Supramolecular Frameworks Based on Rhenium Clusters Using the Synthons Approach
oleh: Nathalie Audebrand, Antoine Demont, Racha El Osta, Yuri V. Mironov, Nikolay G. Naumov, Stéphane Cordier
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2021-05-01 |
Deskripsi
The reaction of the K<sub>4</sub>[{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(OH)<sup>a</sup><sub>6</sub>]·8H<sub>2</sub>O rhenium cluster salt with pyrazine (Pz) in aqueous solutions of alkaline or alkaline earth salts at 4 °C or at room temperature leads to apical ligand exchange and to the formation of five new compounds: [<i>trans-</i>{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup><sub>2</sub>(H<sub>2</sub>O)<sup>a</sup><sub>2</sub>] (<b>1</b>), [<i>cis-</i>{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup><sub>2</sub>(H<sub>2</sub>O)<sup>a</sup><sub>2</sub>] (<b>2</b>), (NO<sub>3</sub>)[<i>cis-</i>{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup>(H<sub>2</sub>O)<sup>a</sup><sub>3</sub>](Pz)·3H<sub>2</sub>O (<b>3</b>), [Mg(H<sub>2</sub>O)<sub>6</sub>]<sub>0.5</sub>[<i>cis-</i>{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup><sub>3</sub>(H<sub>2</sub>O)<sup>a</sup>]·8.5H<sub>2</sub>O (<b>4</b>), and K[<i>cis</i>-{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup><sub>3</sub>(H<sub>2</sub>O)<sup>a</sup>]·8H<sub>2</sub>O (<b>5</b>). Their crystal structures are built up from <i>trans</i>- or <i>cis</i>-[{Re<sub>6</sub>S<sup>i</sup><sub>8</sub>}(Pz)<sup>a</sup><sub>2</sub>(OH)<sup>a</sup><sub>4−x</sub>(H<sub>2</sub>O)<sup>a</sup><sub>x</sub>]<sup>x−2</sup> cluster units. The cohesions of the 3D supramolecular frameworks are based on stacking and H bonding, as well as on H<sub>3</sub>O<sub>2−</sub>bridges in the cases of (<b>1</b>), (<b>2</b>), (<b>4</b>), and (<b>5</b>) compounds, while (<b>3</b>) is built from stacking and H bonding only. This evidences that the nature of the synthons governing the cluster unit assembly is dependent on the hydration rate of the unit.