Rb2NiF4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Rb(1) is bonded in a 9-coordinate geometry to four equivalent F(1) and five equivalent F(2) atoms. Ni(1) is bonded to two equivalent F(2) and four equivalent F(1) atoms to form corner-sharing NiF6 octahedra. The corner-sharing octahedra are not tilted. There are two inequivalent F sites. In the first F site, F(2) is bonded to five equivalent Rb(1) and one Ni(1) atom to form distorted FRb5Ni octahedra that share corners with five equivalent F(2)Rb5Ni octahedra, corners with twelve equivalent F(1)Rb4Ni2 octahedra, edges with eight equivalent F(2)Rb5Ni octahedra, and faces with four equivalent F(1)Rb4Ni2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second F site, F(1) is bonded to four equivalent Rb(1) and two equivalent Ni(1) atoms to form distorted FRb4Ni2 octahedra that share corners with two equivalent F(1)Rb4Ni2 octahedra, corners with twelve equivalent F(2)Rb5Ni octahedra, edges with two equivalent F(1)Rb4Ni2 octahedra, faces with four equivalent F(1)Rb4Ni2 octahedra, and faces with four equivalent F(2)Rb5Ni octahedra. The corner-sharing octahedral tilt angles range from 0-60°.
Rb2NiF4 is (La,Ba)CuO4 structured and crystallizes in the tetragonal I4/mmm space group. Rb(1) is bonded in a 9-coordinate geometry to four equivalent F(1) and five equivalent F(2) atoms. All Rb(1)-F(1) bond lengths are 2.86 Å. There is one shorter (2.83 Å) and four longer (2.89 Å) Rb(1)-F(2) bond lengths. Ni(1) is bonded to two equivalent F(2) and four equivalent F(1) atoms to form corner-sharing NiF6 octahedra. The corner-sharing octahedra are not tilted. Both Ni(1)-F(2) bond lengths are 2.00 Å. All Ni(1)-F(1) bond lengths are 2.04 Å. There are two inequivalent F sites. In the first F site, F(2) is bonded to five equivalent Rb(1) and one Ni(1) atom to form distorted FRb5Ni octahedra that share corners with five equivalent F(2)Rb5Ni octahedra, corners with twelve equivalent F(1)Rb4Ni2 octahedra, edges with eight equivalent F(2)Rb5Ni octahedra, and faces with four equivalent F(1)Rb4Ni2 octahedra. The corner-sharing octahedral tilt angles range from 0-60°. In the second F site, F(1) is bonded to four equivalent Rb(1) and two equivalent Ni(1) atoms to form distorted FRb4Ni2 octahedra that share corners with two equivalent F(1)Rb4Ni2 octahedra, corners with twelve equivalent F(2)Rb5Ni octahedra, edges with two equivalent F(1)Rb4Ni2 octahedra, faces with four equivalent F(1)Rb4Ni2 octahedra, and faces with four equivalent F(2)Rb5Ni octahedra. The corner-sharing octahedral tilt angles range from 0-60°.