| Summary: | The structure of tetrasodium pentadecamolybdenum nonadecasulfide, Na4.25Mo15S19, is isotypic with Na3.9Mo15Se19 [Salloum et al. (2013). Acta Cryst. E69, i67–i68]. It is characterized by Mo6Si8Sa6 and Mo9Si11Sa6 (where i represents inner and a apical atoms) cluster units that are present in a 1:1 ratio. The cluster units are centered at Wyckoff positions 2b and 2c, and have point-group symmetry -3 and -6, respectively. The clusters are interconnected through additional Mo—S bonds. The Na+ cations occupy interunit voids formed by six or seven S atoms. One Mo, one S and one Na site [occupancy 0.751 (12)] are situated on mirror planes, and two other S atoms and one Na site (full occupancy) are situated on threefold rotation axes.
|
|---|
