Sr2SmCu2GaO7 crystallizes in the orthorhombic Ima2 space group. Sr(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. Sm(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. Cu(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 square pyramids that share corners with four equivalent Cu(1)O5 square pyramids and  a cornercorner with one Ga(1)O4 tetrahedra. Ga(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form GaO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Ga(1)O4 tetrahedra. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to four equivalent Sr(1), one Cu(1), and one Ga(1) atom. In the second O site, O(1) is bonded to two equivalent Sr(1) and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, and corners with two equivalent O(1)Sr2Ga2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-70°. In the third O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sm(1), and two equivalent Cu(1) atoms to form distorted OSr2Sm2Cu2 octahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, corners with two equivalent O(1)Sr2Ga2 tetrahedra, edges with three equivalent O(3)Sr2Sm2Cu2 octahedra, faces with two equivalent O(2)Sr2Sm2Cu2 octahedra, and faces with two equivalent O(3)Sr2Sm2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the fourth O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sm(1), and two equivalent Cu(1) atoms to form distorted OSr2Sm2Cu2 octahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, corners with two equivalent O(1)Sr2Ga2 tetrahedra, edges with three equivalent O(2)Sr2Sm2Cu2 octahedra, faces with two equivalent O(2)Sr2Sm2Cu2 octahedra, and faces with two equivalent O(3)Sr2Sm2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°.
Sr2SmCu2GaO7 crystallizes in the orthorhombic Ima2 space group. Sr(1) is bonded in a 9-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), and four equivalent O(4) atoms. The Sr(1)-O(1) bond length is 2.48 Å. There is one shorter (2.83 Å) and one longer (2.84 Å) Sr(1)-O(2) bond length. Both Sr(1)-O(3) bond lengths are 2.79 Å. There are a spread of Sr(1)-O(4) bond distances ranging from 2.49-3.22 Å. Sm(1) is bonded in a body-centered cubic geometry to four equivalent O(2) and four equivalent O(3) atoms. All Sm(1)-O(2) bond lengths are 2.49 Å. There are two shorter (2.44 Å) and two longer (2.45 Å) Sm(1)-O(3) bond lengths. Cu(1) is bonded to one O(4), two equivalent O(2), and two equivalent O(3) atoms to form distorted CuO5 square pyramids that share corners with four equivalent Cu(1)O5 square pyramids and  a cornercorner with one Ga(1)O4 tetrahedra. The Cu(1)-O(4) bond length is 2.42 Å. Both Cu(1)-O(2) bond lengths are 1.95 Å. Both Cu(1)-O(3) bond lengths are 1.97 Å. Ga(1) is bonded to two equivalent O(1) and two equivalent O(4) atoms to form GaO4 tetrahedra that share corners with two equivalent Cu(1)O5 square pyramids and corners with two equivalent Ga(1)O4 tetrahedra. Both Ga(1)-O(1) bond lengths are 1.92 Å. Both Ga(1)-O(4) bond lengths are 1.85 Å. There are four inequivalent O sites. In the first O site, O(4) is bonded in a 4-coordinate geometry to four equivalent Sr(1), one Cu(1), and one Ga(1) atom. In the second O site, O(1) is bonded to two equivalent Sr(1) and two equivalent Ga(1) atoms to form distorted OSr2Ga2 tetrahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, and corners with two equivalent O(1)Sr2Ga2 tetrahedra. The corner-sharing octahedral tilt angles range from 19-70°. In the third O site, O(2) is bonded to two equivalent Sr(1), two equivalent Sm(1), and two equivalent Cu(1) atoms to form distorted OSr2Sm2Cu2 octahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, corners with two equivalent O(1)Sr2Ga2 tetrahedra, edges with three equivalent O(3)Sr2Sm2Cu2 octahedra, faces with two equivalent O(2)Sr2Sm2Cu2 octahedra, and faces with two equivalent O(3)Sr2Sm2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°. In the fourth O site, O(3) is bonded to two equivalent Sr(1), two equivalent Sm(1), and two equivalent Cu(1) atoms to form distorted OSr2Sm2Cu2 octahedra that share corners with four equivalent O(2)Sr2Sm2Cu2 octahedra, corners with four equivalent O(3)Sr2Sm2Cu2 octahedra, corners with two equivalent O(1)Sr2Ga2 tetrahedra, edges with three equivalent O(2)Sr2Sm2Cu2 octahedra, faces with two equivalent O(2)Sr2Sm2Cu2 octahedra, and faces with two equivalent O(3)Sr2Sm2Cu2 octahedra. The corner-sharing octahedral tilt angles range from 0-69°.