Pentanuclear Ba(II) Complex of a Macrocyclic Ligand

We report here the first pentanuclear Ba(II) complex of a new tri-aza, tri-oxa macrocycle with two carboxymethyl “arms” pending from two N atoms, H₂L². The crystal structure corresponds to the formula [Ba₅(H_0.375L²)₄(ClO₄)(CH₃CH₂OH)(H₂O)₂](ClO₄)_2.5·9.5H₂O and reveals the presence of four molecules of the ligand surrounding five Ba(II) ions, giving rise to an unusual structure with the metal ions inside a spherical organic cavity.