MgEu(ReO4)2 crystallizes in the trigonal P-3m1 space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Re(1)O4 tetrahedra. Eu(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. Re(1) is bonded to one O(2) and three equivalent O(1) atoms to form ReO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Eu(1), and one Re(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Re(1) atom.
MgEu(ReO4)2 crystallizes in the trigonal P-3m1 space group. Mg(1) is bonded to six equivalent O(1) atoms to form MgO6 octahedra that share corners with six equivalent Re(1)O4 tetrahedra. All Mg(1)-O(1) bond lengths are 2.18 Å. Eu(1) is bonded in a 6-coordinate geometry to six equivalent O(1) atoms. All Eu(1)-O(1) bond lengths are 2.45 Å. Re(1) is bonded to one O(2) and three equivalent O(1) atoms to form ReO4 tetrahedra that share corners with three equivalent Mg(1)O6 octahedra. The corner-sharing octahedral tilt angles are 55°. The Re(1)-O(2) bond length is 1.75 Å. All Re(1)-O(1) bond lengths are 1.84 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to one Mg(1), one Eu(1), and one Re(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to one Re(1) atom.