Sc3NbO7 crystallizes in the monoclinic P2/c space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted corner-sharing ScO6 octahedra. The corner-sharing octahedral tilt angles are 68°. In the second Sc site, Sc(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Nb(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form OSc4 tetrahedra that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids, edges with two equivalent O(4)Sc3Nb tetrahedra, and edges with two equivalent O(2)Sc3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Sc(1), two equivalent Sc(2), and one Nb(1) atom to form distorted OSc3Nb trigonal pyramids that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids,  an edgeedge with one O(1)Sc4 tetrahedra, and edges with two equivalent O(4)Sc3Nb tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sc(2) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to one Sc(1), two equivalent Sc(2), and one Nb(1) atom to form distorted OSc3Nb tetrahedra that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids,  an edgeedge with one O(1)Sc4 tetrahedra, and edges with two equivalent O(2)Sc3Nb trigonal pyramids.
Sc3NbO7 crystallizes in the monoclinic P2/c space group. There are two inequivalent Sc sites. In the first Sc site, Sc(1) is bonded to two equivalent O(1), two equivalent O(2), and two equivalent O(4) atoms to form distorted corner-sharing ScO6 octahedra. The corner-sharing octahedral tilt angles are 68°. Both Sc(1)-O(1) bond lengths are 2.16 Å. Both Sc(1)-O(2) bond lengths are 2.09 Å. Both Sc(1)-O(4) bond lengths are 2.14 Å. In the second Sc site, Sc(2) is bonded in a 7-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. The Sc(2)-O(1) bond length is 2.08 Å. There is one shorter (2.05 Å) and one longer (2.42 Å) Sc(2)-O(2) bond length. There is one shorter (1.94 Å) and one longer (2.58 Å) Sc(2)-O(3) bond length. There is one shorter (2.07 Å) and one longer (2.46 Å) Sc(2)-O(4) bond length. Nb(1) is bonded in a distorted body-centered cubic geometry to two equivalent O(2), two equivalent O(4), and four equivalent O(3) atoms. Both Nb(1)-O(2) bond lengths are 2.25 Å. Both Nb(1)-O(4) bond lengths are 2.12 Å. There are two shorter (2.09 Å) and two longer (2.21 Å) Nb(1)-O(3) bond lengths. There are four inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sc(1) and two equivalent Sc(2) atoms to form OSc4 tetrahedra that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids, edges with two equivalent O(4)Sc3Nb tetrahedra, and edges with two equivalent O(2)Sc3Nb trigonal pyramids. In the second O site, O(2) is bonded to one Sc(1), two equivalent Sc(2), and one Nb(1) atom to form distorted OSc3Nb trigonal pyramids that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids,  an edgeedge with one O(1)Sc4 tetrahedra, and edges with two equivalent O(4)Sc3Nb tetrahedra. In the third O site, O(3) is bonded in a 4-coordinate geometry to two equivalent Sc(2) and two equivalent Nb(1) atoms. In the fourth O site, O(4) is bonded to one Sc(1), two equivalent Sc(2), and one Nb(1) atom to form distorted OSc3Nb tetrahedra that share corners with two equivalent O(1)Sc4 tetrahedra, corners with four equivalent O(4)Sc3Nb tetrahedra, corners with four equivalent O(2)Sc3Nb trigonal pyramids,  an edgeedge with one O(1)Sc4 tetrahedra, and edges with two equivalent O(2)Sc3Nb trigonal pyramids.