Fe4C crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in an L-shaped geometry to two equivalent Fe(4) and two equivalent C(1) atoms. In the second Fe site, Fe(2) is bonded in a 3-coordinate geometry to three equivalent Fe(4) and three equivalent C(1) atoms. In the third Fe site, Fe(3) is bonded in an L-shaped geometry to three equivalent Fe(4) and two equivalent C(1) atoms. In the fourth Fe site, Fe(4) is bonded in a 13-coordinate geometry to two equivalent Fe(1), three equivalent Fe(2), three equivalent Fe(3), four equivalent Fe(4), and one C(1) atom. C(1) is bonded in a 6-coordinate geometry to one Fe(4), two equivalent Fe(1), two equivalent Fe(3), and three equivalent Fe(2) atoms.
Fe4C crystallizes in the monoclinic P2_1/m space group. There are four inequivalent Fe sites. In the first Fe site, Fe(1) is bonded in an L-shaped geometry to two equivalent Fe(4) and two equivalent C(1) atoms. Both Fe(1)-Fe(4) bond lengths are 2.61 Å. Both Fe(1)-C(1) bond lengths are 2.01 Å. In the second Fe site, Fe(2) is bonded in a 3-coordinate geometry to three equivalent Fe(4) and three equivalent C(1) atoms. There is one shorter (2.50 Å) and two longer (2.51 Å) Fe(2)-Fe(4) bond lengths. There are two shorter (1.98 Å) and one longer (2.29 Å) Fe(2)-C(1) bond length. In the third Fe site, Fe(3) is bonded in an L-shaped geometry to three equivalent Fe(4) and two equivalent C(1) atoms. There is one shorter (2.43 Å) and two longer (2.58 Å) Fe(3)-Fe(4) bond lengths. Both Fe(3)-C(1) bond lengths are 1.98 Å. In the fourth Fe site, Fe(4) is bonded in a 13-coordinate geometry to two equivalent Fe(1), three equivalent Fe(2), three equivalent Fe(3), four equivalent Fe(4), and one C(1) atom. There are two shorter (2.64 Å) and two longer (2.65 Å) Fe(4)-Fe(4) bond lengths. The Fe(4)-C(1) bond length is 2.52 Å. C(1) is bonded in a 6-coordinate geometry to one Fe(4), two equivalent Fe(1), two equivalent Fe(3), and three equivalent Fe(2) atoms.