Rb2MgNb2(TeO6)2 crystallizes in the triclinic P1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 3-coordinate geometry to one O(11), one O(7), and one O(9) atom. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(3), one O(5), and one O(8) atom. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(5), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(6), one O(8), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-44°. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(11), one O(3), and one O(7) atom. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in an L-shaped geometry to one Mg(1) and one Te(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(2), one Mg(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Mg(1) and one Nb(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Te(1), and one Te(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Rb(1) and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(1), and one Te(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Rb(2), one Mg(1), one Nb(2), and one Te(1) atom.
Rb2MgNb2(TeO6)2 crystallizes in the triclinic P1 space group. There are two inequivalent Rb sites. In the first Rb site, Rb(1) is bonded in a 3-coordinate geometry to one O(11), one O(7), and one O(9) atom. The Rb(1)-O(11) bond length is 3.09 Å. The Rb(1)-O(7) bond length is 3.20 Å. The Rb(1)-O(9) bond length is 3.04 Å. In the second Rb site, Rb(2) is bonded in a 8-coordinate geometry to one O(10), one O(12), one O(2), one O(3), one O(4), one O(6), one O(7), and one O(8) atom. The Rb(2)-O(10) bond length is 2.97 Å. The Rb(2)-O(12) bond length is 3.12 Å. The Rb(2)-O(2) bond length is 3.04 Å. The Rb(2)-O(3) bond length is 3.01 Å. The Rb(2)-O(4) bond length is 2.89 Å. The Rb(2)-O(6) bond length is 3.04 Å. The Rb(2)-O(7) bond length is 3.45 Å. The Rb(2)-O(8) bond length is 3.24 Å. Mg(1) is bonded in a 5-coordinate geometry to one O(1), one O(12), one O(3), one O(5), and one O(8) atom. The Mg(1)-O(1) bond length is 2.09 Å. The Mg(1)-O(12) bond length is 2.16 Å. The Mg(1)-O(3) bond length is 1.94 Å. The Mg(1)-O(5) bond length is 2.05 Å. The Mg(1)-O(8) bond length is 2.33 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(10), one O(11), one O(2), one O(4), one O(5), and one O(8) atom to form distorted NbO6 octahedra that share corners with two equivalent Te(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. The Nb(1)-O(10) bond length is 1.99 Å. The Nb(1)-O(11) bond length is 2.35 Å. The Nb(1)-O(2) bond length is 1.94 Å. The Nb(1)-O(4) bond length is 2.03 Å. The Nb(1)-O(5) bond length is 1.84 Å. The Nb(1)-O(8) bond length is 2.08 Å. In the second Nb site, Nb(2) is bonded to one O(12), one O(2), one O(6), one O(8), and one O(9) atom to form distorted NbO5 trigonal bipyramids that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Te(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 30-44°. The Nb(2)-O(12) bond length is 2.08 Å. The Nb(2)-O(2) bond length is 1.98 Å. The Nb(2)-O(6) bond length is 1.96 Å. The Nb(2)-O(8) bond length is 1.95 Å. The Nb(2)-O(9) bond length is 1.79 Å. There are two inequivalent Te sites. In the first Te site, Te(1) is bonded to one O(1), one O(10), one O(12), one O(4), one O(6), and one O(7) atom to form TeO6 octahedra that share corners with two equivalent Nb(1)O6 octahedra and corners with two equivalent Nb(2)O5 trigonal bipyramids. The corner-sharing octahedral tilt angles range from 36-38°. The Te(1)-O(1) bond length is 1.90 Å. The Te(1)-O(10) bond length is 1.95 Å. The Te(1)-O(12) bond length is 1.99 Å. The Te(1)-O(4) bond length is 1.94 Å. The Te(1)-O(6) bond length is 1.93 Å. The Te(1)-O(7) bond length is 2.01 Å. In the second Te site, Te(2) is bonded in a 3-coordinate geometry to one O(11), one O(3), and one O(7) atom. The Te(2)-O(11) bond length is 1.89 Å. The Te(2)-O(3) bond length is 1.91 Å. The Te(2)-O(7) bond length is 2.02 Å. There are twelve inequivalent O sites. In the first O site, O(1) is bonded in an L-shaped geometry to one Mg(1) and one Te(1) atom. In the second O site, O(2) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded in a 2-coordinate geometry to one Rb(2), one Mg(1), and one Te(2) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the fifth O site, O(5) is bonded in a water-like geometry to one Mg(1) and one Nb(1) atom. In the sixth O site, O(6) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(2), and one Te(1) atom. In the seventh O site, O(7) is bonded in a 2-coordinate geometry to one Rb(1), one Rb(2), one Te(1), and one Te(2) atom. In the eighth O site, O(8) is bonded in a 3-coordinate geometry to one Rb(2), one Mg(1), one Nb(1), and one Nb(2) atom. In the ninth O site, O(9) is bonded in a distorted single-bond geometry to one Rb(1) and one Nb(2) atom. In the tenth O site, O(10) is bonded in a distorted bent 150 degrees geometry to one Rb(2), one Nb(1), and one Te(1) atom. In the eleventh O site, O(11) is bonded in a 3-coordinate geometry to one Rb(1), one Nb(1), and one Te(2) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Rb(2), one Mg(1), one Nb(2), and one Te(1) atom.