Calix[4]arene-Analogous Technetium Supramolecules.

Calix[4]arene-analogous technetium supramolecules ( 1 and 2 ) were assembled using (NBu 4 )[Tc 2 (μ-Cl) 3 (CO) 6 ] and neutral flexible bidentate nitrogen-donor ligands (L 1 and L 2 ) consisting of four arene units covalently joined via methylene units. The neutral homoleptic technetium macrocycles adopt a partial cone/cone-shaped conformation in the solid state. These supramolecules are the first example of fac -[Tc(CO) 3 ] + core-based metallocalix[4]arenes and second example of fac -[Tc(CO) 3 ] + core-based metallomacrocycles. Structurally similar fac -[Re(CO) 3 ] + core-based macrocycles ( 3 and 4 ) were also prepared using [Re(CO) 5 X] (where X = Cl or Br) and L 1 or L 2 . The products were characterized spectroscopically and by X-ray analysis.