K3GdCl6 crystallizes in the monoclinic P2_1/c space group. There are three 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), one Cl(6), two equivalent Cl(2), and two equivalent Cl(4) atoms. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Cl(2), one Cl(3), one Cl(5), two equivalent Cl(1), and two equivalent Cl(6) atoms. In the third K site, K(3) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(2), one Cl(5), one Cl(6), two equivalent Cl(3), and two equivalent Cl(4) atoms. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in an octahedral geometry to two equivalent Cl(2), two equivalent Cl(3), and two equivalent Cl(4) atoms. In the second Gd site, Gd(2) is bonded in an octahedral geometry to two equivalent Cl(1), two equivalent Cl(5), and two equivalent Cl(6) atoms. There are six inequivalent Cl sites. In the first Cl site, Cl(5) is bonded to one K(1), one K(2), one K(3), and one Gd(2) atom to form distorted ClK3Gd trigonal pyramids that share corners with four equivalent Cl(6)K4Gd square pyramids, corners with two equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(4)K4Gd trigonal bipyramids,  a cornercorner with one Cl(5)K3Gd trigonal pyramid,  an edgeedge with one Cl(6)K4Gd square pyramid,  an edgeedge with one Cl(3)K4Gd trigonal bipyramid, and  an edgeedge with one Cl(4)K4Gd trigonal bipyramid. In the second Cl site, Cl(6) is bonded to one K(1), one K(3), two equivalent K(2), and one Gd(2) atom to form distorted ClK4Gd square pyramids that share  a cornercorner with one Cl(6)K4Gd square pyramid,  a cornercorner with one Cl(3)K4Gd trigonal bipyramid, corners with two equivalent Cl(4)K4Gd trigonal bipyramids, corners with four equivalent Cl(5)K3Gd trigonal pyramids,  an edgeedge with one Cl(6)K4Gd square pyramid,  an edgeedge with one Cl(4)K4Gd trigonal bipyramid, edges with two equivalent Cl(3)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid. In the third Cl site, Cl(1) is bonded in a 5-coordinate geometry to one K(1), one K(3), two equivalent K(2), and one Gd(2) atom. In the fourth Cl site, Cl(2) is bonded in a 5-coordinate geometry to one K(2), one K(3), two equivalent K(1), and one Gd(1) atom. In the fifth Cl site, Cl(3) is bonded to one K(1), one K(2), two equivalent K(3), and one Gd(1) atom to form distorted ClK4Gd trigonal bipyramids that share  a cornercorner with one Cl(6)K4Gd square pyramid, corners with two equivalent Cl(4)K4Gd trigonal bipyramids, corners with three equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(5)K3Gd trigonal pyramids, edges with two equivalent Cl(6)K4Gd square pyramids, edges with three equivalent Cl(4)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid. In the sixth Cl site, Cl(4) is bonded to two equivalent K(1), two equivalent K(3), and one Gd(1) atom to form distorted ClK4Gd trigonal bipyramids that share corners with two equivalent Cl(6)K4Gd square pyramids,  a cornercorner with one Cl(4)K4Gd trigonal bipyramid, corners with two equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(5)K3Gd trigonal pyramids,  an edgeedge with one Cl(6)K4Gd square pyramid, edges with two equivalent Cl(4)K4Gd trigonal bipyramids, edges with three equivalent Cl(3)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid.
