Novel ‘anti-Prussian blue’ structure based on Zn2+ nodes and [Re3Mo3S8(CN)6]6− heterometallic cluster spacers and its rearrangement to Prussian blue

Abstract

The reaction between ZnCl₂ and an aqueous solution of CaK₄[Re₃Mo₃S₈(CN)₆]·8H₂O is controlled by the concentration of NH₃. High concentration of NH₃ favors the formation of [Zn(NH₃)₄]₈{Zn[Re₃Mo₃S₈(CN)₆]₃}·9H₂O with an ideal primitive cubic 3D network of Zn²⁺ cations joined by cyanocluster anions acting as unprecedented bulky linear spacers. The low concentration of NH₃ leads to the formation of the usual Prussian blue structure [Zn(NH₃)₄]₂[ZnRe₃Mo₃S₈(CN)₆]·2H₂O with alternating octahedral Zn²⁺ and cyanocluster nodes. Both compounds contain a paramagnetic cluster anion with g = 2.279 and 2.280, respectively. Powder diffraction studies prove that the former compound transforms into the latter after the exposure of a polycrystalline sample to air.