Syntheses, structures and properties of a series of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates

• Sandwich-type arsenotungstates
• 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates
• Electrocatalytic activities for the hydrogen peroxide reduction

A class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H2N(CH3)2]8H3[LnNa(H2O)4(OH)WO(H2O) (B-α-AsW9 O33)2]·8H2O [Ln = LaIII (1), CeIII (2), PrIII (3)] have been isolated from an aqueous solution reaction system (pH = 4) of Na2WO4·2H2O, C2H7N·HCl, NaAsO2 and Ln(NO3)3·6H2O and structurally characterized by elemental analyses, IR spectra, UV spectra and single-crystal X-ray diffraction. It is the most prominent in 1–3 that the [LnNa(H2O)4(OH) WO(H2O)(B-α-AsW9O33)2]11 − polyanion consists of two trivacant Keggin [B-α-AsW9O33]9 − moieties linked by one [WO(H2O)]4 + group and a dimeric [LnNa(H2O)4(OH)]3 + group resulting in the special 3s–5d–4f mixed metal substituted sandwich-type assembly. Interestingly, lanthanide and sodium ions simultaneously occupy the two positions located at the central belt of 1–3 with the site occupancy of 50% for each position. Moreover, the electrochemical and electrocatalytic properties of only 1 and 2 have been measured by cyclic voltammetry (CV) in 0.5 mol·L− 1 Na2SO4 + H2SO4 aqueous solution. 1 and 2 illustrate electrocatalytic activities for the hydrogen peroxide reduction.

Graphic abstractA class of 3s–5d–4f mixed metal substituted sandwich-type arsenotungstates [H2N(CH3)2]8H3[LnNa(H2O)4(OH) WO(H2O)(B-α-AsW9O33)2]·8H2O [Ln = La3 + (1), Ce3 + (2), Pr3 + (3)] have been synthesized and characterized.Figure optionsDownload as PowerPoint slide