Na(4.25)Mo(15)S(19): a novel ternary reduced molybdenum sulfide containing Mo(6) and Mo(9) clusters

The structure of tetra­sodium penta­deca­molybdenum nona­deca­sulfide, Na(4.25)Mo(15)S(19), is isotypic with Na(3.9)Mo(15)Se(19) [Salloum et al. (2013 ▶). Acta Cryst. E69, i67–i68]. It is characterized by Mo(6)S(i) (8)S(a) (6) and Mo(9)S(i) (11)S(a) (6) (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.