Synthesis, Crystal Structure, Electrochemistry and Electro-Catalytic Properties of the Manganese-Containing Polyoxotungstate, [(Mn(H2O)3)2(H2W12O42)]6−

International audience ; We present the synthesis and structural characterization of the manganese-containing polyoxotungstate, [(Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] 6− (1), obtained by reaction of MnCl 2 with six equivalents of Na 2 WO 4 in the presence of Zn(CH 3 COO) 2 in acetate medium (pH 4.7). This has been assessed by various techniques (FTIR, TGA, UV-Visible, XPS, elemental analysis, single crystal X-ray and electrochemistry). Single-crystal X-ray analyses showed that, in the solid state, 1 forms a 2-D network in which [H 2 W 12 O 42 ] 10− fragments are linked in pairs via Mn 2+ ions, leading to linear chains of the form [(Mn(H 2 O) 3) 2 (H 2 W 12 O 42)] n 6n−. The connection between chains occurs also via Mn 2+ ions which bind [H 2 W 12 O 42 ] 10− fragments belonging to two adjacent chains, forming an infinite 2-D network. A complete electrochemical study was done in aqueous solution where 1 is stable in the pH range 1 to 6. This complex undergoes multiple electron-transfer processes that lead to the electro-generation of manganese high oxidation state species that catalyse water electro-oxidation. 1 is also effective in the electro-catalytic reduction of nitrite and dioxygen.