Mo4O9 crystallizes in the tetragonal P4/m space group. Mo(1) is bonded to one O(1), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. There are three inequivalent O sites. In the first O site, O(3) is bonded in a T-shaped geometry to three equivalent Mo(1) atoms. In the second O site, O(1) is bonded in a square co-planar geometry to four equivalent Mo(1) atoms. In the third O site, O(2) is bonded in a linear geometry to two equivalent Mo(1) atoms.
Mo4O9 crystallizes in the tetragonal P4/m space group. Mo(1) is bonded to one O(1), two equivalent O(2), and three equivalent O(3) atoms to form a mixture of corner and edge-sharing MoO6 octahedra. The corner-sharing octahedral tilt angles range from 0-21°. The Mo(1)-O(1) bond length is 2.24 Å. Both Mo(1)-O(2) bond lengths are 1.93 Å. There are two shorter (2.06 Å) and one longer (2.07 Å) Mo(1)-O(3) bond length. There are three inequivalent O sites. In the first O site, O(3) is bonded in a T-shaped geometry to three equivalent Mo(1) atoms. In the second O site, O(1) is bonded in a square co-planar geometry to four equivalent Mo(1) atoms. In the third O site, O(2) is bonded in a linear geometry to two equivalent Mo(1) atoms.