Syntheses and characterization of α-Keggin- and α 2 -Dawson-type diplatinum(II)-coordinated polyoxotungstates: Effects of skeletal structure, internal element, and nitrogen-containing ligand coordinated to the platinum center for hydrogen production from water under light irradiation

•Syntheses and characterization of α-Keggin- and α2-Dawson-type diplatinum(II)-coordinated polyoxotungstates.•Hydrogen evolution from aqueous TEOA solution under light irradiation in the presence of diplatinum(II) complex and eosin Y.•Cs6[α2-P2W17O61{cis-Pt(NH3)2}2]∙13H2O (Cs-P2W17-Pt-NH3) exhibited the highest activities.•Cs-P2W17-Pt-NH3 suppressed the decomposition of eosin Y, with faster formation of the heteropoly blue species.