Ta3B4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent B(2) atoms. In the second Ta site, Ta(2) is bonded to four equivalent B(2) and eight equivalent B(1) atoms to form a mixture of face and edge-sharing TaB12 cuboctahedra. There are two inequivalent B sites. In the first B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Ta(2), five equivalent Ta(1), and two equivalent B(1) atoms. In the second B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Ta(1), four equivalent Ta(2), one B(1), and two equivalent B(2) atoms.
Ta3B4 crystallizes in the orthorhombic Immm space group. There are two inequivalent Ta sites. In the first Ta site, Ta(1) is bonded in a 7-coordinate geometry to two equivalent B(1) and five equivalent B(2) atoms. Both Ta(1)-B(1) bond lengths are 2.36 Å. There are four shorter (2.38 Å) and one longer (2.54 Å) Ta(1)-B(2) bond length. In the second Ta site, Ta(2) is bonded to four equivalent B(2) and eight equivalent B(1) atoms to form a mixture of face and edge-sharing TaB12 cuboctahedra. All Ta(2)-B(2) bond lengths are 2.50 Å. All Ta(2)-B(1) bond lengths are 2.45 Å. There are two inequivalent B sites. In the first B site, B(2) is bonded in a 9-coordinate geometry to two equivalent Ta(2), five equivalent Ta(1), and two equivalent B(1) atoms. Both B(2)-B(1) bond lengths are 1.84 Å. In the second B site, B(1) is bonded in a 9-coordinate geometry to two equivalent Ta(1), four equivalent Ta(2), one B(1), and two equivalent B(2) atoms. The B(1)-B(1) bond length is 1.81 Å.