Ca(NiO2)2 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. In the second Ni site, Ni(2) is bonded to one O(2), two equivalent O(4), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Ni(1), and two equivalent Ni(2) atoms.
Ca(NiO2)2 crystallizes in the orthorhombic Pnma space group. Ca(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Ca(1)-O(1) bond lengths are 2.34 Å. There is one shorter (2.43 Å) and one longer (2.45 Å) Ca(1)-O(2) bond length. Both Ca(1)-O(3) bond lengths are 2.35 Å. Both Ca(1)-O(4) bond lengths are 2.42 Å. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded to one O(4), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. The Ni(1)-O(4) bond length is 1.96 Å. Both Ni(1)-O(2) bond lengths are 1.96 Å. There is one shorter (1.93 Å) and two longer (1.97 Å) Ni(1)-O(3) bond lengths. In the second Ni site, Ni(2) is bonded to one O(2), two equivalent O(4), and three equivalent O(1) atoms to form a mixture of edge and corner-sharing NiO6 octahedra. The corner-sharing octahedral tilt angles range from 49-57°. The Ni(2)-O(2) bond length is 1.96 Å. Both Ni(2)-O(4) bond lengths are 2.03 Å. There is one shorter (1.93 Å) and two longer (1.98 Å) Ni(2)-O(1) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ca(1) and three equivalent Ni(2) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the second O site, O(2) is bonded to two equivalent Ca(1), one Ni(2), and two equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 trigonal bipyramids. In the third O site, O(3) is bonded to two equivalent Ca(1) and three equivalent Ni(1) atoms to form a mixture of distorted edge and corner-sharing OCa2Ni3 square pyramids. In the fourth O site, O(4) is bonded in a 5-coordinate geometry to two equivalent Ca(1), one Ni(1), and two equivalent Ni(2) atoms.