Rb5NiSi2O8 crystallizes in the monoclinic C2/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Ni(1) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. Si(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), two equivalent Rb(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(2), two equivalent Rb(1), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Ni(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), two equivalent Rb(2), and one Si(1) atom.
Rb5NiSi2O8 crystallizes in the monoclinic C2/c space group. There are three inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 6-coordinate geometry to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms. The Rb(1)-O(3) bond length is 2.91 Å. The Rb(1)-O(4) bond length is 3.46 Å. There is one shorter (2.90 Å) and one longer (3.08 Å) Rb(1)-O(1) bond length. There is one shorter (2.77 Å) and one longer (3.39 Å) Rb(1)-O(2) bond length. In the second Rb site, Rb(2) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), and two equivalent O(4) atoms. The Rb(2)-O(1) bond length is 2.87 Å. The Rb(2)-O(2) bond length is 3.11 Å. The Rb(2)-O(3) bond length is 2.89 Å. There is one shorter (2.91 Å) and one longer (3.04 Å) Rb(2)-O(4) bond length. In the third Rb site, Rb(3) is bonded in a 6-coordinate geometry to two equivalent O(1), two equivalent O(3), and two equivalent O(4) atoms. Both Rb(3)-O(1) bond lengths are 2.75 Å. Both Rb(3)-O(3) bond lengths are 3.16 Å. Both Rb(3)-O(4) bond lengths are 2.88 Å. Ni(1) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Ni(1)-O(2) bond lengths are 1.90 Å. Both Ni(1)-O(3) bond lengths are 1.83 Å. Si(1) is bonded in a tetrahedral geometry to one O(1), one O(2), one O(3), and one O(4) atom. The Si(1)-O(1) bond length is 1.61 Å. The Si(1)-O(2) bond length is 1.71 Å. The Si(1)-O(3) bond length is 1.73 Å. The Si(1)-O(4) bond length is 1.62 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one Rb(2), one Rb(3), two equivalent Rb(1), and one Si(1) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Rb(2), two equivalent Rb(1), one Ni(1), and one Si(1) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), one Ni(1), and one Si(1) atom. In the fourth O site, O(4) is bonded in a distorted single-bond geometry to one Rb(1), one Rb(3), two equivalent Rb(2), and one Si(1) atom.