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

Abstract

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, [NiII12(PTC4A)3(μ6-CO3)2(μ-Mtta)2(μ-Mtta)4 (μ4-Mtta)2(Py)4]·7DMF·2Py·dma (1), [CoII12(PTC4A)3(HCOO)3(μ6-CO3)2 (μ-Mtta)(μ-Mtta)2(μ4-Mtta)2(Py)4]·5DMF·dma (2), [CoII12(BTC4A)3(HCOO)2 (μ6-CO3)2(μ-Mtta)4(μ4-Mtta)2(dma)2(Pz)2]·2DMF·3dma (3), and [CoII16(BTC4A)4(μ4-Cl)4 (HCOO)2(μ-Mtta)6(μ-Mtta)8]·10DMF·6CH3CN·4Hdma (4) (H4PTC4A = p-phenylthiacalix[4]arene; H4BTC4A = p-tert-butylthiacalix[4]arene; HMtta = 5-methyl tetrazolate). Crystal structural analyses revealed that complexes 1–3 are stacked by pseudotrigonal planar entities, which consist of three metalII4-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 4 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 3 and 4 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 1–4 were examined, indicating strong antiferromagnetic interactions between the nickel(II)/cobalt(II) ions in the temperature range of 50–300 K.