Mn2Mo3O8 crystallizes in the hexagonal P6_3mc space group. Mo(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O4 tetrahedra,  an edgeedge with one Mn(2)O6 octahedra, and edges with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2) and three equivalent O(3) atoms to form MnO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra and corners with nine equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-73°. In the second Mn site, Mn(2) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent Mo(1)O6 octahedra, corners with three equivalent Mn(1)O4 tetrahedra, and edges with three equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to three equivalent Mo(1) atoms. In the second O site, O(2) is bonded to three equivalent Mo(1) and one Mn(1) atom to form a mixture of distorted corner and edge-sharing OMnMo3 tetrahedra. In the third O site, O(3) is bonded to two equivalent Mo(1), one Mn(1), and one Mn(2) atom to form OMn2Mo2 tetrahedra that share  a cornercorner with one O(2)MnMo3 tetrahedra, corners with two equivalent O(3)Mn2Mo2 tetrahedra,  an edgeedge with one O(2)MnMo3 tetrahedra, and edges with two equivalent O(3)Mn2Mo2 tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Mo(1) and one Mn(2) atom.
Mn2Mo3O8 crystallizes in the hexagonal P6_3mc space group. Mo(1) is bonded to one O(1), one O(2), two equivalent O(3), and two equivalent O(4) atoms to form distorted MoO6 octahedra that share corners with two equivalent Mn(2)O6 octahedra, corners with three equivalent Mn(1)O4 tetrahedra,  an edgeedge with one Mn(2)O6 octahedra, and edges with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. The Mo(1)-O(1) bond length is 2.08 Å. The Mo(1)-O(2) bond length is 2.19 Å. Both Mo(1)-O(3) bond lengths are 2.11 Å. Both Mo(1)-O(4) bond lengths are 1.99 Å. There are two inequivalent Mn sites. In the first Mn site, Mn(1) is bonded to one O(2) and three equivalent O(3) atoms to form MnO4 tetrahedra that share corners with three equivalent Mn(2)O6 octahedra and corners with nine equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 59-73°. The Mn(1)-O(2) bond length is 2.06 Å. All Mn(1)-O(3) bond lengths are 2.07 Å. In the second Mn site, Mn(2) is bonded to three equivalent O(3) and three equivalent O(4) atoms to form MnO6 octahedra that share corners with six equivalent Mo(1)O6 octahedra, corners with three equivalent Mn(1)O4 tetrahedra, and edges with three equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 43°. All Mn(2)-O(3) bond lengths are 2.26 Å. All Mn(2)-O(4) bond lengths are 2.14 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 3-coordinate geometry to three equivalent Mo(1) atoms. In the second O site, O(2) is bonded to three equivalent Mo(1) and one Mn(1) atom to form a mixture of distorted corner and edge-sharing OMnMo3 tetrahedra. In the third O site, O(3) is bonded to two equivalent Mo(1), one Mn(1), and one Mn(2) atom to form OMn2Mo2 tetrahedra that share  a cornercorner with one O(2)MnMo3 tetrahedra, corners with two equivalent O(3)Mn2Mo2 tetrahedra,  an edgeedge with one O(2)MnMo3 tetrahedra, and edges with two equivalent O(3)Mn2Mo2 tetrahedra. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to two equivalent Mo(1) and one Mn(2) atom.