TaMo3B2C2 crystallizes in the orthorhombic Amm2 space group. Ta(1) is bonded to one B(1), one C(1), and four equivalent C(2) atoms to form distorted TaBC5 square pyramids that share corners with four equivalent Ta(1)BC5 square pyramids, edges with four equivalent Ta(1)BC5 square pyramids, and edges with four equivalent Mo(1)BC5 square pyramids. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one B(2), one C(2), and four equivalent C(1) atoms to form distorted MoBC5 square pyramids that share corners with four equivalent Mo(1)BC5 square pyramids, edges with four equivalent Ta(1)BC5 square pyramids, and edges with four equivalent Mo(1)BC5 square pyramids. In the second Mo site, Mo(2) is bonded in a 1-coordinate geometry to two equivalent B(1), four equivalent B(2), and one C(1) atom. In the third Mo site, Mo(3) is bonded in a 7-coordinate geometry to two equivalent B(2), four equivalent B(1), and one C(2) atom. There are two inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to one Ta(1), two equivalent Mo(2), four equivalent Mo(3), and two equivalent B(2) atoms. In the second B site, B(2) is bonded in a 9-coordinate geometry to one Mo(1), two equivalent Mo(3), four equivalent Mo(2), and two equivalent B(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Ta(1), one Mo(2), and four equivalent Mo(1) atoms to form CTaMo5 octahedra that share corners with four equivalent C(1)TaMo5 octahedra, edges with four equivalent C(2)Ta4Mo2 octahedra, and edges with four equivalent C(1)TaMo5 octahedra. The corner-sharing octahedral tilt angles are 6°. In the second C site, C(2) is bonded to four equivalent Ta(1), one Mo(1), and one Mo(3) atom to form CTa4Mo2 octahedra that share corners with four equivalent C(2)Ta4Mo2 octahedra, edges with four equivalent C(2)Ta4Mo2 octahedra, and edges with four equivalent C(1)TaMo5 octahedra. The corner-sharing octahedral tilt angles are 7°.
TaMo3B2C2 crystallizes in the orthorhombic Amm2 space group. Ta(1) is bonded to one B(1), one C(1), and four equivalent C(2) atoms to form distorted TaBC5 square pyramids that share corners with four equivalent Ta(1)BC5 square pyramids, edges with four equivalent Ta(1)BC5 square pyramids, and edges with four equivalent Mo(1)BC5 square pyramids. The Ta(1)-B(1) bond length is 2.74 Å. The Ta(1)-C(1) bond length is 2.20 Å. All Ta(1)-C(2) bond lengths are 2.21 Å. There are three inequivalent Mo sites. In the first Mo site, Mo(1) is bonded to one B(2), one C(2), and four equivalent C(1) atoms to form distorted MoBC5 square pyramids that share corners with four equivalent Mo(1)BC5 square pyramids, edges with four equivalent Ta(1)BC5 square pyramids, and edges with four equivalent Mo(1)BC5 square pyramids. The Mo(1)-B(2) bond length is 2.73 Å. The Mo(1)-C(2) bond length is 2.19 Å. All Mo(1)-C(1) bond lengths are 2.21 Å. In the second Mo site, Mo(2) is bonded in a 1-coordinate geometry to two equivalent B(1), four equivalent B(2), and one C(1) atom. Both Mo(2)-B(1) bond lengths are 2.37 Å. All Mo(2)-B(2) bond lengths are 2.34 Å. The Mo(2)-C(1) bond length is 2.08 Å. In the third Mo site, Mo(3) is bonded in a 7-coordinate geometry to two equivalent B(2), four equivalent B(1), and one C(2) atom. Both Mo(3)-B(2) bond lengths are 2.32 Å. All Mo(3)-B(1) bond lengths are 2.32 Å. The Mo(3)-C(2) bond length is 2.16 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded in a 9-coordinate geometry to one Ta(1), two equivalent Mo(2), four equivalent Mo(3), and two equivalent B(2) atoms. Both B(1)-B(2) bond lengths are 1.85 Å. In the second B site, B(2) is bonded in a 9-coordinate geometry to one Mo(1), two equivalent Mo(3), four equivalent Mo(2), and two equivalent B(1) atoms. There are two inequivalent C sites. In the first C site, C(1) is bonded to one Ta(1), one Mo(2), and four equivalent Mo(1) atoms to form CTaMo5 octahedra that share corners with four equivalent C(1)TaMo5 octahedra, edges with four equivalent C(2)Ta4Mo2 octahedra, and edges with four equivalent C(1)TaMo5 octahedra. The corner-sharing octahedral tilt angles are 6°. In the second C site, C(2) is bonded to four equivalent Ta(1), one Mo(1), and one Mo(3) atom to form CTa4Mo2 octahedra that share corners with four equivalent C(2)Ta4Mo2 octahedra, edges with four equivalent C(2)Ta4Mo2 octahedra, and edges with four equivalent C(1)TaMo5 octahedra. The corner-sharing octahedral tilt angles are 7°.