Europium antimony sulfide, Eu6Sb6S17

Eu6Sb6S17 is isotypic with Sr6Sb6S17 and can be regarded as consisting of two isolated [Sb3S7]5− anions and an S32− polysulfide anion that are joined together by Eu2+ cations. There are six crystallographically unique Eu2+ cations bound by sulfide and polysulfide anions in seven‐, eight‐ and nine‐coordinate environments. Each of the [Sb3S7]5− anions consists of a trinuclear assembly of corner‐sharing SbS3 units. The [Sb3S7]5− anions are connected by long (3.1 Å) Sb—S inter­actions, forming one‐dimensional ribbons running down the a axis and packed with opposing directions of polarity. The bent S32− anions stack in columns parallel to the a axis, oriented in opposing directions with respect to one another. The overall structure is three‐dimensional and has channels running down the a axis to house the stereochemically active lone pair of electrons on the Sb3+ centers. The presence of Eu2+ is supported by both magnetic measurements and bond‐valence calculations.