Self-Assembly of Thiacalix[4]arene-Supported Nickel(II)/Cobalt(II)
Complexes Sustained by in Situ Generated 5-Methyltetrazolate Ligand
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Abstract
Solvothermal reactions of thiacalix[4]arene, NaN<sub>3</sub>, 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<sup>II</sup><sub>12</sub>(PTC4A)<sub>3</sub>(μ<sub>6</sub>-CO<sub>3</sub>)<sub>2</sub>(μ-Mtta)<sub>2</sub>(μ-Mtta)<sub>4</sub> (μ<sub>4</sub>-Mtta)<sub>2</sub>(Py)<sub>4</sub>]·7DMF·2Py·dma
(<b>1</b>), [Co<sup>II</sup><sub>12</sub>(PTC4A)<sub>3</sub>(HCOO)<sub>3</sub>(μ<sub>6</sub>-CO<sub>3</sub>)<sub>2</sub> (μ-Mtta)(μ-Mtta)<sub>2</sub>(μ<sub>4</sub>-Mtta)<sub>2</sub>(Py)<sub>4</sub>]·5DMF·dma (<b>2</b>), [Co<sup>II</sup><sub>12</sub>(BTC4A)<sub>3</sub>(HCOO)<sub>2</sub> (μ<sub>6</sub>-CO<sub>3</sub>)<sub>2</sub>(μ-Mtta)<sub>4</sub>(μ<sub>4</sub>-Mtta)<sub>2</sub>(dma)<sub>2</sub>(Pz)<sub>2</sub>]·2DMF·3dma
(<b>3</b>), and [Co<sup>II</sup><sub>16</sub>(BTC4A)<sub>4</sub>(μ<sub>4</sub>-Cl)<sub>4</sub> (HCOO)<sub>2</sub>(μ-Mtta)<sub>6</sub>(μ-Mtta)<sub>8</sub>]·10DMF·6CH<sub>3</sub>CN·4Hdma (<b>4</b>) (H<sub>4</sub>PTC4A = <i>p</i>-phenylthiacalix[4]arene; H<sub>4</sub>BTC4A = <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<sup>II</sup><sub>4</sub>-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
