KEu(NiO3)4 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms. Eu(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(5) atoms to form distorted EuO12 cuboctahedra that share corners with four equivalent Eu(1)O12 cuboctahedra and faces with eight 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 and faces with two equivalent Eu(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-23°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one Eu(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Eu(1) and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Eu(1), and two equivalent Ni(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate 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 two equivalent Eu(1) and two equivalent Ni(1) atoms.
KEu(NiO3)4 crystallizes in the orthorhombic Amm2 space group. K(1) is bonded in a 10-coordinate geometry to two equivalent O(3), four equivalent O(1), and four equivalent O(4) atoms. Both K(1)-O(3) bond lengths are 2.71 Å. All K(1)-O(1) bond lengths are 2.60 Å. There are two shorter (2.62 Å) and two longer (2.80 Å) K(1)-O(4) bond lengths. Eu(1) is bonded to two equivalent O(2), two equivalent O(3), four equivalent O(1), and four equivalent O(5) atoms to form distorted EuO12 cuboctahedra that share corners with four equivalent Eu(1)O12 cuboctahedra and faces with eight equivalent Ni(1)O6 octahedra. Both Eu(1)-O(2) bond lengths are 2.40 Å. Both Eu(1)-O(3) bond lengths are 2.66 Å. All Eu(1)-O(1) bond lengths are 2.84 Å. There are two shorter (2.47 Å) and two longer (2.94 Å) Eu(1)-O(5) bond lengths. 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 and faces with two equivalent Eu(1)O12 cuboctahedra. The corner-sharing octahedral tilt angles range from 12-23°. The Ni(1)-O(2) bond length is 1.92 Å. The Ni(1)-O(3) bond length is 1.95 Å. The Ni(1)-O(4) bond length is 1.93 Å. The Ni(1)-O(5) bond length is 1.96 Å. There is one shorter (1.92 Å) and one longer (1.93 Å) Ni(1)-O(1) bond length. There are five inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one K(1), one Eu(1), and two equivalent Ni(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Eu(1) and two equivalent Ni(1) atoms. In the third O site, O(3) is bonded in a distorted rectangular see-saw-like geometry to one K(1), one Eu(1), and two equivalent Ni(1) atoms. In the fourth O site, O(4) is bonded in a 4-coordinate 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 two equivalent Eu(1) and two equivalent Ni(1) atoms.