Evidence of New Fluorinated Coordination Compounds
in the Composition Space Diagram of FeF<sub>3</sub>/ZnF<sub>2</sub>–H<i>amtetraz</i>-HF<sub>aq</sub> System
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Abstract
The
exploration of the composition space diagram of the FeF<sub>3</sub>/ZnF<sub>2</sub>–H<i>amtetraz</i>-HF<sub>aq</sub> system (H<i>amtetraz</i> = 5-aminotetrazole) by solvothermal
synthesis at 160 °C for 72 h in dimethylformamide (DMF) has evidenced
five new hybrid fluorides (<b>1</b>–<b>5</b>);
the structures are characterized from single crystal X-ray diffraction
data. [H<i>dma</i>]·(ZnFe<sup>III</sup>(H<sub>2</sub>O)<sub>4</sub>F<sub>6</sub>) (<b>1</b>) and [H<i>dma</i>]·[H<i>gua</i>]<sub>2</sub>·(Fe<sup>III</sup>F<sub>6</sub>) (<b>2</b>) contain anionic inorganic
chains (<b>1</b>) or isolated octahedra (<b>2</b>) weakly
hydrogen bonded (Class I hybrids) to dimethylammonium (H<i>dma</i>) and/or guanidinium (H<i>gua</i>) cations which are produced
from the tetrazole ligand and solvent decomposition. [H<i>dma</i>]<sub>2</sub>·[H<i>gua</i>]·[NH<sub>4</sub>]·[ZnFe<sup>III</sup>F<sub>5</sub>(<i>amtetraz</i>)<sub>2</sub>]<sub>2</sub> (<b>3</b>), [H<i>dma</i>]<sub>2</sub>·[Zn<sub>1.6</sub>Fe<sup>II</sup><sub>0.4</sub>Fe<sup>III</sup>F<sub>6</sub>(<i>amtetraz</i>)<sub>3</sub>] (<b>4</b>), and [H<i>dma</i>]·[Zn<sub>4</sub>F<sub>5</sub>(<i>amtetraz</i>)<sub>4</sub>] (<b>5</b>) are considered as Class II hybrids in which the (<i>amtetraz</i>)<sup>−</sup> anions are strongly linked
to divalent metal cations via N–M bonds. In <b>3</b>, <sub>∞</sub>{[NH<sub>4</sub>]·[ZnFe<sup>III</sup>F<sub>5</sub>(<i>amtetraz</i>)<sub>2</sub>]<sub>2</sub>} layers are separated by [H<i>dma</i>]<sup>+</sup> and
[H<i>gua</i>]<sup>+</sup> cations. <b>4</b> and <b>5</b> exhibit three-dimensional (3D) hybrid networks that contain
small cavities where [H<i>dma</i>]<sup>+</sup> cations are
inserted. A porous 3D metal–organic framework intermediate
is evidenced from the thermogravimetric analysis and X-ray thermodiffraction
of <b>5</b>