Tb2B2C3 crystallizes in the orthorhombic Cmmm space group. Tb(1) is bonded in a 10-coordinate geometry to six equivalent B(1) and four equivalent C(1) atoms. B(1) is bonded in a single-bond geometry to six equivalent Tb(1) and one C(1) atom. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to four equivalent Tb(1), one B(1), and one C(2) atom. In the second C site, C(2) is bonded in a linear geometry to two equivalent C(1) atoms.
Tb2B2C3 crystallizes in the orthorhombic Cmmm space group. Tb(1) is bonded in a 10-coordinate geometry to six equivalent B(1) and four equivalent C(1) atoms. There are two shorter (2.68 Å) and four longer (2.73 Å) Tb(1)-B(1) bond lengths. All Tb(1)-C(1) bond lengths are 2.56 Å. B(1) is bonded in a single-bond geometry to six equivalent Tb(1) and one C(1) atom. The B(1)-C(1) bond length is 1.54 Å. There are two inequivalent C sites. In the first C site, C(1) is bonded in a distorted single-bond geometry to four equivalent Tb(1), one B(1), and one C(2) atom. The C(1)-C(2) bond length is 1.34 Å. In the second C site, C(2) is bonded in a linear geometry to two equivalent C(1) atoms.