Crystal Structure of FePb 4 Sb 6 Se 14 and its Structural Relationship with FePb 3 Sb 4 Se 10

Abstract

Single crystals of FePb 4 Sb 6 Se 14 , were obtained from solid‐state combination of high purity elemental powders at 873K for three days. Single crystal X‐ray structure determination revealed that the compound crystallizes in the monoclinic space group P 2 1 / c (no. 14) and adopts the structure of Jamesonite (FePb 4 Sb 6 S 14 ). The structure contains two crystallographically independent lead atoms with monocapped and bicapped trigonal prismatic coordinations, three antimony atoms located in a distorted octahedral environment and one iron atom occupying a flattened octahedral coordination. Neighboring monocapped and bicapped trigonal prims around lead atoms share faces and edges to build a corrugated layer parallel to the ac plane. Octahedrally coordinated antimony atoms share edges to form one‐dimensional (1D) {SbSe} ∞ ribbons connecting adjacent corrugated layers. The distortion of the octahedral coordination around antimony atoms within the {SbSe} ∞ ribbons with the longest bond pointing towards the center of the ribbon, suggests the stereochemical activity of antimony lone‐pairs with their electron clouds pointing towards the center of the {SbSe} ∞ ribbon. The three dimensional framework resulting from the connectivity between the corrugated layers and the {SbSe} ∞ ribbons, contains isolated cylindrical voids parallel to [100] which are filled by a 1D Fe n Se 4n+2 straight chain of edge‐sharing FeSe 6 octahedra. The crystal structure of FePb 4 Sb 6 Se 14 is closely related to that of FePb 3 Sb 4 Se 10 as they are formed by similar building units with different sizes.