Crown‐Ether‐Like Structures Derived from a Ti8O8(Carboxylate)16 Metallacycle

Mixed‐metal clusters have been obtained from the reaction of titanium alkoxides with either strontium or lead acetate and methacrylic acid. The structures of the clusters are derived from the metallacycle Ti₈O₈(methacrylate)₁₆. The Sr and Pb atoms in Sr₂Ti₈O₈X₂(OOCMe)₂(methacrylate)₁₆ (X: acetate or OiPr) and Pb₂Ti₈O₈(OBu)₂X₂(methacrylate)₁₆(BuOH)₂ (X: acetate or methacrylate) occupy the central cavity of the Ti₈O₈ ring. In addition to the crown‐ether‐like coordination of the ring oxygen atoms to the Sr or Pb atoms, bridging carboxylate ligands support the coordination of the latter atoms. In the compound Pb₂Ti₆O₅(OiPr)₃X(methacrylate)₁₄ (X: OiPr or methacrylate), the lead atoms are coordinated by a fragment of the Ti₈O₈(methacrylate)₁₆ metallacycle.