Sm3B3O7 crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one B(1), one B(3), three equivalent O(2), and three equivalent O(5) atoms to form distorted SmB2O6 hexagonal bipyramids that share  a cornercorner with one Sm(1)B2O6 hexagonal bipyramid,  a cornercorner with one Sm(3)BO7 hexagonal bipyramid, and edges with six equivalent Sm(1)B2O6 hexagonal bipyramids. In the second Sm site, Sm(2) is bonded to one B(2), one O(4), three equivalent O(3), and three equivalent O(6) atoms to form a mixture of distorted corner and edge-sharing SmBO7 hexagonal bipyramids. In the third Sm site, Sm(3) is bonded to one B(1), one O(4), three equivalent O(1), and three equivalent O(7) atoms to form distorted SmBO7 hexagonal bipyramids that share  a cornercorner with one Sm(1)B2O6 hexagonal bipyramid,  a cornercorner with one Sm(2)BO7 hexagonal bipyramid, and edges with six equivalent Sm(3)BO7 hexagonal bipyramids. There are four inequivalent B sites. In the first B site, B(1) is bonded in a bent 120 degrees geometry to one Sm(1), one Sm(3), one O(1), and one O(2) atom. In the second B site, B(2) is bonded in a bent 120 degrees geometry to two equivalent Sm(2) and two equivalent O(3) atoms. In the third B site, B(3) is bonded in a bent 120 degrees geometry to two equivalent Sm(1) and two equivalent O(5) atoms. In the fourth B site, B(4) is bonded in a distorted bent 150 degrees geometry to one O(6), one O(7), and two equivalent O(4) atoms. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a distorted single-bond geometry to three equivalent Sm(2) and one B(4) atom. In the second O site, O(7) is bonded in a distorted single-bond geometry to three equivalent Sm(3) and one B(4) atom. In the third O site, O(1) is bonded in a 1-coordinate geometry to three equivalent Sm(3) and one B(1) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Sm(1) and one B(1) atom. In the fifth O site, O(3) is bonded in a 1-coordinate geometry to three equivalent Sm(2) and one B(2) atom. In the sixth O site, O(4) is bonded in a see-saw-like geometry to one Sm(2), one Sm(3), and two equivalent B(4) atoms. In the seventh O site, O(5) is bonded in a distorted single-bond geometry to three equivalent Sm(1) and one B(3) atom.
Sm3B3O7 crystallizes in the orthorhombic Amm2 space group. There are three inequivalent Sm sites. In the first Sm site, Sm(1) is bonded to one B(1), one B(3), three equivalent O(2), and three equivalent O(5) atoms to form distorted SmB2O6 hexagonal bipyramids that share  a cornercorner with one Sm(1)B2O6 hexagonal bipyramid,  a cornercorner with one Sm(3)BO7 hexagonal bipyramid, and edges with six equivalent Sm(1)B2O6 hexagonal bipyramids. The Sm(1)-B(1) bond length is 2.74 Å. The Sm(1)-B(3) bond length is 2.71 Å. There are two shorter (2.45 Å) and one longer (2.61 Å) Sm(1)-O(2) bond length. There are two shorter (2.47 Å) and one longer (2.57 Å) Sm(1)-O(5) bond length. In the second Sm site, Sm(2) is bonded to one B(2), one O(4), three equivalent O(3), and three equivalent O(6) atoms to form a mixture of distorted corner and edge-sharing SmBO7 hexagonal bipyramids. The Sm(2)-B(2) bond length is 2.76 Å. The Sm(2)-O(4) bond length is 2.21 Å. There are two shorter (2.43 Å) and one longer (2.66 Å) Sm(2)-O(3) bond length. There are two shorter (2.51 Å) and one longer (2.52 Å) Sm(2)-O(6) bond length. In the third Sm site, Sm(3) is bonded to one B(1), one O(4), three equivalent O(1), and three equivalent O(7) atoms to form distorted SmBO7 hexagonal bipyramids that share  a cornercorner with one Sm(1)B2O6 hexagonal bipyramid,  a cornercorner with one Sm(2)BO7 hexagonal bipyramid, and edges with six equivalent Sm(3)BO7 hexagonal bipyramids. The Sm(3)-B(1) bond length is 2.73 Å. The Sm(3)-O(4) bond length is 2.21 Å. There are two shorter (2.42 Å) and one longer (2.65 Å) Sm(3)-O(1) bond length. There is one shorter (2.50 Å) and two longer (2.51 Å) Sm(3)-O(7) bond lengths. There are four inequivalent B sites. In the first B site, B(1) is bonded in a bent 120 degrees geometry to one Sm(1), one Sm(3), one O(1), and one O(2) atom. The B(1)-O(1) bond length is 1.39 Å. The B(1)-O(2) bond length is 1.39 Å. In the second B site, B(2) is bonded in a bent 120 degrees geometry to two equivalent Sm(2) and two equivalent O(3) atoms. Both B(2)-O(3) bond lengths are 1.39 Å. In the third B site, B(3) is bonded in a bent 120 degrees geometry to two equivalent Sm(1) and two equivalent O(5) atoms. Both B(3)-O(5) bond lengths are 1.39 Å. In the fourth B site, B(4) is bonded in a distorted bent 150 degrees geometry to one O(6), one O(7), and two equivalent O(4) atoms. The B(4)-O(6) bond length is 1.32 Å. The B(4)-O(7) bond length is 1.33 Å. Both B(4)-O(4) bond lengths are 2.14 Å. There are seven inequivalent O sites. In the first O site, O(6) is bonded in a distorted single-bond geometry to three equivalent Sm(2) and one B(4) atom. In the second O site, O(7) is bonded in a distorted single-bond geometry to three equivalent Sm(3) and one B(4) atom. In the third O site, O(1) is bonded in a 1-coordinate geometry to three equivalent Sm(3) and one B(1) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Sm(1) and one B(1) atom. In the fifth O site, O(3) is bonded in a 1-coordinate geometry to three equivalent Sm(2) and one B(2) atom. In the sixth O site, O(4) is bonded in a see-saw-like geometry to one Sm(2), one Sm(3), and two equivalent B(4) atoms. In the seventh O site, O(5) is bonded in a distorted single-bond geometry to three equivalent Sm(1) and one B(3) atom.