Fe9Cu9S16 crystallizes in the tetragonal P-42m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent S(1) and two equivalent S(3) atoms to form FeS4 tetrahedra that share corners with two equivalent Fe(1)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with two equivalent Cu(2)S4 tetrahedra, corners with two equivalent Cu(3)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Fe(5)S4 tetrahedra. In the second Fe site, Fe(2) is bonded to four equivalent S(1) atoms to form FeS4 tetrahedra that share corners with four equivalent Fe(1)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and corners with four equivalent Cu(2)S4 tetrahedra. In the third Fe site, Fe(3) is bonded to four equivalent S(2) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, corners with eight equivalent Cu(2)S4 tetrahedra, and edges with two equivalent Fe(4)S4 tetrahedra. In the fourth Fe site, Fe(4) is bonded to four equivalent S(2) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, edges with two equivalent Fe(3)S4 tetrahedra, and edges with four equivalent Cu(2)S4 tetrahedra. In the fifth Fe site, Fe(5) is bonded to four equivalent S(3) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, edges with two equivalent Cu(3)S4 tetrahedra, and edges with four equivalent Fe(1)S4 tetrahedra. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form CuS4 tetrahedra that share  a cornercorner with one Fe(3)S4 tetrahedra,  a cornercorner with one Fe(4)S4 tetrahedra,  a cornercorner with one Fe(5)S4 tetrahedra,  a cornercorner with one Cu(3)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with four equivalent Fe(1)S4 tetrahedra, and corners with four equivalent Cu(2)S4 tetrahedra. In the second Cu site, Cu(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with two equivalent Fe(1)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with two equivalent Fe(3)S4 tetrahedra, corners with two equivalent Cu(2)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Fe(4)S4 tetrahedra. In the third Cu site, Cu(3) is bonded to four equivalent S(3) atoms to form CuS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, corners with eight equivalent Fe(1)S4 tetrahedra, and edges with two equivalent Fe(5)S4 tetrahedra. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), one Fe(2), one Cu(1), and one Cu(2) atom to form SFe2Cu2 tetrahedra that share corners with six equivalent S(1)Fe2Cu2 tetrahedra, corners with three equivalent S(2)Fe2Cu3 trigonal bipyramids, and corners with three equivalent S(3)Fe3Cu2 trigonal bipyramids. In the second S site, S(2) is bonded to one Fe(3), one Fe(4), one Cu(1), and two equivalent Cu(2) atoms to form distorted SFe2Cu3 trigonal bipyramids that share corners with six equivalent S(1)Fe2Cu2 tetrahedra,  a cornercorner with one S(3)Fe3Cu2 trigonal bipyramid, corners with two equivalent S(2)Fe2Cu3 trigonal bipyramids, and edges with three equivalent S(2)Fe2Cu3 trigonal bipyramids. In the third S site, S(3) is bonded to one Fe(5), two equivalent Fe(1), one Cu(1), and one Cu(3) atom to form distorted SFe3Cu2 trigonal bipyramids that share corners with six equivalent S(1)Fe2Cu2 tetrahedra,  a cornercorner with one S(2)Fe2Cu3 trigonal bipyramid, corners with two equivalent S(3)Fe3Cu2 trigonal bipyramids, and edges with three equivalent S(3)Fe3Cu2 trigonal bipyramids.
