MgCoCu2SnS4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one Sn(1), one S(2), one S(3), and two equivalent S(1) atoms to form distorted MgSnS4 tetrahedra that share corners with two equivalent Co(1)S4 tetrahedra, corners with two equivalent S(1)MgCoCu2Sn trigonal bipyramids,  an edgeedge with one Co(1)S4 tetrahedra, and edges with four equivalent Cu(1)S4 tetrahedra. Co(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form CoS4 tetrahedra that share corners with two equivalent Mg(1)SnS4 tetrahedra, corners with eight equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Mg(1)SnS4 tetrahedra. Cu(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CuS4 tetrahedra that share corners with four equivalent Co(1)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and edges with two equivalent Mg(1)SnS4 tetrahedra. Sn(1) is bonded in a 5-coordinate geometry to one Mg(1), one S(2), one S(3), and two equivalent S(1) atoms. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom to form distorted SMgCoCu2Sn trigonal bipyramids that share  a cornercorner with one Mg(1)SnS4 tetrahedra, corners with three equivalent S(1)MgCoCu2Sn trigonal bipyramids, and  an edgeedge with one S(1)MgCoCu2Sn trigonal bipyramid. In the second S site, S(2) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom.
MgCoCu2SnS4 crystallizes in the monoclinic Cm space group. Mg(1) is bonded to one Sn(1), one S(2), one S(3), and two equivalent S(1) atoms to form distorted MgSnS4 tetrahedra that share corners with two equivalent Co(1)S4 tetrahedra, corners with two equivalent S(1)MgCoCu2Sn trigonal bipyramids,  an edgeedge with one Co(1)S4 tetrahedra, and edges with four equivalent Cu(1)S4 tetrahedra. The Mg(1)-Sn(1) bond length is 3.17 Å. The Mg(1)-S(2) bond length is 2.37 Å. The Mg(1)-S(3) bond length is 2.37 Å. Both Mg(1)-S(1) bond lengths are 2.38 Å. Co(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form CoS4 tetrahedra that share corners with two equivalent Mg(1)SnS4 tetrahedra, corners with eight equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Mg(1)SnS4 tetrahedra. The Co(1)-S(2) bond length is 2.25 Å. The Co(1)-S(3) bond length is 2.25 Å. Both Co(1)-S(1) bond lengths are 2.28 Å. Cu(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form distorted CuS4 tetrahedra that share corners with four equivalent Co(1)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and edges with two equivalent Mg(1)SnS4 tetrahedra. The Cu(1)-S(2) bond length is 2.59 Å. The Cu(1)-S(3) bond length is 2.60 Å. Both Cu(1)-S(1) bond lengths are 2.36 Å. Sn(1) is bonded in a 5-coordinate geometry to one Mg(1), one S(2), one S(3), and two equivalent S(1) atoms. The Sn(1)-S(2) bond length is 2.89 Å. The Sn(1)-S(3) bond length is 2.89 Å. Both Sn(1)-S(1) bond lengths are 2.70 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom to form distorted SMgCoCu2Sn trigonal bipyramids that share  a cornercorner with one Mg(1)SnS4 tetrahedra, corners with three equivalent S(1)MgCoCu2Sn trigonal bipyramids, and  an edgeedge with one S(1)MgCoCu2Sn trigonal bipyramid. In the second S site, S(2) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom. In the third S site, S(3) is bonded in a 5-coordinate geometry to one Mg(1), one Co(1), two equivalent Cu(1), and one Sn(1) atom.