Complex Uranyl Dichromates Templated by Aza-Crowns
oleh: Oleg I. Siidra, Evgeny V. Nazarchuk, Dmitry O. Charkin, Stepan N. Kalmykov, Anastasiya I. Zadoya
| Format: | Article |
|---|---|
| Diterbitkan: | MDPI AG 2018-12-01 |
Deskripsi
Three new uranyl dichromate compounds templated by aza-crown templates were obtained at room temperature by evaporation from aqueous solutions: (H<sub>2</sub>diaza-18-crown-6)<sub>2</sub>[(UO<sub>2</sub>)<sub>2</sub>(Cr<sub>2</sub>O<sub>7</sub>)<sub>4</sub>(H<sub>2</sub>O)<sub>2</sub>](H<sub>2</sub>O)<sub>3</sub> (<b>1</b>), (H<sub>4</sub>[15]aneN<sub>4</sub>)[(UO<sub>2</sub>)<sub>2</sub>(CrO<sub>4</sub>)<sub>2</sub>(Cr<sub>2</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)] (H<sub>2</sub>O)<sub>3.5</sub> (<b>2</b>) and (H<sub>4</sub>Cyclam)(H<sub>4</sub>[15]aneN<sub>4</sub>)<sub>2</sub>[(UO<sub>2</sub>)<sub>6</sub>(CrO<sub>4</sub>)<sub>8</sub>(Cr<sub>2</sub>O<sub>7</sub>)<sub>4</sub>](H<sub>2</sub>O)<sub>4</sub> (<b>3</b>). The use of aza-crown templates made it possible to isolate unprecedented and complex one-dimensional units in <b>2</b> and <b>3</b>, whereas the structure of <b>1</b> is based on simple uranyl-dichromate chains. It is very likely that the presence of relatively large organic molecules of aza-crown ethers does not allow uranyl chromate chain complexes to condense into the units of higher dimensionality (layers or frameworks). In general, the formation of <b>1</b>, <b>2</b>, and <b>3</b> is in agreement with the general principles elaborated for organically templated uranyl compounds. The negative charge of the [(UO<sub>2</sub>)(Cr<sub>2</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)]<sup>2−</sup>, [(UO<sub>2</sub>)<sub>2</sub>(CrO<sub>4</sub>)<sub>2</sub>(Cr<sub>2</sub>O<sub>7</sub>)<sub>2</sub>(H<sub>2</sub>O)]<sup>4−</sup> and [(UO<sub>2</sub>)<sub>3</sub>(CrO<sub>4</sub>)<sub>4</sub>(Cr<sub>2</sub>O<sub>7</sub>)<sub>2</sub>]<sup>6−</sup> one-dimensional inorganic motifs is compensated by the protonation of all nitrogen atoms in the molecules of aza-crowns.