Anionic Metallosupramolecular Framework

Postsynthetic installation of lanthanide cubanes into a metallosupramolecular framework via a single‐crystal‐to‐single‐crystal (SCSC) transformation is presented. Soaking single crystals of K6[Rh4Zn4O(l‐cys)12] (K6[1]; l‐H2cys=l‐cysteine) in a water/ethanol solution containing Ln(OAc)3 (Ln3+=lanthanide ion) results in the exchange of K+ by Ln3+ with retention of the single crystallinity, producing Ln2[1] (2Ln) and Ln0.33[Ln4(OH)4(OAc)3(H2O)7][1] (3Ln) for early and late lanthanides, respectively. While the Ln3+ ions in 2Ln exist as disordered aqua species, those in 3Ln form ordered hydroxide‐bridged cubane clusters that connect [1]6− anions in a 3D metal‐organic framework through coordination bonds with carboxylate groups. This study shows the utility of an anionic metallosupramolecular framework with carboxylate groups for the creation of a series of metal cubanes that have great potential for various applications, such as magnetic materials and heterogeneous catalysts. Soaking crystals of K6[Rh4Zn4O(l‐cysteinate)12] in a lanthanide acetate solution results in the complete exchange of K+ with Ln3+ in a single‐crystal‐to‐single‐crystal process. For late lanthanides (Ln=Gd–Lu), this process afforded a series of lanthanide cubane clusters with a [Lu4(μ3‐OH)4]8+ core, which connect the RhIII4ZnII4 complex anions in a 3D MOF structure, showing magnetic cooling and heterogeneous catalytic abilities.