KNpO3 is (Cubic) Perovskite structured and crystallizes in the tetragonal P4/mmm space group. K(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form KO12 cuboctahedra that share corners with twelve equivalent K(1)O12 cuboctahedra, faces with six equivalent K(1)O12 cuboctahedra, and faces with eight equivalent Np(1)O6 octahedra. Np(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NpO6 octahedra that share corners with six equivalent Np(1)O6 octahedra and faces with eight equivalent K(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Np(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Np(1) atoms.
KNpO3 is (Cubic) Perovskite structured and crystallizes in the tetragonal P4/mmm space group. K(1) is bonded to four equivalent O(2) and eight equivalent O(1) atoms to form KO12 cuboctahedra that share corners with twelve equivalent K(1)O12 cuboctahedra, faces with six equivalent K(1)O12 cuboctahedra, and faces with eight equivalent Np(1)O6 octahedra. All K(1)-O(2) bond lengths are 3.04 Å. All K(1)-O(1) bond lengths are 3.03 Å. Np(1) is bonded to two equivalent O(2) and four equivalent O(1) atoms to form NpO6 octahedra that share corners with six equivalent Np(1)O6 octahedra and faces with eight equivalent K(1)O12 cuboctahedra. The corner-sharing octahedra are not tilted. Both Np(1)-O(2) bond lengths are 2.14 Å. All Np(1)-O(1) bond lengths are 2.15 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Np(1) atoms. In the second O site, O(2) is bonded in a distorted linear geometry to four equivalent K(1) and two equivalent Np(1) atoms.