MgSc2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(5), and one O(8) atom. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and one O(7) atom. In the second Sc site, Sc(2) is bonded to one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted ScO5 trigonal bipyramids that share corners with three equivalent Nb(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-62°. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted NbO6 octahedra that share corners with three equivalent Sc(2)O5 trigonal bipyramids and edges with two equivalent Nb(2)O6 octahedra. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form NbO6 octahedra that share corners with three equivalent Sc(2)O5 trigonal bipyramids and edges with two equivalent Nb(1)O6 octahedra. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Sc(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sc(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Sc(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted corner and edge-sharing OMgScNb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Sc(2), and one Nb(2) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Sc(1), one Sc(2), and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OMgSc2Nb tetrahedra. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sc(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Sc(1), one Sc(2), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Sc(2), and one Nb(2) atom.
MgSc2Nb2O8 crystallizes in the triclinic P1 space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(3), one O(4), one O(5), and one O(8) atom. The Mg(1)-O(3) bond length is 1.95 Å. The Mg(1)-O(4) bond length is 2.00 Å. The Mg(1)-O(5) bond length is 1.97 Å. The Mg(1)-O(8) bond length is 1.97 Å. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded in a 5-coordinate geometry to one O(1), one O(2), one O(3), one O(5), and one O(7) atom. The Sc(1)-O(1) bond length is 2.10 Å. The Sc(1)-O(2) bond length is 2.07 Å. The Sc(1)-O(3) bond length is 2.12 Å. The Sc(1)-O(5) bond length is 2.03 Å. The Sc(1)-O(7) bond length is 2.19 Å. In the second Sc site, Sc(2) is bonded to one O(4), one O(5), one O(6), one O(7), and one O(8) atom to form distorted ScO5 trigonal bipyramids that share corners with three equivalent Nb(1)O6 octahedra and corners with three equivalent Nb(2)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-62°. The Sc(2)-O(4) bond length is 2.01 Å. The Sc(2)-O(5) bond length is 2.27 Å. The Sc(2)-O(6) bond length is 2.10 Å. The Sc(2)-O(7) bond length is 2.07 Å. The Sc(2)-O(8) bond length is 2.07 Å. There are two inequivalent Nb sites. In the first Nb site, Nb(1) is bonded to one O(1), one O(2), one O(3), one O(5), one O(6), and one O(7) atom to form distorted NbO6 octahedra that share corners with three equivalent Sc(2)O5 trigonal bipyramids and edges with two equivalent Nb(2)O6 octahedra. The Nb(1)-O(1) bond length is 2.03 Å. The Nb(1)-O(2) bond length is 2.34 Å. The Nb(1)-O(3) bond length is 2.07 Å. The Nb(1)-O(5) bond length is 2.18 Å. The Nb(1)-O(6) bond length is 2.12 Å. The Nb(1)-O(7) bond length is 1.94 Å. In the second Nb site, Nb(2) is bonded to one O(1), one O(2), one O(3), one O(4), one O(6), and one O(8) atom to form NbO6 octahedra that share corners with three equivalent Sc(2)O5 trigonal bipyramids and edges with two equivalent Nb(1)O6 octahedra. The Nb(2)-O(1) bond length is 2.12 Å. The Nb(2)-O(2) bond length is 1.98 Å. The Nb(2)-O(3) bond length is 2.26 Å. The Nb(2)-O(4) bond length is 2.14 Å. The Nb(2)-O(6) bond length is 2.04 Å. The Nb(2)-O(8) bond length is 2.04 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded in a T-shaped geometry to one Sc(1), one Nb(1), and one Nb(2) atom. In the second O site, O(2) is bonded in a 3-coordinate geometry to one Sc(1), one Nb(1), and one Nb(2) atom. In the third O site, O(3) is bonded to one Mg(1), one Sc(1), one Nb(1), and one Nb(2) atom to form a mixture of distorted corner and edge-sharing OMgScNb2 trigonal pyramids. In the fourth O site, O(4) is bonded in a distorted T-shaped geometry to one Mg(1), one Sc(2), and one Nb(2) atom. In the fifth O site, O(5) is bonded to one Mg(1), one Sc(1), one Sc(2), and one Nb(1) atom to form a mixture of distorted corner and edge-sharing OMgSc2Nb tetrahedra. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to one Sc(2), one Nb(1), and one Nb(2) atom. In the seventh O site, O(7) is bonded in a distorted trigonal non-coplanar geometry to one Sc(1), one Sc(2), and one Nb(1) atom. In the eighth O site, O(8) is bonded in a T-shaped geometry to one Mg(1), one Sc(2), and one Nb(2) atom.