NiO2 crystallizes in the triclinic P1 space group. There are twelve inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(2), one O(4), one O(6), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. In the third Ni site, Ni(3) is bonded to one O(10), one O(11), one O(14), one O(15), one O(17), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(9)O6 octahedra. In the fourth Ni site, Ni(4) is bonded to one O(1), one O(12), one O(2), one O(3), one O(8), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. In the fifth Ni site, Ni(5) is bonded to one O(11), one O(14), one O(17), one O(20), one O(5), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(9)O6 octahedra. In the sixth Ni site, Ni(6) is bonded to one O(13), one O(14), one O(15), one O(18), one O(19), and one O(20) atom to form edge-sharing NiO6 octahedra. In the seventh Ni site, Ni(7) is bonded to one O(12), one O(17), one O(6), and one O(8) atom to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-59°. In the eighth Ni site, Ni(8) is bonded to one O(16), one O(18), one O(19), one O(21), one O(22), and one O(23) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(10)O6 octahedra, and edges with two equivalent Ni(11)O6 octahedra. In the ninth Ni site, Ni(9) is bonded to one O(10), one O(15), one O(17), one O(20), one O(5), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. In the tenth Ni site, Ni(10) is bonded to one O(13), one O(16), one O(19), one O(21), one O(23), and one O(24) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(11)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. In the eleventh Ni site, Ni(11) is bonded to one O(13), one O(16), one O(18), one O(22), one O(23), and one O(24) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(10)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. In the twelfth Ni site, Ni(12) is bonded to one O(21), one O(22), one O(24), and one O(9) atom to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-59°. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one Ni(2) and one Ni(4) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Ni(4) atom. In the third O site, O(3) is bonded in a water-like geometry to one Ni(1) and one Ni(4) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one Ni(1) and one Ni(2) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Ni(5) and one Ni(9) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Ni(1), one Ni(2), and one Ni(7) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(5), and one Ni(9) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Ni(1), one Ni(4), and one Ni(7) atom. In the ninth O site, O(9) is bonded in a distorted trigonal pyramidal geometry to one Ni(1), one Ni(12), one Ni(2), and one Ni(4) atom. In the tenth O site, O(10) is bonded in a water-like geometry to one Ni(3) and one Ni(9) atom. In the eleventh O site, O(11) is bonded in a water-like geometry to one Ni(3) and one Ni(5) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Ni(2), one Ni(4), and one Ni(7) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(6) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(5), and one Ni(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(6), and one Ni(9) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(8) atom. In the seventeenth O site, O(17) is bonded in a distorted trigonal pyramidal geometry to one Ni(3), one Ni(5), one Ni(7), and one Ni(9) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Ni(11), one Ni(6), and one Ni(8) atom. In the nineteenth O site, O(19) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(6), and one Ni(8) atom. In the twentieth O site, O(20) is bonded in a distorted T-shaped geometry to one Ni(5), one Ni(6), and one Ni(9) atom. In the twenty-first O site, O(21) is bonded in a trigonal planar geometry to one Ni(10), one Ni(12), and one Ni(8) atom. In the twenty-second O site, O(22) is bonded in a trigonal planar geometry to one Ni(11), one Ni(12), and one Ni(8) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(8) atom. In the twenty-fourth O site, O(24) is bonded in a trigonal planar geometry to one Ni(10), one Ni(11), and one Ni(12) atom.
