Self-Assembly of Thiacalix[4]arene-Supported Nickel(II)/Cobalt(II) Complexes Sustained by in Situ Generated 5-Methyltetrazolate Ligand

Solvothermal reactions of thiacalix[4]­arene, NaN₃, and acetonitrile in the presence of nickel­(II)/cobalt­(II) salts yielded four discrete complexes sustained by the in situ generated 5-methyltetrazolate ligand, [Ni^II₁₂(PTC4A)₃(μ₆-CO₃)₂(μ-Mtta)₂(μ-Mtta)₄ (μ₄-Mtta)₂(Py)₄]·7DMF·2Py·dma (<b>1</b>), [Co^II₁₂(PTC4A)₃(HCOO)₃(μ₆-CO₃)₂ (μ-Mtta)­(μ-Mtta)₂(μ₄-Mtta)₂(Py)₄]·5DMF·dma (<b>2</b>), [Co^II₁₂(BTC4A)₃(HCOO)₂ (μ₆-CO₃)₂(μ-Mtta)₄(μ₄-Mtta)₂(dma)₂(Pz)₂]·2DMF·3dma (<b>3</b>), and [Co^II₁₆(BTC4A)₄(μ₄-Cl)₄ (HCOO)₂(μ-Mtta)₆(μ-Mtta)₈]·10DMF·6CH₃CN·4Hdma (<b>4</b>) (H₄PTC4A = <i>p</i>-phenylthiacalix­[4]­arene; H₄BTC4A = <i>p</i>-tert-butylthiacalix­[4]­arene; HMtta = 5-methyl tetrazolate). Crystal structural analyses revealed that complexes <b>1</b>–<b>3</b> are stacked by pseudotrigonal planar entities, which consist of three metal^II₄-thiacalix­[4]­arene subunits including two shuttlecock-like and one cylinder-like ones. These subunits are connected in an up-to-down-to-up fashion through six different 5-methyl tetrazolate anions. Both the in situ generated 5-methyl tetrazolate anion and carbonato anion play an important role in constructing these high-nuclearity clusters. When the corresponding chloride salt was used as precursors in the synthesis, complex <b>4</b> was obtained, which is stacked by wheel-like entities possessing four shuttlecock-like building blocks linked by eight in situ generated 5-methyl tetrazolate ligands in an up-to-up fashion. The differences in the structures of complexes <b>3</b> and <b>4</b> indicate that the geometry and size of the corresponding anions together with their coordinating properties are essential in determining the final structures. The magnetic properties of complexes <b>1</b>–<b>4</b> were examined, indicating strong antiferromagnetic interactions between the nickel­(II)/cobalt­(II) ions in the temperature range of 50–300 K