Rb2Ni2O3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to three equivalent O(1) and four equivalent O(2) atoms. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. In the second Ni site, Ni(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), three equivalent Rb(2), one Ni(1), and one Ni(2) atom to form a mixture of distorted corner and edge-sharing ORb4Ni2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Ni(1), and one Ni(2) atom.
Rb2Ni2O3 crystallizes in the orthorhombic Pnma space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(1) and four equivalent O(2) atoms. The Rb(1)-O(1) bond length is 2.93 Å. All Rb(1)-O(2) bond lengths are 2.92 Å. In the second Rb site, Rb(2) is bonded in a 7-coordinate geometry to three equivalent O(1) and four equivalent O(2) atoms. There is one shorter (2.90 Å) and two longer (3.08 Å) Rb(2)-O(1) bond lengths. There are two shorter (3.19 Å) and two longer (3.30 Å) Rb(2)-O(2) bond lengths. There are two inequivalent Ni sites. In the first Ni site, Ni(1) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Ni(1)-O(1) bond length is 1.86 Å. Both Ni(1)-O(2) bond lengths are 1.85 Å. In the second Ni site, Ni(2) is bonded in a trigonal planar geometry to one O(1) and two equivalent O(2) atoms. The Ni(2)-O(1) bond length is 1.87 Å. Both Ni(2)-O(2) bond lengths are 1.86 Å. There are two inequivalent O sites. In the first O site, O(1) is bonded to one Rb(1), three equivalent Rb(2), one Ni(1), and one Ni(2) atom to form a mixture of distorted corner and edge-sharing ORb4Ni2 octahedra. The corner-sharing octahedral tilt angles are 3°. In the second O site, O(2) is bonded in a 2-coordinate geometry to two equivalent Rb(1), two equivalent Rb(2), one Ni(1), and one Ni(2) atom.