NiO2 crystallizes in the triclinic P1 space group. There are twelve inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(2), one O(3), one O(4), one O(6), one O(8), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(2)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The Ni(1)-O(2) bond length is 1.88 Å. The Ni(1)-O(3) bond length is 1.84 Å. The Ni(1)-O(4) bond length is 1.83 Å. The Ni(1)-O(6) bond length is 1.86 Å. The Ni(1)-O(8) bond length is 1.86 Å. The Ni(1)-O(9) bond length is 1.92 Å. In the second Ni site, Ni(2) is bonded to one O(1), one O(12), one O(2), one O(4), one O(6), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(4)O6 octahedra. The Ni(2)-O(1) bond length is 1.83 Å. The Ni(2)-O(12) bond length is 1.86 Å. The Ni(2)-O(2) bond length is 1.88 Å. The Ni(2)-O(4) bond length is 1.83 Å. The Ni(2)-O(6) bond length is 1.86 Å. The Ni(2)-O(9) bond length is 1.91 Å. In the third Ni site, Ni(3) is bonded to one O(10), one O(11), one O(14), one O(15), one O(17), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(5)O6 octahedra, and edges with two equivalent Ni(9)O6 octahedra. The Ni(3)-O(10) bond length is 1.85 Å. The Ni(3)-O(11) bond length is 1.85 Å. The Ni(3)-O(14) bond length is 1.88 Å. The Ni(3)-O(15) bond length is 1.89 Å. The Ni(3)-O(17) bond length is 1.91 Å. The Ni(3)-O(7) bond length is 1.87 Å. In the fourth Ni site, Ni(4) is bonded to one O(1), one O(12), one O(2), one O(3), one O(8), and one O(9) atom to form NiO6 octahedra that share  a cornercorner with one Ni(12)O4 tetrahedra, corners with two equivalent Ni(7)O4 tetrahedra, edges with two equivalent Ni(1)O6 octahedra, and edges with two equivalent Ni(2)O6 octahedra. The Ni(4)-O(1) bond length is 1.83 Å. The Ni(4)-O(12) bond length is 1.86 Å. The Ni(4)-O(2) bond length is 1.88 Å. The Ni(4)-O(3) bond length is 1.83 Å. The Ni(4)-O(8) bond length is 1.86 Å. The Ni(4)-O(9) bond length is 1.91 Å. In the fifth Ni site, Ni(5) is bonded to one O(11), one O(14), one O(17), one O(20), one O(5), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(9)O6 octahedra. The Ni(5)-O(11) bond length is 1.85 Å. The Ni(5)-O(14) bond length is 1.88 Å. The Ni(5)-O(17) bond length is 1.91 Å. The Ni(5)-O(20) bond length is 1.89 Å. The Ni(5)-O(5) bond length is 1.85 Å. The Ni(5)-O(7) bond length is 1.87 Å. In the sixth Ni site, Ni(6) is bonded to one O(13), one O(14), one O(15), one O(18), one O(19), and one O(20) atom to form edge-sharing NiO6 octahedra. The Ni(6)-O(13) bond length is 1.88 Å. The Ni(6)-O(14) bond length is 1.89 Å. The Ni(6)-O(15) bond length is 1.89 Å. The Ni(6)-O(18) bond length is 1.89 Å. The Ni(6)-O(19) bond length is 1.89 Å. The Ni(6)-O(20) bond length is 1.89 Å. In the seventh Ni site, Ni(7) is bonded to one O(12), one O(17), one O(6), and one O(8) atom to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-59°. The Ni(7)-O(12) bond length is 1.89 Å. The Ni(7)-O(17) bond length is 2.05 Å. The Ni(7)-O(6) bond length is 1.89 Å. The Ni(7)-O(8) bond length is 1.89 Å. In the eighth Ni site, Ni(8) is bonded to one O(16), one O(18), one O(19), one O(21), one O(22), and one O(23) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(10)O6 octahedra, and edges with two equivalent Ni(11)O6 octahedra. The Ni(8)-O(16) bond length is 1.89 Å. The Ni(8)-O(18) bond length is 1.88 Å. The Ni(8)-O(19) bond length is 1.88 Å. The Ni(8)-O(21) bond length is 1.86 Å. The Ni(8)-O(22) bond length is 1.86 Å. The Ni(8)-O(23) bond length is 1.88 Å. In the ninth Ni site, Ni(9) is bonded to one O(10), one O(15), one O(17), one O(20), one O(5), and one O(7) atom to form NiO6 octahedra that share  a cornercorner with one Ni(7)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(3)O6 octahedra, and edges with two equivalent Ni(5)O6 octahedra. The Ni(9)-O(10) bond length is 1.85 Å. The Ni(9)-O(15) bond length is 1.88 Å. The Ni(9)-O(17) bond length is 1.91 Å. The Ni(9)-O(20) bond length is 1.88 Å. The Ni(9)-O(5) bond length is 1.85 