Directed Dehydration of Na₄Sn₂S₆ ⋅ 5H₂O Generates the New Compound Na₄Sn₂S₆: Crystal Structure and Selected Properties

The new thiostannate Na4Sn2S6 was prepared by directed crystal water removal from the hydrate ⋅ 5H2O at moderate temperatures. While structure of comprises isolated [Sn2S6]4− anions, that anhydrate contains linear chains composed corner-sharing SnS4 tetrahedra, a structural motif not known in chemistry. This rearrangement requires bond-breakage anion, movements fragments opened anion and Sn−S−Sn bond formation. Simultaneously, coordination environment Na+ cations is significantly altered situ formed NaS5 polyhedra are joined corner- edge-sharing to form six-membered ring. Time-dependent X-ray powder diffraction evidences very fast rehydration into during storage air atmosphere, but recovery initial crystallinity several days. Impedance spectroscopy demonstrates mediocre room-temperature ion conductivity 0.31 μS cm−1 an activation energy for ionic transport Ea=0.75 eV.