Fe9Cu9S16 crystallizes in the tetragonal P-42m space group. There are five inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to two equivalent S(1) and two equivalent S(3) atoms to form FeS4 tetrahedra that share corners with two equivalent Fe(1)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with two equivalent Cu(2)S4 tetrahedra, corners with two equivalent Cu(3)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Fe(5)S4 tetrahedra. Both Fe(1)-S(1) bond lengths are 2.27 Å. Both Fe(1)-S(3) bond lengths are 2.26 Å. In the second Fe site, Fe(2) is bonded to four equivalent S(1) atoms to form FeS4 tetrahedra that share corners with four equivalent Fe(1)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and corners with four equivalent Cu(2)S4 tetrahedra. All Fe(2)-S(1) bond lengths are 2.27 Å. In the third Fe site, Fe(3) is bonded to four equivalent S(2) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, corners with eight equivalent Cu(2)S4 tetrahedra, and edges with two equivalent Fe(4)S4 tetrahedra. All Fe(3)-S(2) bond lengths are 2.16 Å. In the fourth Fe site, Fe(4) is bonded to four equivalent S(2) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, edges with two equivalent Fe(3)S4 tetrahedra, and edges with four equivalent Cu(2)S4 tetrahedra. All Fe(4)-S(2) bond lengths are 2.21 Å. In the fifth Fe site, Fe(5) is bonded to four equivalent S(3) atoms to form FeS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, edges with two equivalent Cu(3)S4 tetrahedra, and edges with four equivalent Fe(1)S4 tetrahedra. All Fe(5)-S(3) bond lengths are 2.25 Å. There are three inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one S(2), one S(3), and two equivalent S(1) atoms to form CuS4 tetrahedra that share  a cornercorner with one Fe(3)S4 tetrahedra,  a cornercorner with one Fe(4)S4 tetrahedra,  a cornercorner with one Fe(5)S4 tetrahedra,  a cornercorner with one Cu(3)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with four equivalent Fe(1)S4 tetrahedra, and corners with four equivalent Cu(2)S4 tetrahedra. The Cu(1)-S(2) bond length is 2.36 Å. The Cu(1)-S(3) bond length is 2.37 Å. Both Cu(1)-S(1) bond lengths are 2.24 Å. In the second Cu site, Cu(2) is bonded to two equivalent S(1) and two equivalent S(2) atoms to form CuS4 tetrahedra that share corners with two equivalent Fe(1)S4 tetrahedra, corners with two equivalent Fe(2)S4 tetrahedra, corners with two equivalent Fe(3)S4 tetrahedra, corners with two equivalent Cu(2)S4 tetrahedra, corners with four equivalent Cu(1)S4 tetrahedra, and  an edgeedge with one Fe(4)S4 tetrahedra. Both Cu(2)-S(1) bond lengths are 2.27 Å. Both Cu(2)-S(2) bond lengths are 2.32 Å. In the third Cu site, Cu(3) is bonded to four equivalent S(3) atoms to form CuS4 tetrahedra that share corners with four equivalent Cu(1)S4 tetrahedra, corners with eight equivalent Fe(1)S4 tetrahedra, and edges with two equivalent Fe(5)S4 tetrahedra. All Cu(3)-S(3) bond lengths are 2.32 Å. There are three inequivalent S sites. In the first S site, S(1) is bonded to one Fe(1), one Fe(2), one Cu(1), and one Cu(2) atom to form SFe2Cu2 tetrahedra that share corners with six equivalent S(1)Fe2Cu2 tetrahedra, corners with three equivalent S(2)Fe2Cu3 trigonal bipyramids, and corners with three equivalent S(3)Fe3Cu2 trigonal bipyramids. In the second S site, S(2) is bonded to one Fe(3), one Fe(4), one Cu(1), and two equivalent Cu(2) atoms to form distorted SFe2Cu3 trigonal bipyramids that share corners with six equivalent S(1)Fe2Cu2 tetrahedra,  a cornercorner with one S(3)Fe3Cu2 trigonal bipyramid, corners with two equivalent S(2)Fe2Cu3 trigonal bipyramids, and edges with three equivalent S(2)Fe2Cu3 trigonal bipyramids. In the third S site, S(3) is bonded to one Fe(5), two equivalent Fe(1), one Cu(1), and one Cu(3) atom to form distorted SFe3Cu2 trigonal bipyramids that share corners with six equivalent S(1)Fe2Cu2 tetrahedra,  a cornercorner with one S(2)Fe2Cu3 trigonal bipyramid, corners with two equivalent S(3)Fe3Cu2 trigonal bipyramids, and edges with three equivalent S(3)Fe3Cu2 trigonal bipyramids.