Mn3(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and two equivalent O(2) atoms. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a cornercorner with one Mn(3)O5 trigonal bipyramid. In the third Mn site, Mn(3) is bonded to one O(7), two equivalent O(4), and two equivalent O(8) atoms to form distorted MnO5 trigonal bipyramids that share  a cornercorner with one Mn(2)O5 square pyramid, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Mn(3)O5 trigonal bipyramids. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Mn(2)O5 square pyramids and corners with two equivalent Mn(3)O5 trigonal bipyramids. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Mn(2)O5 square pyramids and corners with three equivalent Mn(3)O5 trigonal bipyramids. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal planar geometry to one Mn(2), one Mn(3), and one P(2) atom. In the second O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Mn(3) and one P(2) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the fifth O site, O(3) is bonded in a 2-coordinate geometry to one Mn(1), one Mn(2), and one P(1) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Mn(3) and one P(1) atom. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom. In the eighth O site, O(6) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom.
Mn3(PO4)2 crystallizes in the monoclinic P2_1/c space group. There are three inequivalent Mn sites. In the first Mn site, Mn(1) is bonded in a 6-coordinate geometry to one O(1), one O(3), one O(5), one O(6), and two equivalent O(2) atoms. The Mn(1)-O(1) bond length is 2.10 Å. The Mn(1)-O(3) bond length is 2.73 Å. The Mn(1)-O(5) bond length is 2.26 Å. The Mn(1)-O(6) bond length is 2.37 Å. There is one shorter (2.13 Å) and one longer (2.25 Å) Mn(1)-O(2) bond length. In the second Mn site, Mn(2) is bonded to one O(1), one O(3), one O(5), one O(6), and one O(7) atom to form distorted MnO5 square pyramids that share corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and  a cornercorner with one Mn(3)O5 trigonal bipyramid. The Mn(2)-O(1) bond length is 2.42 Å. The Mn(2)-O(3) bond length is 2.10 Å. The Mn(2)-O(5) bond length is 2.04 Å. The Mn(2)-O(6) bond length is 2.04 Å. The Mn(2)-O(7) bond length is 2.36 Å. In the third Mn site, Mn(3) is bonded to one O(7), two equivalent O(4), and two equivalent O(8) atoms to form distorted MnO5 trigonal bipyramids that share  a cornercorner with one Mn(2)O5 square pyramid, corners with two equivalent P(1)O4 tetrahedra, corners with three equivalent P(2)O4 tetrahedra, and edges with two equivalent Mn(3)O5 trigonal bipyramids. The Mn(3)-O(7) bond length is 2.15 Å. There is one shorter (2.11 Å) and one longer (2.22 Å) Mn(3)-O(4) bond length. There is one shorter (2.15 Å) and one longer (2.29 Å) Mn(3)-O(8) bond length. There are two inequivalent P sites. In the first P site, P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form PO4 tetrahedra that share corners with two equivalent Mn(2)O5 square pyramids and corners with two equivalent Mn(3)O5 trigonal bipyramids. The P(1)-O(1) bond length is 1.56 Å. The P(1)-O(2) bond length is 1.57 Å. The P(1)-O(3) bond length is 1.54 Å. The P(1)-O(4) bond length is 1.56 Å. In the second P site, P(2) is bonded to one O(5), one O(6), one O(7), and one O(8) atom to form PO4 tetrahedra that share corners with three equivalent Mn(2)O5 square pyramids and corners with three equivalent Mn(3)O5 trigonal bipyramids. The P(2)-O(5) bond length is 1.56 Å. The P(2)-O(6) bond length is 1.55 Å. The P(2)-O(7) bond length is 1.56 Å. The P(2)-O(8) bond length is 1.55 Å. There are eight inequivalent O sites. In the first O site, O(7) is bonded in a distorted trigonal planar geometry to one Mn(2), one Mn(3), and one P(2) atom. In the second O site, O(8) is bonded in a distorted trigonal planar geometry to two equivalent Mn(3) and one P(2) atom. In the third O site, O(1) is bonded in a distorted trigonal planar geometry to one Mn(1), one Mn(2), and one P(1) atom. In the fourth O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Mn(1) and one P(1) atom. In the fifth O site, O(3) is bonded in a 2-coordinate geometry to one Mn(1), one Mn(2), and one P(1) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Mn(3) and one P(1) atom. In the seventh O site, O(5) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom. In the eighth O site, O(6) is bonded in a 3-coordinate geometry to one Mn(1), one Mn(2), and one P(2) atom.