Structure D 2000Polar Domains and Charge-Density Waves in the Acentric Cerium(III) Iron(II) Sulfide Ce 22 Fe 21 S 54 . -The title compound is prepared from mixtures of Ce 2 S 3 and FeS in a ratio of 1:2 using LiCl/KCl as a flux (sealed silica tube, 1170 K, 6 d). Ce22Fe21S54 crystallizes in the monoclinic space group Cm with Z = 2 (single crystal XRD). The structure is a superstructure of the La2Fe2S5 structure type. Trans-edge-sharing [FeS6] octahedra form linear chains, which are isotactically capped on one side by [FeS4] tetrahedra. The polarity of the resulting ∞ 1 [Fe 2 S 5 ] chains is transferred to the entire structure, as the unit cell contains two layered domains of opposite polarity with the unbalanced size ratio of 4:6. -(MILLS, A. M.; RUCK*, M.; J. Solid State Chem. 181 (2008) 11, 3131-3136; Fachbereich Chem.,