Single-Crystal-to-Single-Crystal Installation of Ln4(OH)4Cubanes 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 K-6[Rh4Zn4O(l-cys)(12)] (K-6[1];l-H(2)cys=l-cysteine) in a water/ethanol solution containing Ln(OAc)(3)(Ln(3+)=lanthanide ion) results in the exchange of K(+)by Ln(3+)with retention of the single crystallinity, producing Ln(2)[1] (2(Ln)) and Ln(0.33)[Ln(4)(OH)(4)(OAc)(3)(H2O)(7)][1] (3(Ln)) for early and late lanthanides, respectively. While the Ln(3+)ions in2(Ln)exist as disordered aqua species, those in3(Ln)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.