Sr2ScFeAsO3 crystallizes in the tetragonal P4/nmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(1) atoms. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. Sc(1) is bonded to one As(1), one O(2), and four equivalent O(1) atoms to form ScAsO5 square pyramids that share corners with four equivalent Sc(1)AsO5 square pyramids and corners with four equivalent Fe(1)As4 tetrahedra. Fe(1) is bonded to four equivalent As(1) atoms to form distorted FeAs4 tetrahedra that share corners with four equivalent Sc(1)AsO5 square pyramids, corners with four equivalent Fe(1)As4 tetrahedra, and edges with four equivalent Fe(1)As4 tetrahedra. As(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Sc(1), and four equivalent Fe(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Sc(1) atoms to form distorted OSr4Sc2 octahedra that share corners with two equivalent O(1)Sr4Sc2 octahedra, corners with six equivalent O(2)Sr5Sc octahedra, edges with two equivalent O(1)Sr4Sc2 octahedra, faces with two equivalent O(2)Sr5Sc octahedra, and faces with four equivalent O(1)Sr4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 17-55°. In the second O site, O(2) is bonded to five equivalent Sr(2) and one Sc(1) atom to form distorted OSr5Sc octahedra that share corners with four equivalent O(2)Sr5Sc octahedra, corners with twelve equivalent O(1)Sr4Sc2 octahedra, edges with eight equivalent O(2)Sr5Sc octahedra, and faces with four equivalent O(1)Sr4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 12-55°.
Sr2ScFeAsO3 crystallizes in the tetragonal P4/nmm space group. There are two inequivalent Sr sites. In the first Sr site, Sr(1) is bonded in a 4-coordinate geometry to four equivalent As(1) and four equivalent O(1) atoms. All Sr(1)-As(1) bond lengths are 3.34 Å. All Sr(1)-O(1) bond lengths are 2.58 Å. In the second Sr site, Sr(2) is bonded in a 9-coordinate geometry to four equivalent O(1) and five equivalent O(2) atoms. All Sr(2)-O(1) bond lengths are 2.88 Å. There is one shorter (2.43 Å) and four longer (2.93 Å) Sr(2)-O(2) bond lengths. Sc(1) is bonded to one As(1), one O(2), and four equivalent O(1) atoms to form ScAsO5 square pyramids that share corners with four equivalent Sc(1)AsO5 square pyramids and corners with four equivalent Fe(1)As4 tetrahedra. The Sc(1)-As(1) bond length is 3.49 Å. The Sc(1)-O(2) bond length is 2.00 Å. All Sc(1)-O(1) bond lengths are 2.09 Å. Fe(1) is bonded to four equivalent As(1) atoms to form distorted FeAs4 tetrahedra that share corners with four equivalent Sc(1)AsO5 square pyramids, corners with four equivalent Fe(1)As4 tetrahedra, and edges with four equivalent Fe(1)As4 tetrahedra. All Fe(1)-As(1) bond lengths are 2.62 Å. As(1) is bonded in a 9-coordinate geometry to four equivalent Sr(1), one Sc(1), and four equivalent Fe(1) atoms. There are two inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Sr(1), two equivalent Sr(2), and two equivalent Sc(1) atoms to form distorted OSr4Sc2 octahedra that share corners with two equivalent O(1)Sr4Sc2 octahedra, corners with six equivalent O(2)Sr5Sc octahedra, edges with two equivalent O(1)Sr4Sc2 octahedra, faces with two equivalent O(2)Sr5Sc octahedra, and faces with four equivalent O(1)Sr4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 17-55°. In the second O site, O(2) is bonded to five equivalent Sr(2) and one Sc(1) atom to form distorted OSr5Sc octahedra that share corners with four equivalent O(2)Sr5Sc octahedra, corners with twelve equivalent O(1)Sr4Sc2 octahedra, edges with eight equivalent O(2)Sr5Sc octahedra, and faces with four equivalent O(1)Sr4Sc2 octahedra. The corner-sharing octahedral tilt angles range from 12-55°.