BC5 crystallizes in the orthorhombic Imm2 space group. B(1) is bonded to two equivalent C(1) and two equivalent C(3) atoms to form BC4 tetrahedra that share corners with two equivalent B(1)C4 tetrahedra and corners with ten equivalent C(2)C4 tetrahedra. There are three inequivalent C sites. In the first C site, C(1) is bonded to one B(1) and three equivalent C(2) atoms to form distorted CBC3 tetrahedra that share corners with five equivalent C(3)B2C2 tetrahedra and corners with seven equivalent C(1)BC3 tetrahedra. In the second C site, C(2) is bonded to one C(3) and three equivalent C(1) atoms to form CC4 tetrahedra that share corners with five equivalent B(1)C4 tetrahedra and corners with seven equivalent C(2)C4 tetrahedra. In the third C site, C(3) is bonded to two equivalent B(1) and two equivalent C(2) atoms to form distorted CB2C2 tetrahedra that share corners with two equivalent C(3)B2C2 tetrahedra and corners with ten equivalent C(1)BC3 tetrahedra.
BC5 crystallizes in the orthorhombic Imm2 space group. B(1) is bonded to two equivalent C(1) and two equivalent C(3) atoms to form BC4 tetrahedra that share corners with two equivalent B(1)C4 tetrahedra and corners with ten equivalent C(2)C4 tetrahedra. Both B(1)-C(1) bond lengths are 1.61 Å. Both B(1)-C(3) bond lengths are 1.68 Å. There are three inequivalent C sites. In the first C site, C(1) is bonded to one B(1) and three equivalent C(2) atoms to form distorted CBC3 tetrahedra that share corners with five equivalent C(3)B2C2 tetrahedra and corners with seven equivalent C(1)BC3 tetrahedra. There are two shorter (1.54 Å) and one longer (1.56 Å) C(1)-C(2) bond length. In the second C site, C(2) is bonded to one C(3) and three equivalent C(1) atoms to form CC4 tetrahedra that share corners with five equivalent B(1)C4 tetrahedra and corners with seven equivalent C(2)C4 tetrahedra. The C(2)-C(3) bond length is 1.53 Å. In the third C site, C(3) is bonded to two equivalent B(1) and two equivalent C(2) atoms to form distorted CB2C2 tetrahedra that share corners with two equivalent C(3)B2C2 tetrahedra and corners with ten equivalent C(1)BC3 tetrahedra.