FeSn3(PO4)6 crystallizes in the trigonal R3 space group. Fe(1) is bonded to three equivalent O(4) and three equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the second Sn site, Sn(2) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. In the third Sn site, Sn(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Sn(2)O6 octahedra, and  a cornercorner with one Sn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-35°. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Sn(2)O6 octahedra, and  a cornercorner with one Sn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-33°. There are eight inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the second O site, O(3) is bonded in a bent 150 degrees geometry to one Sn(2) and one P(1) atom. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(5) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(2) atom. In the fifth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(7) is bonded in a bent 150 degrees geometry to one Sn(3) and one P(2) atom. In the seventh O site, O(8) is bonded in a bent 150 degrees geometry to one Sn(3) and one P(1) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one Sn(2) and one P(2) atom.
FeSn3(PO4)6 crystallizes in the trigonal R3 space group. Fe(1) is bonded to three equivalent O(4) and three equivalent O(6) atoms to form FeO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Fe(1)-O(4) bond lengths are 1.99 Å. All Fe(1)-O(6) bond lengths are 1.98 Å. There are three inequivalent Sn sites. In the first Sn site, Sn(1) is bonded to three equivalent O(2) and three equivalent O(5) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Sn(1)-O(2) bond lengths are 2.04 Å. All Sn(1)-O(5) bond lengths are 2.04 Å. In the second Sn site, Sn(2) is bonded to three equivalent O(1) and three equivalent O(3) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Sn(2)-O(1) bond lengths are 2.05 Å. All Sn(2)-O(3) bond lengths are 2.05 Å. In the third Sn site, Sn(3) is bonded to three equivalent O(7) and three equivalent O(8) atoms to form SnO6 octahedra that share corners with three equivalent P(1)O4 tetrahedra and corners with three equivalent P(2)O4 tetrahedra. All Sn(3)-O(7) bond lengths are 2.04 Å. All Sn(3)-O(8) bond lengths are 2.04 Å. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(2), one O(3), one O(4), and one O(8) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Sn(2)O6 octahedra, and  a cornercorner with one Sn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 24-35°. The P(1)-O(2) bond length is 1.55 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.54 Å. The P(1)-O(8) bond length is 1.54 Å. In the second P site, P(2) is bonded to one O(1), one O(5), one O(6), and one O(7) atom to form PO4 tetrahedra that share  a cornercorner with one Fe(1)O6 octahedra,  a cornercorner with one Sn(1)O6 octahedra,  a cornercorner with one Sn(2)O6 octahedra, and  a cornercorner with one Sn(3)O6 octahedra. The corner-sharing octahedral tilt angles range from 27-33°. The P(2)-O(1) bond length is 1.54 Å. The P(2)-O(5) bond length is 1.54 Å. The P(2)-O(6) bond length is 1.54 Å. The P(2)-O(7) bond length is 1.55 Å. There are eight inequivalent O sites. In the first O site, O(2) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(1) atom. In the second O site, O(3) is bonded in a bent 150 degrees geometry to one Sn(2) and one P(1) atom. In the third O site, O(4) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(1) atom. In the fourth O site, O(5) is bonded in a bent 150 degrees geometry to one Sn(1) and one P(2) atom. In the fifth O site, O(6) is bonded in a bent 150 degrees geometry to one Fe(1) and one P(2) atom. In the sixth O site, O(7) is bonded in a bent 150 degrees geometry to one Sn(3) and one P(2) atom. In the seventh O site, O(8) is bonded in a bent 150 degrees geometry to one Sn(3) and one P(1) atom. In the eighth O site, O(1) is bonded in a bent 150 degrees geometry to one Sn(2) and one P(2) atom.