%0 Journal Article
%T Hydrogen Evolution from Water under Visible-Light Irradiation Using Keggin-Type Platinum(II)-Coordinated Phospho-, Silico-, and Germanotungstates as Co-Catalysts
%A Chika Nozaki Kato
%A Shunsaku Suzuki
%A Yuki Ihara
%A Koki Aono
%A Rie Yamashita
%A Keisuke Kikuchi
%A Tetsuji Okamoto
%A Hidemitsu Uno
%J Modern Research in Catalysis
%P 103-129
%@ 2168-4499
%D 2016
%I Scientific Research Publishing
%R 10.4236/mrc.2016.54010
%X The tetramethylammonium salts of diplatinum(II)
complexes composed of mono-lacunary Keggin-type silico and germanotungstates, [(CH<sub>3</sub>)<sub>4</sub>N]<sub>4</sub>[<i>¦Á</i>-SiW<sub>11</sub>O<sub>39</sub>{<i>cis</i>-Pt(NH<sub>3</sub>)<sub>2</sub>}<sub>2</sub>]&amp;middot;13H<sub>2</sub>O (TMA-Si-Pt)
and [(CH<sub>3</sub>)<sub>4</sub>N]<sub>4</sub>[<i>¦Á</i>-GeW<sub>11</sub>O<sub>39</sub>{<i>cis</i>-Pt(NH<sub>3</sub>)<sub>2</sub>}<sub>2</sub>]&amp;middot;11H<sub>2</sub>O (TMA-Ge-Pt),
were synthesized and crystallized. Single crystals of a tetramethylammonium
salt of Keggin-type diplatinum(II)-coordinated
phosphotungstate [(CH<sub>3</sub>)<sub>4</sub>N]<sub>3</sub>[<i>¦Á</i>-PW<sub>11</sub>O<sub>39</sub>{<i>cis</i>-Pt(NH<sub>3</sub>)<sub>2</sub>}<sub>2</sub>]¡Á10H<sub>2</sub>O (TMA-P-Pt) were also obtained. The X-ray structural analyses revealed that the two <i>cis</i>-platinum(II) moieties, [<i>cis</i>-Pt(NH<sub>3</sub>)<sub>2</sub>]<sup>2+</sup>,
were each coordinated to two oxygen atoms in a mono-vacant site of [XW<sub>11</sub>O<sub>39</sub>]<sup>(12-n)-</sup> (X<sup>n+</sup> = Si<sup>4+</sup>, Ge<sup>4+</sup>, P<sup>5+</sup>). FTIR
spectra of TMA-Si-Pt and TMA-Ge-Pt also suggested that the two platinum(II)
moieties were <span>coordinated to the vacant site
of [SiW<sub>11</sub>O<sub>39</sub>]<sup>8-</sup> and [GeW<sub>11</sub>O<sub>39</sub>]<sup>8-</sup>.
The <sup>1</sup>H NMR spectra in DMSO-<i>d</i><sub>6</sub> of TMA-Si-Pt and TMA-Ge-Pt
showed signals assigned to the two sets of NH<sub>3</sub> ligands coordinated to the platinum sites. These three
platinum compounds showed hydrogen
evolution from aqueous triethanolamine solution under visible light
irradiation (<i>¦Ë</i> ¡Ý 400 nm) in the presence of eosin Y, <i>¦Á</i>-Keggin mono-aluminum-substituted
silicotungstate, and titanium dioxide. The catalytic activities were influenced by the
central atoms, and TMA-P-Pt showed the highest activities among the three
platinum compounds.</span>
%K Polyoxometalates
%K Diplatinum(II) Complex
%K Hydrogen Evolution
%K Visible Light
%K X-Ray Crystallography
%U http://www.scirp.org/journal/PaperInformation.aspx?PaperID=70890