K4Cu4OCl10 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(3), one Cl(5), two equivalent Cl(6), and three equivalent Cl(4) atoms. In the second K site, K(2) is bonded in a 8-coordinate geometry to one Cl(2), one Cl(4), two equivalent Cl(1), two equivalent Cl(3), and two equivalent Cl(5) atoms. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one Cl(1), one Cl(2), one Cl(3), and one Cl(5) atom to form distorted edge-sharing CuCl4O trigonal bipyramids. In the second Cu site, Cu(2) is bonded to one O(1), one Cl(3), one Cl(4), one Cl(5), and one Cl(6) atom to form distorted edge-sharing CuCl4O trigonal bipyramids. O(1) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form OCu4 tetrahedra that share  an edgeedge with one Cl(6)K4Cu2 octahedra, edges with two equivalent Cl(3)K3Cu2 trigonal bipyramids, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids. There are six inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Cu(1) atom. In the second Cl site, Cl(2) is bonded in a square co-planar geometry to two equivalent K(2) and two equivalent Cu(1) atoms. In the third Cl site, Cl(3) is bonded to one K(1), two equivalent K(2), one Cu(1), and one Cu(2) atom to form distorted ClK3Cu2 trigonal bipyramids that share corners with three equivalent Cl(6)K4Cu2 octahedra, corners with three equivalent Cl(5)K3Cu2 trigonal bipyramids,  an edgeedge with one O(1)Cu4 tetrahedra,  an edgeedge with one Cl(3)K3Cu2 trigonal bipyramid, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-56°. In the fourth Cl site, Cl(4) is bonded in a 4-coordinate geometry to one K(2), three equivalent K(1), and one Cu(2) atom. In the fifth Cl site, Cl(5) is bonded to one K(1), two equivalent K(2), one Cu(1), and one Cu(2) atom to form distorted ClK3Cu2 trigonal bipyramids that share  a cornercorner with one Cl(6)K4Cu2 octahedra, corners with three equivalent Cl(3)K3Cu2 trigonal bipyramids,  an edgeedge with one Cl(6)K4Cu2 octahedra,  an edgeedge with one O(1)Cu4 tetrahedra,  an edgeedge with one Cl(5)K3Cu2 trigonal bipyramid, and edges with two equivalent Cl(3)K3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. In the sixth Cl site, Cl(6) is bonded to four equivalent K(1) and two equivalent Cu(2) atoms to form distorted ClK4Cu2 octahedra that share corners with two equivalent Cl(5)K3Cu2 trigonal bipyramids, corners with six equivalent Cl(3)K3Cu2 trigonal bipyramids, edges with two equivalent Cl(6)K4Cu2 octahedra,  an edgeedge with one O(1)Cu4 tetrahedra, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids.
K4Cu4OCl10 crystallizes in the monoclinic C2/c space group. There are two inequivalent K sites. In the first K site, K(1) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(3), one Cl(5), two equivalent Cl(6), and three equivalent Cl(4) atoms. The K(1)-Cl(1) bond length is 3.19 Å. The K(1)-Cl(3) bond length is 3.20 Å. The K(1)-Cl(5) bond length is 3.18 Å. There is one shorter (3.38 Å) and one longer (3.49 Å) K(1)-Cl(6) bond length. There are two shorter (3.17 Å) and one longer (3.64 Å) K(1)-Cl(4) bond length. In the second K site, K(2) is bonded in a 8-coordinate geometry to one Cl(2), one Cl(4), two equivalent Cl(1), two equivalent Cl(3), and two equivalent Cl(5) atoms. The K(2)-Cl(2) bond length is 3.23 Å. The K(2)-Cl(4) bond length is 3.17 Å. There is one shorter (3.18 Å) and one longer (3.38 Å) K(2)-Cl(1) bond length. There is one shorter (3.23 Å) and one longer (3.52 Å) K(2)-Cl(3) bond length. There is one shorter (3.07 Å) and one longer (3.48 Å) K(2)-Cl(5) bond length. There are two inequivalent Cu sites. In the first Cu site, Cu(1) is bonded to one O(1), one Cl(1), one Cl(2), one Cl(3), and one Cl(5) atom to form distorted edge-sharing CuCl4O trigonal bipyramids. The Cu(1)-O(1) bond length is 1.93 Å. The Cu(1)-Cl(1) bond length is 2.25 Å. The Cu(1)-Cl(2) bond length is 2.38 Å. The Cu(1)-Cl(3) bond length is 2.50 Å. The Cu(1)-Cl(5) bond length is 2.36 Å. In the second Cu site, Cu(2) is bonded to one O(1), one Cl(3), one Cl(4), one Cl(5), and one Cl(6) atom to form distorted edge-sharing CuCl4O trigonal bipyramids. The Cu(2)-O(1) bond length is 1.92 Å. The Cu(2)-Cl(3) bond length is 2.35 Å. The Cu(2)-Cl(4) bond length is 2.24 Å. The Cu(2)-Cl(5) bond length is 2.43 Å. The Cu(2)-Cl(6) bond length is 2.38 Å. O(1) is bonded to two equivalent Cu(1) and two equivalent Cu(2) atoms to form OCu4 tetrahedra that share  an edgeedge with one Cl(6)K4Cu2 octahedra, edges with two equivalent Cl(3)K3Cu2 trigonal bipyramids, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids. There are six inequivalent Cl sites. In the first Cl site, Cl(1) is bonded in a 4-coordinate geometry to one K(1), two equivalent K(2), and one Cu(1) atom. In the second Cl site, Cl(2) is bonded in a square co-planar geometry to two equivalent K(2) and two equivalent Cu(1) atoms. In the third Cl site, Cl(3) is bonded to one K(1), two equivalent K(2), one Cu(1), and one Cu(2) atom to form distorted ClK3Cu2 trigonal bipyramids that share corners with three equivalent Cl(6)K4Cu2 octahedra, corners with three equivalent Cl(5)K3Cu2 trigonal bipyramids,  an edgeedge with one O(1)Cu4 tetrahedra,  an edgeedge with one Cl(3)K3Cu2 trigonal bipyramid, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 41-56°. In the fourth Cl site, Cl(4) is bonded in a 4-coordinate geometry to one K(2), three equivalent K(1), and one Cu(2) atom. In the fifth Cl site, Cl(5) is bonded to one K(1), two equivalent K(2), one Cu(1), and one Cu(2) atom to form distorted ClK3Cu2 trigonal bipyramids that share  a cornercorner with one Cl(6)K4Cu2 octahedra, corners with three equivalent Cl(3)K3Cu2 trigonal bipyramids,  an edgeedge with one Cl(6)K4Cu2 octahedra,  an edgeedge with one O(1)Cu4 tetrahedra,  an edgeedge with one Cl(5)K3Cu2 trigonal bipyramid, and edges with two equivalent Cl(3)K3Cu2 trigonal bipyramids. The corner-sharing octahedral tilt angles are 61°. In the sixth Cl site, Cl(6) is bonded to four equivalent K(1) and two equivalent Cu(2) atoms to form distorted ClK4Cu2 octahedra that share corners with two equivalent Cl(5)K3Cu2 trigonal bipyramids, corners with six equivalent Cl(3)K3Cu2 trigonal bipyramids, edges with two equivalent Cl(6)K4Cu2 octahedra,  an edgeedge with one O(1)Cu4 tetrahedra, and edges with two equivalent Cl(5)K3Cu2 trigonal bipyramids.