Single_Crystal_to_Single_Crystal Installation of Ln ₄ (OH) ₄ Cubanes in an Anionic Metallosupramolecular Framework

Abstract

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 [Rh4 Zn4 O(l-cys)12 ] (K6 [1]; l-H2 cys=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 (H2 O)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.