Synthesis and Characterization of a New Hybrid Polyoxometalate Compound: Bis(3-aminopropyl)ammonium Hexatungstotellurate(VI) Octahydrate

Abstract

Synthesis strategy of hybrids Polyoxometalates have drawn a lot of attention owing to interesting. Herein, we describe, the one pot process used to synthesize a new hybrid polyoxotungstate, (C<sub>6</sub>H<sub>20</sub>N<sub>3</sub>)<sub>2</sub>[TeW<sub>6</sub>O<sub>24</sub>].8H<sub>2</sub>O, at a temperature of 200°C. This preparation was carried out by mixing equimolar amounts of H<sub>2</sub>WO<sub>4</sub>, C<sub>6</sub>H<sub>17</sub>N<sub>3</sub>, and H<sub>6</sub>TeO<sub>6</sub>. The compound was characterized by infrared and UV-visible spectroscopy techniques, as well as by X-ray diffraction. The compound crystallizes in the monoclinic system with the space group P2<sub>1</sub>/c. The unit cell are: a = 8.74874(14) Å, b = 12.5894(2) Å, c = 18.5176(3) Å, α = 90°, β = 92.6078(14)°, γ = 90°. The compound consists of a non-protonated Anderson-type heteropolyanion [TeW<sub>6</sub>O<sub>24</sub>]<sup>6-</sup> stabilized by two organoammonium cations [C<sub>6</sub>H<sub>20</sub>N<sub>3</sub>]<sup>3+</sup> and eight water molecules. The polyoxoanion [TeW<sub>6</sub>O<sub>24</sub>]<sup>6-</sup> adopts an Anderson-Evans type structure of class A. Thus, the polyanion is bult of six {WO<sub>6</sub>} units surrounding a {TeO<sub>6</sub>} octahedron. The six {WO<sub>6</sub>} are linked together by edges sharing and connected around the heteroatom, via oxygen atoms, forming a planar structure with approximate D3d symmetry. The cohesion of the three-dimensional structure is ensured by hydrogen bonds between the polyanions, the organoammonium groups, and the water molecules, thereby providing significant stability to the compound. UV–Visible absorption spectroscopy shows a strong absorption band at 296nm attributed to Ligand-Metal Charge Transfer (LMCT) transition of the O→W and the main IR absorption bands of the polyanion appear at: 942 cm⁻¹, 875 cm⁻¹, 766 cm⁻¹ and 599 cm-¹.