Three p-tert-Butylthiacalix[4]arene-Supported Cobalt Compounds Obtained in One Pot Involving In Situ Formation of N₆H₂ Ligand

Three p-tert-butylthiacalix[4]arene (H₄TC4A)-supported Co^II compounds, [Co₄(TC4A)(N₃)₄(N₆H₂)(CH₃OH)](CH₃OH)₂ (1), [Co₈(TC4A)₂(N₃)₂(N₆H₂)₂(CH₃COO)₄(CH₃OH)₄](OH)₂(CH₃OH)₄ (2), and [Co₁₀(TC4A)₄(N₃)₄](CH₃OH)₄ (3), have been solvothermally obtained in one pot and structurally characterized by single-crystal X-ray diffraction analyses, powder XRD, and IR spectroscopy. This work presents the first one-dimensional (1) cobalt cluster for the calixarene complexes and another two octanuclear (2) or decanuclear (3) cobalt clusters. In the structures of compounds 1 and 2, a novel N₆H₂ ligand formed by the in situ (2 + 3) cycloaddition of two azides was observed. Density functional theory (DFT) calculations give the heat of formation (2N₃⁻ + 2H⁺ → N₆H₂) and decomposition energy (N₆H₂ → 3N₂ + H₂) of 677.47 and 124.85 kcal/mol, respectively. Furthermore, an intergradation was determined at the B3LYP/6-311++g(d,p) level for the formation of the N₆H₂ ligand. In addition, one TC4A ligand of a sandwich unit adopts a cone conformation, while the other adopts a pinched cone conformation in 3. The magnetic properties of these three compounds were influenced mainly by the orbital contributions of the distorted octahedral Co^II ions.