Two Electrocatalytic Selenoarsenates with Manganese Complex Cations as Counterions.

The discovery of new organic hybrid chalcogenidometalates is of great importance for structural chemistry and functional material. Here, new types of organic hybrid selenoarsenates [Mn(dien) 2 ] 2 [As II 4 Se 6 ] ( 1 , dien = diethylenetriamine) and [Mn(dien) 2 ] 2 [Mn(As III Se 3 ) 2 ] ( 2 ) have been solvothermally synthesized by the reaction of K 3 AsO 3 , Se, and MnCl 2 · x H 2 O ( x = 0, 2) in dien solution at 120 °C. 1 presents a hitherto unknown [As II 4 Se 6 ] 4- anion with low-valent As 2+ ion, which comprises a centrosymmetric six-membered [As II 4 Se 2 ] ring in chair-like conformation, while 2 contains a new type of heterometallic selenoarsenate(III) [Mn(As III Se 3 ) 2 ] 4- constructed by the connection of one tetrahedral [MnSe 4 ] and two rare noncondensed [As III Se 3 ] 3- anions. 1 and 2 were first combined with nickel nanoparticle (Ni) and the nickel foam (NF) for fabricating the 1 /Ni/NF and 2 /Ni/NF electrodes, which exhibited excellent oxygen evolution reaction electrocatalytic property with a low overpotential of 248 mV for 1 and 219 mV for 2 at 10 mA cm -2 in alkaline media.