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

• Published in: Inorganics 2019-02, Vol.7 (2), p.15
• Main Authors: Teillout, Anne-Lucie, de Oliveira, Pedro, Marrot, Jérôme, Howell, Robertha, Vilà, Neus, Walcarius, Alain, Mbomekallé, Israël
• Format: Article
• Language: English
• Subjects: Acetic acid; Analytical chemistry; Aqueous solutions; Catalysis; Catalytic oxidation; Chains; Chemical elements; Chemical reduction; Chemical Sciences; Chemical synthesis; Crystal structure; Decomposition; electro-catalysis; Electrochemistry; Electrodes; Fragments; Manganese; Manganese ions; NOx reduction; O2 reduction; Oxidation; Oxygen; pH effects; polyoxometalates; Single crystals; Sodium; Sodium tungstate; Structural analysis; Valence; WOC; X ray photoelectron spectroscopy; X-ray structure; XPS
• ISSN: 2304-6740; 2304-6740
• DOI: 10.3390/inorganics7020015

We present the synthesis and structural characterization of the manganese-containing polyoxotungstate, [(Mn(H2O)3)2(H2W12O42)]6− (1), obtained by reaction of MnCl2 with six equivalents of Na2WO4 in the presence of Zn(CH3COO)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 [H2W12O42]10− fragments are linked in pairs via Mn2+ ions, leading to linear chains of the form [(Mn(H2O)3)2(H2W12O42)]n6n−. The connection between chains occurs also via Mn2+ ions which bind [H2W12O42]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.