Å. The Ni(9)-O(7) bond length is 1.87 Å. In the tenth Ni site, Ni(10) is bonded to one O(13), one O(16), one O(19), one O(21), one O(23), and one O(24) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(11)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. The Ni(10)-O(13) bond length is 1.88 Å. The Ni(10)-O(16) bond length is 1.89 Å. The Ni(10)-O(19) bond length is 1.88 Å. The Ni(10)-O(21) bond length is 1.86 Å. The Ni(10)-O(23) bond length is 1.88 Å. The Ni(10)-O(24) bond length is 1.86 Å. In the eleventh Ni site, Ni(11) is bonded to one O(13), one O(16), one O(18), one O(22), one O(23), and one O(24) atom to form NiO6 octahedra that share corners with two equivalent Ni(12)O4 tetrahedra,  an edgeedge with one Ni(6)O6 octahedra, edges with two equivalent Ni(10)O6 octahedra, and edges with two equivalent Ni(8)O6 octahedra. The Ni(11)-O(13) bond length is 1.88 Å. The Ni(11)-O(16) bond length is 1.89 Å. The Ni(11)-O(18) bond length is 1.88 Å. The Ni(11)-O(22) bond length is 1.86 Å. The Ni(11)-O(23) bond length is 1.88 Å. The Ni(11)-O(24) bond length is 1.86 Å. In the twelfth Ni site, Ni(12) is bonded to one O(21), one O(22), one O(24), and one O(9) atom to form corner-sharing NiO4 tetrahedra. The corner-sharing octahedral tilt angles range from 57-59°. The Ni(12)-O(21) bond length is 1.89 Å. The Ni(12)-O(22) bond length is 1.89 Å. The Ni(12)-O(24) bond length is 1.89 Å. The Ni(12)-O(9) bond length is 2.07 Å. There are twenty-four inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to one Ni(2) and one Ni(4) atom. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Ni(1), one Ni(2), and one Ni(4) atom. In the third O site, O(3) is bonded in a water-like geometry to one Ni(1) and one Ni(4) atom. In the fourth O site, O(4) is bonded in a water-like geometry to one Ni(1) and one Ni(2) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Ni(5) and one Ni(9) atom. In the sixth O site, O(6) is bonded in a trigonal planar geometry to one Ni(1), one Ni(2), and one Ni(7) atom. In the seventh O site, O(7) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(5), and one Ni(9) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Ni(1), one Ni(4), and one Ni(7) atom. In the ninth O site, O(9) is bonded in a distorted trigonal pyramidal geometry to one Ni(1), one Ni(12), one Ni(2), and one Ni(4) atom. In the tenth O site, O(10) is bonded in a water-like geometry to one Ni(3) and one Ni(9) atom. In the eleventh O site, O(11) is bonded in a water-like geometry to one Ni(3) and one Ni(5) atom. In the twelfth O site, O(12) is bonded in a trigonal planar geometry to one Ni(2), one Ni(4), and one Ni(7) atom. In the thirteenth O site, O(13) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(6) atom. In the fourteenth O site, O(14) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(5), and one Ni(6) atom. In the fifteenth O site, O(15) is bonded in a distorted T-shaped geometry to one Ni(3), one Ni(6), and one Ni(9) atom. In the sixteenth O site, O(16) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(8) atom. In the seventeenth O site, O(17) is bonded in a distorted trigonal pyramidal geometry to one Ni(3), one Ni(5), one Ni(7), and one Ni(9) atom. In the eighteenth O site, O(18) is bonded in a distorted T-shaped geometry to one Ni(11), one Ni(6), and one Ni(8) atom. In the nineteenth O site, O(19) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(6), and one Ni(8) atom. In the twentieth O site, O(20) is bonded in a distorted T-shaped geometry to one Ni(5), one Ni(6), and one Ni(9) atom. In the twenty-first O site, O(21) is bonded in a trigonal planar geometry to one Ni(10), one Ni(12), and one Ni(8) atom. In the twenty-second O site, O(22) is bonded in a trigonal planar geometry to one Ni(11), one Ni(12), and one Ni(8) atom. In the twenty-third O site, O(23) is bonded in a distorted T-shaped geometry to one Ni(10), one Ni(11), and one Ni(8) atom. In the twenty-fourth O site, O(24) is bonded in a trigonal planar geometry to one Ni(10), one Ni(11), and one Ni(12) atom.