Atomically Precise Crystalline Materials Based on Kinetically Inert Metal Ions via Reticular Mechanopolymerization

The incorporation of kinetically inert metal ions as structural elements in crystalline coordination polymers is a synthetic challenge. While a small family of materials based on inert ions has been prepared (i.e. Cr(III)-based MIL-100, MIL-101, and [Ru₆(btc)₄Cl₃]), general strategies that enable reticular synthesis have not been reported. Here we describe the mechanochemical synthesis of a reticular family of crystalline Ru₂[II,III]-based materials by polymerization of molecular Ru₂ complexes, featuring unprotected carboxylic acid substituents, with Cu(OAc)₂. The resulting crystalline heterobimetallic MOFs are solid-solutions of Ru₂ and Cu₂ sites housed within [M₃L₂] phases. The developed mechanochemical strategy is modular and allows for control of the primary coordination sphere of the Ru₂ sites. We anticipate the strategy will provide a rational approach to incorporation of kinetically inert ions in porous crystalline coordination networks, generating a class of atomically precise mixed-metal materials.