posted on 2012-06-06, 00:00authored byKecai Xiong, Feilong Jiang, Yanli Gai, Zhangzhen He, Daqiang Yuan, Lian Chen, Kongzhao Su, Maochun Hong
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.