Mn7C3 crystallizes in the orthorhombic Pnma space group. There are five inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 4-coordinate geometry to two equivalent C(1) and two equivalent C(2) atoms. In the second Mn site, Mn(2) is bonded in a distorted trigonal non-coplanar geometry to one C(2) and two equivalent C(1) atoms. In the third Mn site, Mn(3) is bonded in a distorted water-like geometry to two equivalent C(1) atoms. In the fourth Mn site, Mn(4) is bonded in a distorted trigonal planar geometry to one C(2) and two equivalent C(1) atoms. In the fifth Mn site, Mn(5) is bonded in a 3-coordinate geometry to one C(2) and two equivalent C(1) atoms. There are two inequivalent C sites. In the first C site, C(2) is bonded in a 6-coordinate geometry to one Mn(4), one Mn(5), two equivalent Mn(2), and four equivalent Mn(1) atoms. In the second C site, C(1) is bonded in a 7-coordinate geometry to one Mn(3), one Mn(4), one Mn(5), two equivalent Mn(1), and two equivalent Mn(2) atoms.
Mn7C3 crystallizes in the orthorhombic Pnma space group. There are five inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 4-coordinate geometry to two equivalent C(1) and two equivalent C(2) atoms. There is one shorter (2.04 Å) and one longer (2.21 Å) Mn(1)-C(1) bond length. There is one shorter (2.00 Å) and one longer (2.42 Å) Mn(1)-C(2) bond length. In the second Mn site, Mn(2) is bonded in a distorted trigonal non-coplanar geometry to one C(2) and two equivalent C(1) atoms. The Mn(2)-C(2) bond length is 2.02 Å. There is one shorter (1.99 Å) and one longer (2.03 Å) Mn(2)-C(1) bond length. In the third Mn site, Mn(3) is bonded in a distorted water-like geometry to two equivalent C(1) atoms. Both Mn(3)-C(1) bond lengths are 2.00 Å. In the fourth Mn site, Mn(4) is bonded in a distorted trigonal planar geometry to one C(2) and two equivalent C(1) atoms. The Mn(4)-C(2) bond length is 1.97 Å. Both Mn(4)-C(1) bond lengths are 1.96 Å. In the fifth Mn site, Mn(5) is bonded in a 3-coordinate geometry to one C(2) and two equivalent C(1) atoms. The Mn(5)-C(2) bond length is 1.92 Å. Both Mn(5)-C(1) bond lengths are 1.97 Å. There are two inequivalent C sites. In the first C site, C(2) is bonded in a 6-coordinate geometry to one Mn(4), one Mn(5), two equivalent Mn(2), and four equivalent Mn(1) atoms. In the second C site, C(1) is bonded in a 7-coordinate geometry to one Mn(3), one Mn(4), one Mn(5), two equivalent Mn(1), and two equivalent Mn(2) atoms.