Rb4TiO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. In the second Rb site, Rb(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted RbO4 trigonal pyramids that share corners with two equivalent Rb(3)O5 square pyramids, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Rb(3)O5 square pyramid, and  an edgeedge with one Rb(2)O4 trigonal pyramid. In the third Rb site, Rb(3) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form distorted RbO5 square pyramids that share corners with three equivalent Ti(1)O4 tetrahedra, corners with two equivalent Rb(2)O4 trigonal pyramids,  an edgeedge with one Rb(3)O5 square pyramid,  an edgeedge with one Ti(1)O4 tetrahedra, and  an edgeedge with one Rb(2)O4 trigonal pyramid. In the fourth Rb site, Rb(4) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(3), and three equivalent O(4) atoms. Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form TiO4 tetrahedra that share corners with three equivalent Rb(3)O5 square pyramids, corners with four equivalent Rb(2)O4 trigonal pyramids, and  an edgeedge with one Rb(3)O5 square pyramid. 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), one Rb(4), two equivalent Rb(1), and one Ti(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Rb(3), two equivalent Rb(1), two equivalent Rb(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and one Ti(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to two equivalent Rb(3), three equivalent Rb(4), and one Ti(1) atom.
Rb4TiO4 crystallizes in the monoclinic P2_1/c space group. There are four inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 5-coordinate geometry to one O(3), two equivalent O(1), and two equivalent O(2) atoms. The Rb(1)-O(3) bond length is 2.87 Å. There is one shorter (2.91 Å) and one longer (2.96 Å) Rb(1)-O(1) bond length. Both Rb(1)-O(2) bond lengths are 2.93 Å. In the second Rb site, Rb(2) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form distorted RbO4 trigonal pyramids that share corners with two equivalent Rb(3)O5 square pyramids, corners with four equivalent Ti(1)O4 tetrahedra,  an edgeedge with one Rb(3)O5 square pyramid, and  an edgeedge with one Rb(2)O4 trigonal pyramid. The Rb(2)-O(1) bond length is 2.84 Å. The Rb(2)-O(3) bond length is 2.74 Å. There is one shorter (2.73 Å) and one longer (2.80 Å) Rb(2)-O(2) bond length. In the third Rb site, Rb(3) is bonded to one O(1), one O(2), one O(3), and two equivalent O(4) atoms to form distorted RbO5 square pyramids that share corners with three equivalent Ti(1)O4 tetrahedra, corners with two equivalent Rb(2)O4 trigonal pyramids,  an edgeedge with one Rb(3)O5 square pyramid,  an edgeedge with one Ti(1)O4 tetrahedra, and  an edgeedge with one Rb(2)O4 trigonal pyramid. The Rb(3)-O(1) bond length is 2.89 Å. The Rb(3)-O(2) bond length is 3.16 Å. The Rb(3)-O(3) bond length is 2.80 Å. There is one shorter (2.77 Å) and one longer (2.85 Å) Rb(3)-O(4) bond length. In the fourth Rb site, Rb(4) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(3), and three equivalent O(4) atoms. The Rb(4)-O(1) bond length is 3.19 Å. There is one shorter (3.00 Å) and one longer (3.40 Å) Rb(4)-O(3) bond length. There are a spread of Rb(4)-O(4) bond distances ranging from 2.78-3.23 Å. Ti(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form TiO4 tetrahedra that share corners with three equivalent Rb(3)O5 square pyramids, corners with four equivalent Rb(2)O4 trigonal pyramids, and  an edgeedge with one Rb(3)O5 square pyramid. The Ti(1)-O(1) bond length is 1.85 Å. The Ti(1)-O(2) bond length is 1.84 Å. The Ti(1)-O(3) bond length is 1.84 Å. The Ti(1)-O(4) bond length is 1.82 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), one Rb(4), two equivalent Rb(1), and one Ti(1) atom. In the second O site, O(2) is bonded in a 1-coordinate geometry to one Rb(3), two equivalent Rb(1), two equivalent Rb(2), and one Ti(1) atom. In the third O site, O(3) is bonded in a 1-coordinate geometry to one Rb(1), one Rb(2), one Rb(3), two equivalent Rb(4), and one Ti(1) atom. In the fourth O site, O(4) is bonded in a 1-coordinate geometry to two equivalent Rb(3), three equivalent Rb(4), and one Ti(1) atom.