The Assembly of Macrocyclic Bis‐ and Tetra‐β‐lactams with Embedded Platinum or Palladium Square‐Planar Centers

The synthesis, isolation, and full characterization of different types of stable, metal‐assembled macrocyclic β‐lactams are reported. By using adequately functionalized bis‐β‐lactams with defined stereochemistry as building blocks, a series of mono‐ and bimetallic Pd and Pt macrocycles has been prepared in good to quantitative yields. These novel structures combine the β‐lactam moiety with transition‐metal fragments with cis‐square‐planar geometry and constitute a new class of metal‐assembled cavities involving molecules with biological relevance as building blocks. By combining the adequate ligands, metallic fragments, and tuning the reaction conditions, different mono‐ and bimetallic macrocyclic β‐lactam cavities can be selectively obtained. Macrocycles with Pt–ethynyl groups are suitable to form host–silver triflate guest complexes in a tweezer fashion.