KSm(NiO3)4 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(1)O12 cuboctahedra, corners with eight equivalent Sm(1)O10 cuboctahedra, and faces with eight equivalent Ni(1)O6 octahedra. Sm(1) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms to form distorted SmO10 cuboctahedra that share corners with eight equivalent K(1)O12 cuboctahedra, edges with four equivalent Ni(1)O6 octahedra, and faces with four equivalent Ni(1)O6 octahedra. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra,  an edgeedge with one Sm(1)O10 cuboctahedra,  a faceface with one Sm(1)O10 cuboctahedra, and faces with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-21°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted square co-planar geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the fourth O site, O(4) is bonded in a distorted square co-planar geometry to two equivalent K(1) and two equivalent Ni(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sm(1) and two equivalent Ni(1) atoms.
KSm(NiO3)4 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms to form distorted KO12 cuboctahedra that share corners with four equivalent K(1)O12 cuboctahedra, corners with eight equivalent Sm(1)O10 cuboctahedra, and faces with eight equivalent Ni(1)O6 octahedra. Both K(1)-O(2) bond lengths are 3.09 Å. Both K(1)-O(3) bond lengths are 2.81 Å. All K(1)-O(1) bond lengths are 2.88 Å. There are two shorter (2.67 Å) and two longer (2.75 Å) K(1)-O(4) bond lengths. Sm(1) is bonded to two equivalent O(2), two equivalent O(3), two equivalent O(5), and four equivalent O(1) atoms to form distorted SmO10 cuboctahedra that share corners with eight equivalent K(1)O12 cuboctahedra, edges with four equivalent Ni(1)O6 octahedra, and faces with four equivalent Ni(1)O6 octahedra. Both Sm(1)-O(2) bond lengths are 2.46 Å. Both Sm(1)-O(3) bond lengths are 2.50 Å. Both Sm(1)-O(5) bond lengths are 2.50 Å. All Sm(1)-O(1) bond lengths are 2.52 Å. Ni(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form NiO6 octahedra that share corners with six equivalent Ni(1)O6 octahedra,  an edgeedge with one Sm(1)O10 cuboctahedra,  a faceface with one Sm(1)O10 cuboctahedra, and faces with two equivalent K(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 6-21°. The Ni(1)-O(2) bond length is 1.92 Å. The Ni(1)-O(3) bond length is 1.93 Å. The Ni(1)-O(4) bond length is 1.89 Å. The Ni(1)-O(5) bond length is 1.94 Å. Both Ni(1)-O(1) bond lengths are 1.94 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted square co-planar geometry to one K(1), one Sm(1), and two equivalent Ni(1) atoms. In the fourth O site, O(4) is bonded in a distorted square co-planar geometry to two equivalent K(1) and two equivalent Ni(1) atoms. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to one Sm(1) and two equivalent Ni(1) atoms.