Cu4BiSe4I is Chalcostibite-derived structured and crystallizes in the orthorhombic Pnma space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(4), and two equivalent I(1) atoms to form CuSe2I2 tetrahedra that share corners with two equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with two equivalent Cu(2)Se3I tetrahedra, and corners with two equivalent Cu(4)Se4 tetrahedra. In the second Cu site, Cu(2) is bonded to three equivalent Se(3) and one I(1) atom to form distorted CuSe3I tetrahedra that share corners with four equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with two equivalent Cu(2)Se3I tetrahedra,  an edgeedge with one Bi(1)Se5 square pyramid, and edges with two equivalent Cu(2)Se3I tetrahedra. In the third Cu site, Cu(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Se(2) and two equivalent Se(4) atoms. In the fourth Cu site, Cu(4) is bonded to one Se(1), one Se(4), and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, and corners with two equivalent Cu(4)Se4 tetrahedra. Bi(1) is bonded to one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with four equivalent Cu(2)Se3I tetrahedra, corners with four equivalent Cu(4)Se4 tetrahedra, edges with two equivalent Bi(1)Se5 square pyramids, and  an edgeedge with one Cu(2)Se3I tetrahedra. There are four inequivalent Se sites. In the first Se site, Se(4) is bonded in a 5-coordinate geometry to one Cu(1), one Cu(4), two equivalent Cu(3), and one Se(3) atom. In the second Se site, Se(1) is bonded to one Cu(1), one Cu(4), and two equivalent Bi(1) atoms to form corner-sharing SeCu2Bi2 tetrahedra. In the third Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent Cu(3), two equivalent Cu(4), and one Bi(1) atom. In the fourth Se site, Se(3) is bonded in a 6-coordinate geometry to three equivalent Cu(2), two equivalent Bi(1), and one Se(4) atom. I(1) is bonded in a distorted trigonal non-coplanar geometry to one Cu(2) and two equivalent Cu(1) atoms.
Cu4BiSe4I is Chalcostibite-derived structured and crystallizes in the orthorhombic Pnma space group. There are four inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one Se(1), one Se(4), and two equivalent I(1) atoms to form CuSe2I2 tetrahedra that share corners with two equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with two equivalent Cu(2)Se3I tetrahedra, and corners with two equivalent Cu(4)Se4 tetrahedra. The Cu(1)-Se(1) bond length is 2.36 Å. The Cu(1)-Se(4) bond length is 2.50 Å. Both Cu(1)-I(1) bond lengths are 2.65 Å. In the second Cu site, Cu(2) is bonded to three equivalent Se(3) and one I(1) atom to form distorted CuSe3I tetrahedra that share corners with four equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with two equivalent Cu(2)Se3I tetrahedra,  an edgeedge with one Bi(1)Se5 square pyramid, and edges with two equivalent Cu(2)Se3I tetrahedra. There are two shorter (2.48 Å) and one longer (2.53 Å) Cu(2)-Se(3) bond length. The Cu(2)-I(1) bond length is 2.71 Å. In the third Cu site, Cu(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Se(2) and two equivalent Se(4) atoms. There is one shorter (2.43 Å) and one longer (3.03 Å) Cu(3)-Se(2) bond length. Both Cu(3)-Se(4) bond lengths are 2.38 Å. In the fourth Cu site, Cu(4) is bonded to one Se(1), one Se(4), and two equivalent Se(2) atoms to form distorted CuSe4 tetrahedra that share corners with four equivalent Bi(1)Se5 square pyramids, corners with two equivalent Cu(1)Se2I2 tetrahedra, and corners with two equivalent Cu(4)Se4 tetrahedra. The Cu(4)-Se(1) bond length is 2.46 Å. The Cu(4)-Se(4) bond length is 2.55 Å. Both Cu(4)-Se(2) bond lengths are 2.47 Å. Bi(1) is bonded to one Se(2), two equivalent Se(1), and two equivalent Se(3) atoms to form distorted BiSe5 square pyramids that share corners with two equivalent Cu(1)Se2I2 tetrahedra, corners with four equivalent Cu(2)Se3I tetrahedra, corners with four equivalent Cu(4)Se4 tetrahedra, edges with two equivalent Bi(1)Se5 square pyramids, and  an edgeedge with one Cu(2)Se3I tetrahedra. The Bi(1)-Se(2) bond length is 2.73 Å. Both Bi(1)-Se(1) bond lengths are 2.83 Å. Both Bi(1)-Se(3) bond lengths are 3.31 Å. There are four inequivalent Se sites. In the first Se site, Se(4) is bonded in a 5-coordinate geometry to one Cu(1), one Cu(4), two equivalent Cu(3), and one Se(3) atom. The Se(4)-Se(3) bond length is 2.52 Å. In the second Se site, Se(1) is bonded to one Cu(1), one Cu(4), and two equivalent Bi(1) atoms to form corner-sharing SeCu2Bi2 tetrahedra. In the third Se site, Se(2) is bonded in a 5-coordinate geometry to two equivalent Cu(3), two equivalent Cu(4), and one Bi(1) atom. In the fourth Se site, Se(3) is bonded in a 6-coordinate geometry to three equivalent Cu(2), two equivalent Bi(1), and one Se(4) atom. I(1) is bonded in a distorted trigonal non-coplanar geometry to one Cu(2) and two equivalent Cu(1) atoms.