RbTiNbO5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. Ti(1) is bonded to one O(1), one O(3), one O(4), and three equivalent O(5) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-29°. Nb(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and edges with three equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-34°. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one Ti(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Rb(1), one Ti(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to three equivalent Ti(1) and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OTi3Nb trigonal pyramids.
RbTiNbO5 crystallizes in the orthorhombic Pnma space group. Rb(1) is bonded in a 8-coordinate geometry to two equivalent O(3), two equivalent O(4), and four equivalent O(2) atoms. Both Rb(1)-O(3) bond lengths are 2.91 Å. Both Rb(1)-O(4) bond lengths are 3.17 Å. There are two shorter (2.93 Å) and two longer (3.08 Å) Rb(1)-O(2) bond lengths. Ti(1) is bonded to one O(1), one O(3), one O(4), and three equivalent O(5) atoms to form distorted TiO6 octahedra that share  a cornercorner with one Nb(1)O6 octahedra, corners with two equivalent Ti(1)O6 octahedra, edges with two equivalent Ti(1)O6 octahedra, and edges with three equivalent Nb(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-29°. The Ti(1)-O(1) bond length is 2.15 Å. The Ti(1)-O(3) bond length is 1.86 Å. The Ti(1)-O(4) bond length is 1.79 Å. There are two shorter (1.98 Å) and one longer (2.23 Å) Ti(1)-O(5) bond length. Nb(1) is bonded to one O(2), one O(3), one O(4), one O(5), and two equivalent O(1) atoms to form distorted NbO6 octahedra that share  a cornercorner with one Ti(1)O6 octahedra, corners with two equivalent Nb(1)O6 octahedra, and edges with three equivalent Ti(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 4-34°. The Nb(1)-O(2) bond length is 1.80 Å. The Nb(1)-O(3) bond length is 2.00 Å. The Nb(1)-O(4) bond length is 2.03 Å. The Nb(1)-O(5) bond length is 2.38 Å. Both Nb(1)-O(1) bond lengths are 2.00 Å. There are five inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal non-coplanar geometry to one Ti(1) and two equivalent Nb(1) atoms. In the second O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Rb(1) and one Nb(1) atom. In the third O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Rb(1), one Ti(1), and one Nb(1) atom. In the fourth O site, O(4) is bonded in a distorted linear geometry to two equivalent Rb(1), one Ti(1), and one Nb(1) atom. In the fifth O site, O(5) is bonded to three equivalent Ti(1) and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OTi3Nb trigonal pyramids.