NaTl3Cu4Te2O12 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and edges with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles are 5°. Cu(1) is bonded in a 4-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a distorted bent 150 degrees geometry to two equivalent O(1) atoms. In the second Tl site, Tl(2) is bonded in a linear geometry to two equivalent O(3) atoms. Te(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TeO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra and  an edgeedge with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 5°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Cu(1), one Tl(1), and one Te(1) atom. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to two equivalent Cu(1) and one Te(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Cu(1), one Tl(2), and one Te(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1) and one Te(1) atom.
NaTl3Cu4Te2O12 crystallizes in the monoclinic C2/m space group. Na(1) is bonded to two equivalent O(4) and four equivalent O(1) atoms to form NaO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and edges with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles are 5°. Both Na(1)-O(4) bond lengths are 2.40 Å. All Na(1)-O(1) bond lengths are 2.51 Å. Cu(1) is bonded in a 4-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Cu(1)-O(3) bond length is 1.99 Å. There is one shorter (1.98 Å) and one longer (2.65 Å) Cu(1)-O(1) bond length. There is one shorter (2.01 Å) and one longer (2.05 Å) Cu(1)-O(2) bond length. There are two inequivalent Tl sites. In the first Tl site, Tl(1) is bonded in a distorted bent 150 degrees geometry to two equivalent O(1) atoms. Both Tl(1)-O(1) bond lengths are 2.64 Å. In the second Tl site, Tl(2) is bonded in a linear geometry to two equivalent O(3) atoms. Both Tl(2)-O(3) bond lengths are 2.82 Å. Te(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form TeO6 octahedra that share  a cornercorner with one Na(1)O6 octahedra and  an edgeedge with one Na(1)O6 octahedra. The corner-sharing octahedral tilt angles are 5°. The Te(1)-O(3) bond length is 2.03 Å. The Te(1)-O(4) bond length is 1.91 Å. Both Te(1)-O(1) bond lengths are 1.96 Å. Both Te(1)-O(2) bond lengths are 2.01 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Na(1), two equivalent Cu(1), one Tl(1), and one Te(1) atom. In the second O site, O(2) is bonded in a trigonal non-coplanar geometry to two equivalent Cu(1) and one Te(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to two equivalent Cu(1), one Tl(2), and one Te(1) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Na(1) and one Te(1) atom.