Fe2Mo3O8 is beta indium sulfide-derived structured and crystallizes in the hexagonal P6_3mc space group. Mo(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MoO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O4 trigonal pyramids,  an edgeedge with one Fe(2)O6 octahedra, and edges with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4) and three equivalent O(2) atoms to form FeO4 trigonal pyramids that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-64°. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form FeO6 octahedra that share corners with six equivalent Mo(1)O6 octahedra, corners with three equivalent Fe(1)O4 trigonal pyramids, and edges with three equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mo(1) and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mo(1), one Fe(1), and one Fe(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to three equivalent Mo(1) and one Fe(1) atom.
Fe2Mo3O8 is beta indium sulfide-derived structured and crystallizes in the hexagonal P6_3mc space group. Mo(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form MoO6 octahedra that share corners with two equivalent Fe(2)O6 octahedra, corners with three equivalent Fe(1)O4 trigonal pyramids,  an edgeedge with one Fe(2)O6 octahedra, and edges with four equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. The Mo(1)-O(3) bond length is 2.06 Å. The Mo(1)-O(4) bond length is 2.18 Å. Both Mo(1)-O(1) bond lengths are 2.10 Å. Both Mo(1)-O(2) bond lengths are 2.20 Å. There are two inequivalent Fe sites. In the first Fe site, Fe(1) is bonded to one O(4) and three equivalent O(2) atoms to form FeO4 trigonal pyramids that share corners with three equivalent Fe(2)O6 octahedra and corners with nine equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 50-64°. The Fe(1)-O(4) bond length is 1.93 Å. All Fe(1)-O(2) bond lengths are 1.98 Å. In the second Fe site, Fe(2) is bonded to three equivalent O(1) and three equivalent O(2) atoms to form FeO6 octahedra that share corners with six equivalent Mo(1)O6 octahedra, corners with three equivalent Fe(1)O4 trigonal pyramids, and edges with three equivalent Mo(1)O6 octahedra. The corner-sharing octahedral tilt angles are 50°. All Fe(2)-O(1) bond lengths are 1.98 Å. All Fe(2)-O(2) bond lengths are 2.24 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Mo(1) and one Fe(2) atom. In the second O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to two equivalent Mo(1), one Fe(1), and one Fe(2) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to three equivalent Mo(1) atoms. In the fourth O site, O(4) is bonded in a distorted trigonal pyramidal geometry to three equivalent Mo(1) and one Fe(1) atom.