K3GdCl6 crystallizes in the monoclinic P2_1/c space group. There are three 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), one Cl(6), two equivalent Cl(2), and two equivalent Cl(4) atoms. The K(1)-Cl(1) bond length is 3.26 Å. The K(1)-Cl(3) bond length is 3.10 Å. The K(1)-Cl(5) bond length is 3.00 Å. The K(1)-Cl(6) bond length is 3.59 Å. There is one shorter (3.38 Å) and one longer (3.62 Å) K(1)-Cl(2) bond length. There is one shorter (3.25 Å) and one longer (3.28 Å) K(1)-Cl(4) bond length. In the second K site, K(2) is bonded in a 7-coordinate geometry to one Cl(2), one Cl(3), one Cl(5), two equivalent Cl(1), and two equivalent Cl(6) atoms. The K(2)-Cl(2) bond length is 3.68 Å. The K(2)-Cl(3) bond length is 3.35 Å. The K(2)-Cl(5) bond length is 3.16 Å. There is one shorter (3.26 Å) and one longer (3.65 Å) K(2)-Cl(1) bond length. There is one shorter (3.16 Å) and one longer (3.48 Å) K(2)-Cl(6) bond length. In the third K site, K(3) is bonded in a 8-coordinate geometry to one Cl(1), one Cl(2), one Cl(5), one Cl(6), two equivalent Cl(3), and two equivalent Cl(4) atoms. The K(3)-Cl(1) bond length is 3.44 Å. The K(3)-Cl(2) bond length is 3.15 Å. The K(3)-Cl(5) bond length is 3.13 Å. The K(3)-Cl(6) bond length is 3.28 Å. There is one shorter (3.32 Å) and one longer (3.59 Å) K(3)-Cl(3) bond length. There is one shorter (3.17 Å) and one longer (3.22 Å) K(3)-Cl(4) bond length. There are two inequivalent Gd sites. In the first Gd site, Gd(1) is bonded in an octahedral geometry to two equivalent Cl(2), two equivalent Cl(3), and two equivalent Cl(4) atoms. Both Gd(1)-Cl(2) bond lengths are 2.66 Å. Both Gd(1)-Cl(3) bond lengths are 2.68 Å. Both Gd(1)-Cl(4) bond lengths are 2.70 Å. In the second Gd site, Gd(2) is bonded in an octahedral geometry to two equivalent Cl(1), two equivalent Cl(5), and two equivalent Cl(6) atoms. Both Gd(2)-Cl(1) bond lengths are 2.63 Å. Both Gd(2)-Cl(5) bond lengths are 2.65 Å. Both Gd(2)-Cl(6) bond lengths are 2.71 Å. There are six inequivalent Cl sites. In the first Cl site, Cl(5) is bonded to one K(1), one K(2), one K(3), and one Gd(2) atom to form distorted ClK3Gd trigonal pyramids that share corners with four equivalent Cl(6)K4Gd square pyramids, corners with two equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(4)K4Gd trigonal bipyramids,  a cornercorner with one Cl(5)K3Gd trigonal pyramid,  an edgeedge with one Cl(6)K4Gd square pyramid,  an edgeedge with one Cl(3)K4Gd trigonal bipyramid, and  an edgeedge with one Cl(4)K4Gd trigonal bipyramid. In the second Cl site, Cl(6) is bonded to one K(1), one K(3), two equivalent K(2), and one Gd(2) atom to form distorted ClK4Gd square pyramids that share  a cornercorner with one Cl(6)K4Gd square pyramid,  a cornercorner with one Cl(3)K4Gd trigonal bipyramid, corners with two equivalent Cl(4)K4Gd trigonal bipyramids, corners with four equivalent Cl(5)K3Gd trigonal pyramids,  an edgeedge with one Cl(6)K4Gd square pyramid,  an edgeedge with one Cl(4)K4Gd trigonal bipyramid, edges with two equivalent Cl(3)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid. In the third Cl site, Cl(1) is bonded in a 5-coordinate geometry to one K(1), one K(3), two equivalent K(2), and one Gd(2) atom. In the fourth Cl site, Cl(2) is bonded in a 5-coordinate geometry to one K(2), one K(3), two equivalent K(1), and one Gd(1) atom. In the fifth Cl site, Cl(3) is bonded to one K(1), one K(2), two equivalent K(3), and one Gd(1) atom to form distorted ClK4Gd trigonal bipyramids that share  a cornercorner with one Cl(6)K4Gd square pyramid, corners with two equivalent Cl(4)K4Gd trigonal bipyramids, corners with three equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(5)K3Gd trigonal pyramids, edges with two equivalent Cl(6)K4Gd square pyramids, edges with three equivalent Cl(4)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid. In the sixth Cl site, Cl(4) is bonded to two equivalent K(1), two equivalent K(3), and one Gd(1) atom to form distorted ClK4Gd trigonal bipyramids that share corners with two equivalent Cl(6)K4Gd square pyramids,  a cornercorner with one Cl(4)K4Gd trigonal bipyramid, corners with two equivalent Cl(3)K4Gd trigonal bipyramids, corners with two equivalent Cl(5)K3Gd trigonal pyramids,  an edgeedge with one Cl(6)K4Gd square pyramid, edges with two equivalent Cl(4)K4Gd trigonal bipyramids, edges with three equivalent Cl(3)K4Gd trigonal bipyramids, and  an edgeedge with one Cl(5)K3Gd trigonal pyramid.