NaNi2O3 is Caswellsilverite-like structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with four equivalent Ni(6)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Ni(3)O6 octahedra, corners with four equivalent Ni(5)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-12°. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(3)O6 octahedra, corners with four equivalent Ni(5)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. In the second Ni site, Ni(2) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent Ni(4)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with four equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-7°. In the third Ni site, Ni(3) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with four equivalent Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with four equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. In the fifth Ni site, Ni(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. In the sixth Ni site, Ni(6) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(4)O6 octahedra, corners with four equivalent Na(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-13°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(2), one Ni(2), one Ni(4), and two equivalent Ni(5) atoms to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second O site, O(2) is bonded to two equivalent Na(1), one Ni(1), one Ni(3), and two equivalent Ni(6) atoms to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Ni(1), one Ni(3), one Ni(5), and one Ni(6) atom to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°.
NaNi2O3 is Caswellsilverite-like structured and crystallizes in the monoclinic P2/m space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with four equivalent Ni(6)O6 octahedra,  an edgeedge with one Na(1)O6 octahedra,  an edgeedge with one Ni(4)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-11°. Both Na(1)-O(2) bond lengths are 2.26 Å. Both Na(1)-O(3) bond lengths are 2.34 Å. Both Na(1)-O(4) bond lengths are 2.32 Å. In the second Na site, Na(2) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NaO6 octahedra that share corners with two equivalent Ni(3)O6 octahedra, corners with four equivalent Ni(5)O6 octahedra,  an edgeedge with one Na(2)O6 octahedra,  an edgeedge with one Ni(1)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-12°. Both Na(2)-O(1) bond lengths are 2.26 Å. Both Na(2)-O(3) bond lengths are 2.29 Å. Both Na(2)-O(4) bond lengths are 2.33 Å. There are six inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(3)O6 octahedra, corners with four equivalent Ni(5)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. Both Ni(1)-O(2) bond lengths are 2.11 Å. All Ni(1)-O(4) bond lengths are 2.16 Å. In the second Ni site, Ni(2) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent Ni(4)O6 octahedra, corners with four equivalent Na(1)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, edges with two equivalent Ni(6)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with four equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-7°. Both Ni(2)-O(1) bond lengths are 2.31 Å. All Ni(2)-O(3) bond lengths are 1.92 Å. In the third Ni site, Ni(3) is bonded to two equivalent O(2) and four equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, edges with four equivalent Na(1)O6 octahedra, and edges with four equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-8°. Both Ni(3)-O(2) bond lengths are 2.25 Å. All Ni(3)-O(4) bond lengths are 1.93 Å. In the fourth Ni site, Ni(4) is bonded to two equivalent O(1) and four equivalent O(3) atoms to form NiO6 octahedra that share corners with two equivalent Ni(2)O6 octahedra, corners with four equivalent Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with four equivalent Na(2)O6 octahedra, and edges with four equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 7-13°. Both Ni(4)-O(1) bond lengths are 2.05 Å. All Ni(4)-O(3) bond lengths are 2.17 Å. In the fifth Ni site, Ni(5) is bonded to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(1)O6 octahedra, corners with four equivalent Na(2)O6 octahedra,  an edgeedge with one Ni(3)O6 octahedra,  an edgeedge with one Ni(5)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(2)O6 octahedra, edges with two equivalent Ni(4)O6 octahedra, and edges with two equivalent Ni(6)O6 octahedra. The corner-sharing octahedral tilt angles range from 8-14°. Both Ni(5)-O(1) bond lengths are 2.04 Å. Both Ni(5)-O(3) bond lengths are 2.08 Å. Both Ni(5)-O(4) bond lengths are 2.15 Å. In the sixth Ni site, Ni(6) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form NiO6 octahedra that share corners with two equivalent Ni(4)O6 octahedra, corners with four equivalent Na(1)O6 octahedra,  an edgeedge with one Ni(2)O6 octahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Na(1)O6 octahedra, edges with two equivalent Na(2)O6 octahedra, edges with two equivalent Ni(1)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The corner-sharing octahedral tilt angles range from 6-13°. Both Ni(6)-O(2) bond lengths are 2.01 Å. Both Ni(6)-O(3) bond lengths are 2.15 Å. Both Ni(6)-O(4) bond lengths are 2.05 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Na(2), one Ni(2), one Ni(4), and two equivalent Ni(5) atoms to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the second O site, O(2) is bonded to two equivalent Na(1), one Ni(1), one Ni(3), and two equivalent Ni(6) atoms to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-6°. In the third O site, O(3) is bonded to one Na(1), one Na(2), one Ni(2), one Ni(4), one Ni(5), and one Ni(6) atom to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°. In the fourth O site, O(4) is bonded to one Na(1), one Na(2), one Ni(1), one Ni(3), one Ni(5), and one Ni(6) atom to form a mixture of edge and corner-sharing ONa2Ni4 octahedra. The corner-sharing octahedral tilt angles range from 0-8°.