ErFe2SiC crystallizes in the orthorhombic Cmcm space group. Er(1) is bonded in a 4-coordinate geometry to three equivalent Si(1) and four equivalent C(1) atoms. Fe(1) is bonded in a single-bond geometry to three equivalent Si(1) and one C(1) atom. Si(1) is bonded in a 9-coordinate geometry to three equivalent Er(1) and six equivalent Fe(1) atoms. C(1) is bonded to four equivalent Er(1) and two equivalent Fe(1) atoms to form a mixture of corner and edge-sharing CEr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 22°.
ErFe2SiC crystallizes in the orthorhombic Cmcm space group. Er(1) is bonded in a 4-coordinate geometry to three equivalent Si(1) and four equivalent C(1) atoms. There is one shorter (2.92 Å) and two longer (2.95 Å) Er(1)-Si(1) bond lengths. All Er(1)-C(1) bond lengths are 2.55 Å. Fe(1) is bonded in a single-bond geometry to three equivalent Si(1) and one C(1) atom. There are two shorter (2.35 Å) and one longer (2.36 Å) Fe(1)-Si(1) bond length. The Fe(1)-C(1) bond length is 1.77 Å. Si(1) is bonded in a 9-coordinate geometry to three equivalent Er(1) and six equivalent Fe(1) atoms. C(1) is bonded to four equivalent Er(1) and two equivalent Fe(1) atoms to form a mixture of corner and edge-sharing CEr4Fe2 octahedra. The corner-sharing octahedral tilt angles are 22°.