Tm2Cu(B2O5)2 is Esseneite-like structured and crystallizes in the monoclinic P2_1/c space group. Tm(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. Cu(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted CuO6 octahedra that share corners with two equivalent B(2)O4 tetrahedra, corners with four equivalent B(1)O4 tetrahedra, and edges with two equivalent B(2)O4 tetrahedra. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form BO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with three equivalent B(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 67-71°. In the second B site, B(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form BO4 tetrahedra that share  a cornercorner with one Cu(1)O6 octahedra, corners with three equivalent B(1)O4 tetrahedra, and  an edgeedge with one Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Tm(1), one B(1), and one B(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one B(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Tm(1), one Cu(1), and one B(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Tm(1), one Cu(1), one B(1), and one B(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Tm(1), one Cu(1), one B(1), and one B(2) atom.
Tm2Cu(B2O5)2 is Esseneite-like structured and crystallizes in the monoclinic P2_1/c space group. Tm(1) is bonded in a 8-coordinate geometry to one O(4), one O(5), two equivalent O(1), two equivalent O(2), and two equivalent O(3) atoms. The Tm(1)-O(4) bond length is 2.37 Å. The Tm(1)-O(5) bond length is 2.32 Å. There is one shorter (2.51 Å) and one longer (2.62 Å) Tm(1)-O(1) bond length. Both Tm(1)-O(2) bond lengths are 2.19 Å. There is one shorter (2.31 Å) and one longer (2.43 Å) Tm(1)-O(3) bond length. Cu(1) is bonded to two equivalent O(3), two equivalent O(4), and two equivalent O(5) atoms to form distorted CuO6 octahedra that share corners with two equivalent B(2)O4 tetrahedra, corners with four equivalent B(1)O4 tetrahedra, and edges with two equivalent B(2)O4 tetrahedra. Both Cu(1)-O(3) bond lengths are 1.96 Å. Both Cu(1)-O(4) bond lengths are 2.06 Å. Both Cu(1)-O(5) bond lengths are 2.35 Å. There are two inequivalent B sites. In the first B site, B(1) is bonded to one O(1), one O(2), one O(4), and one O(5) atom to form BO4 tetrahedra that share corners with two equivalent Cu(1)O6 octahedra and corners with three equivalent B(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 67-71°. The B(1)-O(1) bond length is 1.51 Å. The B(1)-O(2) bond length is 1.42 Å. The B(1)-O(4) bond length is 1.55 Å. The B(1)-O(5) bond length is 1.50 Å. In the second B site, B(2) is bonded to one O(1), one O(3), one O(4), and one O(5) atom to form BO4 tetrahedra that share  a cornercorner with one Cu(1)O6 octahedra, corners with three equivalent B(1)O4 tetrahedra, and  an edgeedge with one Cu(1)O6 octahedra. The corner-sharing octahedral tilt angles are 60°. The B(2)-O(1) bond length is 1.50 Å. The B(2)-O(3) bond length is 1.44 Å. The B(2)-O(4) bond length is 1.53 Å. The B(2)-O(5) bond length is 1.49 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to two equivalent Tm(1), one B(1), and one B(2) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Tm(1) and one B(1) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Tm(1), one Cu(1), and one B(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Tm(1), one Cu(1), one B(1), and one B(2) atom. In the fifth O site, O(5) is bonded in a distorted bent 120 degrees geometry to one Tm(1), one Cu(1), one B(1), and one B(2) atom.