Cover illustration: The asymmetric unit of rifampicin pentahydrate. Displacement ellipsoids are drawn at the 50% probability level. C-bound H atoms have been omitted. Hydrogen bonds are represented by dashed lines. See Wicher, Pyta, Przybylski, Tykarska & Gdaniec [Acta Cryst. (2012), C68, o209-o212].
Sc0.43Rb2Mo15S19 constitutes a partially Sc-filled variant of Rb2Mo15S19 containing an equal mixture of Mo6S8S6 and Mo9S11S6 cluster units. Extended Huckel tight-binding calculations provide an understanding of the variation in the Mo—Mo distances within the Mo clusters on the insertion of Sc.