Ba2EuCu2HgO7 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 9-coordinate geometry to one O(3), four equivalent O(1), and four equivalent O(2) atoms. Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. Cu(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted corner-sharing CuO5 square pyramids. Hg(1) is bonded in a linear geometry to two equivalent O(1) atoms. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1), one Cu(1), and one Hg(1) atom to form a mixture of distorted edge and corner-sharing OBa4CuHg octahedra. The corner-sharing octahedral tilt angles range from 0-20°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Eu(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1) atoms.
Ba2EuCu2HgO7 crystallizes in the tetragonal P4/mmm space group. Ba(1) is bonded in a 9-coordinate geometry to one O(3), four equivalent O(1), and four equivalent O(2) atoms. The Ba(1)-O(3) bond length is 2.59 Å. All Ba(1)-O(1) bond lengths are 2.78 Å. All Ba(1)-O(2) bond lengths are 3.04 Å. Eu(1) is bonded in a body-centered cubic geometry to eight equivalent O(2) atoms. All Eu(1)-O(2) bond lengths are 2.46 Å. Cu(1) is bonded to one O(1) and four equivalent O(2) atoms to form distorted corner-sharing CuO5 square pyramids. The Cu(1)-O(1) bond length is 2.59 Å. All Cu(1)-O(2) bond lengths are 1.95 Å. Hg(1) is bonded in a linear geometry to two equivalent O(1) atoms. Both Hg(1)-O(1) bond lengths are 2.11 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded to four equivalent Ba(1), one Cu(1), and one Hg(1) atom to form a mixture of distorted edge and corner-sharing OBa4CuHg octahedra. The corner-sharing octahedral tilt angles range from 0-20°. In the second O site, O(2) is bonded in a 6-coordinate geometry to two equivalent Ba(1), two equivalent Eu(1), and two equivalent Cu(1) atoms. In the third O site, O(3) is bonded in a distorted linear geometry to two equivalent Ba(1) atoms.