Mn3B4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent B(2) atoms. In the second Mn site, Mn(2) is bonded to four equivalent B(2) and eight equivalent B(1) atoms to form a mixture of edge and face-sharing MnB12 cuboctahedra. There are two inequivalent B sites. In the first B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Mn(2), five equivalent Mn(1), and two equivalent B(1) atoms. In the second B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Mn(1), four equivalent Mn(2), one B(1), and two equivalent B(2) atoms.
Mn3B4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent B(2) atoms. Both Mn(1)-B(1) bond lengths are 2.16 Å. There are four shorter (2.18 Å) and one longer (2.20 Å) Mn(1)-B(2) bond length. In the second Mn site, Mn(2) is bonded to four equivalent B(2) and eight equivalent B(1) atoms to form a mixture of edge and face-sharing MnB12 cuboctahedra. All Mn(2)-B(2) bond lengths are 2.36 Å. All Mn(2)-B(1) bond lengths are 2.27 Å. There are two inequivalent B sites. In the first B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Mn(2), five equivalent Mn(1), and two equivalent B(1) atoms. Both B(2)-B(1) bond lengths are 1.76 Å. In the second B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Mn(1), four equivalent Mn(2), one B(1), and two equivalent B(2) atoms. The B(1)-B(1) bond length is 1.72 Å.