Cr3O8 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing CrO6 octahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-41°. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Cr(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom.
Cr3O8 crystallizes in the monoclinic P2_1/c space group. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms to form corner-sharing CrO6 octahedra. Both Cr(1)-O(2) bond lengths are 1.95 Å. Both Cr(1)-O(3) bond lengths are 1.95 Å. Both Cr(1)-O(4) bond lengths are 1.89 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 38-41°. The Cr(2)-O(1) bond length is 1.58 Å. The Cr(2)-O(2) bond length is 1.70 Å. The Cr(2)-O(3) bond length is 1.69 Å. The Cr(2)-O(4) bond length is 1.72 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a single-bond geometry to one Cr(2) atom. In the second O site, O(2) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the third O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(1) and one Cr(2) atom.