Dy0.64{Dy5[Fe2C9]}: A complex carbide with a composite structure

► The first successful refinement of a large composite structure Dy0.64{Dy5[Fe2C9]}. ► The presence of two kinds of complex anions with Fe as central atoms and C-ligands within this structure. ► The oxidation state of the Fe atoms are low, they can be assigned FeI and FeII.