Tm(FeB)2 crystallizes in the tetragonal I4/mmm space group. Tm(1) is bonded in a 16-coordinate geometry to eight equivalent Fe(1) and eight equivalent B(1) atoms. Fe(1) is bonded to four equivalent Tm(1) and four equivalent B(1) atoms to form a mixture of distorted corner, edge, and face-sharing FeTm4B4 tetrahedra. B(1) is bonded in a 9-coordinate geometry to four equivalent Tm(1), four equivalent Fe(1), and one B(1) atom.
Tm(FeB)2 crystallizes in the tetragonal I4/mmm space group. Tm(1) is bonded in a 16-coordinate geometry to eight equivalent Fe(1) and eight equivalent B(1) atoms. All Tm(1)-Fe(1) bond lengths are 2.91 Å. All Tm(1)-B(1) bond lengths are 2.65 Å. Fe(1) is bonded to four equivalent Tm(1) and four equivalent B(1) atoms to form a mixture of distorted corner, edge, and face-sharing FeTm4B4 tetrahedra. All Fe(1)-B(1) bond lengths are 2.17 Å. B(1) is bonded in a 9-coordinate geometry to four equivalent Tm(1), four equivalent Fe(1), and one B(1) atom. The B(1)-B(1) bond length is 2.06 Å.