The synthesis and characterization of a Keggin-type mono-rhenium(V)-substituted polyoxotungstate are described. The dimethylammonium salt [Me
2NH
2]
4[PW
11Re
VO
40] was obtained as analytically pure homogeneous black-purple crystals by reacting mono-lacunary Keggin polyoxotungstate with [Re
IV
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The synthesis and characterization of a Keggin-type mono-rhenium(V)-substituted polyoxotungstate are described. The dimethylammonium salt [Me
2NH
2]
4[PW
11Re
VO
40] was obtained as analytically pure homogeneous black-purple crystals by reacting mono-lacunary Keggin polyoxotungstate with [Re
IVCl
6]
2- in water, followed by crystallization from acetone at ca. 5 °C. Single-crystal X-ray structural analysis of [PW
11Re
VO
40]
4- revealed a monomeric structure with overall
Td symmetry. Characterization of [Me
2NH
2]
4[PW
11Re
VO
40] was also accomplished by elemental analysis, magnetic susceptibility, TG/DTA, FTIR, UV-vis, diffuse reflectance (DR) UV-vis, and solution
31P-NMR spectroscopy. Furthermore, [PW
11Re
VO
40]
4- and the Dawson-type dirhenium(V)-oxido-bridged polyoxotungstate [O{Re
V(OH)(α
2-P
2W
17O
61)}
2]
14- were supported onto anatase TiO
2 surface by the precipitation methods using CsCl and Pt(NH
3)
4Cl
2. With these materials, hydrogen evolution from water in the presence of EDTA⋅2Na (ethylenediamine tetraacetic acid disodium salt) under visible light irradiation (≥400 nm) was achieved.
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