Cu2SnSe3 is Enargite-like structured and crystallizes in the orthorhombic Imm2 space group. Cu(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with five equivalent Sn(1)Se4 tetrahedra and corners with seven equivalent Cu(1)Se4 tetrahedra. Sn(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form SnSe4 tetrahedra that share corners with two equivalent Sn(1)Se4 tetrahedra and corners with ten equivalent Cu(1)Se4 tetrahedra. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to two equivalent Cu(1) and two equivalent Sn(1) atoms to form SeCu2Sn2 tetrahedra that share corners with two equivalent Se(2)Cu2Sn2 tetrahedra and corners with ten equivalent Se(1)Cu3Sn tetrahedra. In the second Se site, Se(1) is bonded to three equivalent Cu(1) and one Sn(1) atom to form SeCu3Sn tetrahedra that share corners with five equivalent Se(2)Cu2Sn2 tetrahedra and corners with seven equivalent Se(1)Cu3Sn tetrahedra.
Cu2SnSe3 is Enargite-like structured and crystallizes in the orthorhombic Imm2 space group. Cu(1) is bonded to one Se(2) and three equivalent Se(1) atoms to form CuSe4 tetrahedra that share corners with five equivalent Sn(1)Se4 tetrahedra and corners with seven equivalent Cu(1)Se4 tetrahedra. The Cu(1)-Se(2) bond length is 2.45 Å. All Cu(1)-Se(1) bond lengths are 2.44 Å. Sn(1) is bonded to two equivalent Se(1) and two equivalent Se(2) atoms to form SnSe4 tetrahedra that share corners with two equivalent Sn(1)Se4 tetrahedra and corners with ten equivalent Cu(1)Se4 tetrahedra. Both Sn(1)-Se(1) bond lengths are 2.61 Å. Both Sn(1)-Se(2) bond lengths are 2.69 Å. There are two inequivalent Se sites. In the first Se site, Se(2) is bonded to two equivalent Cu(1) and two equivalent Sn(1) atoms to form SeCu2Sn2 tetrahedra that share corners with two equivalent Se(2)Cu2Sn2 tetrahedra and corners with ten equivalent Se(1)Cu3Sn tetrahedra. In the second Se site, Se(1) is bonded to three equivalent Cu(1) and one Sn(1) atom to form SeCu3Sn tetrahedra that share corners with five equivalent Se(2)Cu2Sn2 tetrahedra and corners with seven equivalent Se(1)Cu3Sn tetrahedra.