Mg2TeSe is Enargite-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Te(1) and three equivalent Se(1) atoms to form MgTeSe3 tetrahedra that share corners with six equivalent Mg(2)Te3Se tetrahedra and corners with six equivalent Mg(1)TeSe3 tetrahedra. In the second Mg site, Mg(2) is bonded to three equivalent Te(1) and one Se(1) atom to form MgTe3Se tetrahedra that share corners with six equivalent Mg(2)Te3Se tetrahedra and corners with six equivalent Mg(1)TeSe3 tetrahedra. Te(1) is bonded to one Mg(1) and three equivalent Mg(2) atoms to form TeMg4 tetrahedra that share corners with six equivalent Te(1)Mg4 tetrahedra and corners with six equivalent Se(1)Mg4 tetrahedra. Se(1) is bonded to one Mg(2) and three equivalent Mg(1) atoms to form SeMg4 tetrahedra that share corners with six equivalent Te(1)Mg4 tetrahedra and corners with six equivalent Se(1)Mg4 tetrahedra.
Mg2TeSe is Enargite-like structured and crystallizes in the trigonal R3m space group. There are two inequivalent Mg sites. In the first Mg site, Mg(1) is bonded to one Te(1) and three equivalent Se(1) atoms to form MgTeSe3 tetrahedra that share corners with six equivalent Mg(2)Te3Se tetrahedra and corners with six equivalent Mg(1)TeSe3 tetrahedra. The Mg(1)-Te(1) bond length is 2.80 Å. All Mg(1)-Se(1) bond lengths are 2.67 Å. In the second Mg site, Mg(2) is bonded to three equivalent Te(1) and one Se(1) atom to form MgTe3Se tetrahedra that share corners with six equivalent Mg(2)Te3Se tetrahedra and corners with six equivalent Mg(1)TeSe3 tetrahedra. All Mg(2)-Te(1) bond lengths are 2.77 Å. The Mg(2)-Se(1) bond length is 2.60 Å. Te(1) is bonded to one Mg(1) and three equivalent Mg(2) atoms to form TeMg4 tetrahedra that share corners with six equivalent Te(1)Mg4 tetrahedra and corners with six equivalent Se(1)Mg4 tetrahedra. Se(1) is bonded to one Mg(2) and three equivalent Mg(1) atoms to form SeMg4 tetrahedra that share corners with six equivalent Te(1)Mg4 tetrahedra and corners with six equivalent Se(1)Mg4 tetrahedra.