Crystal structure of Sc(1.91)In(1.39)Mo(15)Se(19), containing Mo(6) and Mo(9) clusters

The structure of scandium indium penta­deca­molybdenum nona­deca­selenide, Sc(1.91)In(1.39)Mo(15)Se(19), is isotypic with In(2.9)Mo(15)Se(19) [Grüttner et al. (1979 ▸). Acta Cryst. B35, 285–292]. It is characterized by two cluster units Mo(6)Se(i) (8)Se(a) (6) and Mo(9)Se(i) (11)Se(a) (6) (where i represents inner and a apical atoms) 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—Se bonds. Sc—Se and In—Se bonds complete the structural set-up. In the title compound, the Sc(3+) cations replace the trivalent indium atoms present in In(2.9)Mo(15)Se(19), and a deficiency is observed at the monovalent indium site. One Mo, one Se and the Sc atom are situated on mirror planes, whereas two other Se atoms and the In atom are situated on threefold rotation axes.