CrO2 crystallizes in the monoclinic Cm space group. There are nine inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form CrO6 octahedra that share  a cornercorner with one Cr(9)O4 tetrahedra, corners with two equivalent Cr(6)O4 tetrahedra, and edges with four equivalent Cr(2)O6 octahedra. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(9) atom to form CrO6 octahedra that share  a cornercorner with one Cr(9)O4 tetrahedra, corners with two equivalent Cr(6)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with two equivalent Cr(2)O6 octahedra. In the third Cr site, Cr(3) is bonded to one O(13), one O(6), two equivalent O(11), and two equivalent O(8) atoms to form distorted CrO6 octahedra that share  a cornercorner with one Cr(6)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, and edges with four equivalent Cr(4)O6 octahedra. In the fourth Cr site, Cr(4) is bonded to one O(11), one O(13), one O(15), one O(4), one O(6), and one O(8) atom to form distorted CrO6 octahedra that share  a cornercorner with one Cr(6)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. In the fifth Cr site, Cr(5) is bonded to one O(10), one O(15), two equivalent O(11), and two equivalent O(14) atoms to form edge-sharing CrO6 octahedra. In the sixth Cr site, Cr(6) is bonded to one O(13), one O(9), and two equivalent O(5) atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-57°. In the seventh Cr site, Cr(7) is bonded to one O(12), one O(17), two equivalent O(14), and two equivalent O(16) atoms to form CrO6 octahedra that share corners with two equivalent Cr(9)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, and edges with four equivalent Cr(8)O6 octahedra. In the eighth Cr site, Cr(8) is bonded to one O(10), one O(12), one O(14), one O(16), one O(17), and one O(18) atom to form CrO6 octahedra that share corners with two equivalent Cr(9)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, edges with two equivalent Cr(7)O6 octahedra, and edges with two equivalent Cr(8)O6 octahedra. In the ninth Cr site, Cr(9) is bonded to one O(18), one O(7), and two equivalent O(16) atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-59°. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to two equivalent Cr(2) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Cr(1) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded in a water-like geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Cr(4) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(6) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Cr(3) and two equivalent Cr(4) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal pyramidal geometry to one Cr(1), one Cr(9), and two equivalent Cr(2) atoms. In the eighth O site, O(8) is bonded in a water-like geometry to one Cr(3) and one Cr(4) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Cr(6) and two equivalent Cr(2) atoms. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Cr(5) and two equivalent Cr(8) atoms. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Cr(3), one Cr(4), and one Cr(5) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Cr(7) and two equivalent Cr(8) atoms. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Cr(3), one Cr(6), and two equivalent Cr(4) atoms. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one Cr(5), one Cr(7), and one Cr(8) atom. In the fifteenth O site, O(15) is bonded in a trigonal non-coplanar geometry to one Cr(5) and two equivalent Cr(4) atoms. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Cr(7), one Cr(8), and one Cr(9) atom. In the seventeenth O site, O(17) is bonded in a trigonal non-coplanar geometry to one Cr(7) and two equivalent Cr(8) atoms. In the eighteenth O site, O(18) is bonded in a distorted trigonal planar geometry to one Cr(9) and two equivalent Cr(8) atoms.
CrO2 crystallizes in the monoclinic Cm space group. There are nine inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(2), one O(7), two equivalent O(3), and two equivalent O(5) atoms to form CrO6 octahedra that share  a cornercorner with one Cr(9)O4 tetrahedra, corners with two equivalent Cr(6)O4 tetrahedra, and edges with four equivalent Cr(2)O6 octahedra. The Cr(1)-O(2) bond length is 1.95 Å. The Cr(1)-O(7) bond length is 2.12 Å. Both Cr(1)-O(3) bond lengths are 1.85 Å. Both Cr(1)-O(5) bond lengths are 2.06 Å. In the second Cr site, Cr(2) is bonded to one O(1), one O(2), one O(3), one O(5), one O(7), and one O(9) atom to form CrO6 octahedra that share  a cornercorner with one Cr(9)O4 tetrahedra, corners with two equivalent Cr(6)O4 tetrahedra, edges with two equivalent Cr(1)O6 octahedra, and edges with two equivalent Cr(2)O6 octahedra. The Cr(2)-O(1) bond length is 1.85 Å. The Cr(2)-O(2) bond length is 1.94 Å. The Cr(2)-O(3) bond length is 1.84 Å. The Cr(2)-O(5) bond length is 2.06 Å. The Cr(2)-O(7) bond length is 2.12 Å. The Cr(2)-O(9) bond length is 2.05 Å. In the third Cr site, Cr(3) is bonded to one O(13), one O(6), two equivalent O(11), and two equivalent O(8) atoms to form distorted CrO6 octahedra that share  a cornercorner with one Cr(6)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, and edges with four equivalent Cr(4)O6 octahedra. The Cr(3)-O(13) bond length is 2.16 Å. The Cr(3)-O(6) bond length is 1.94 Å. Both Cr(3)-O(11) bond lengths are 2.00 Å. Both Cr(3)-O(8) bond lengths are 1.83 Å. In the fourth Cr site, Cr(4) is bonded to one O(11), one O(13), one O(15), one O(4), one O(6), and one O(8) atom to form distorted CrO6 octahedra that share  a cornercorner with one Cr(6)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, edges with two equivalent Cr(3)O6 octahedra, and edges with two equivalent Cr(4)O6 octahedra. The Cr(4)-O(11) bond length is 2.00 Å. The Cr(4)-O(13) bond length is 2.15 Å. The Cr(4)-O(15) bond length is 1.99 Å. The Cr(4)-O(4) bond length is 1.83 Å. The Cr(4)-O(6) bond length is 1.94 Å. The Cr(4)-O(8) bond length is 1.84 Å. In the fifth Cr site, Cr(5) is bonded to one O(10), one O(15), two equivalent O(11), and two equivalent O(14) atoms to form edge-sharing CrO6 octahedra. The Cr(5)-O(10) bond length is 1.99 Å. The Cr(5)-O(15) bond length is 1.89 Å. Both Cr(5)-O(11) bond lengths are 1.89 Å. Both Cr(5)-O(14) bond lengths are 1.98 Å. In the sixth Cr site, Cr(6) is bonded to one O(13), one O(9), and two equivalent O(5) atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 56-57°. The Cr(6)-O(13) bond length is 1.85 Å. The Cr(6)-O(9) bond length is 1.83 Å. Both Cr(6)-O(5) bond lengths are 1.83 Å. In the seventh Cr site, Cr(7) is bonded to one O(12), one O(17), two equivalent O(14), and two equivalent O(16) atoms to form CrO6 octahedra that share corners with two equivalent Cr(9)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, and edges with four equivalent Cr(8)O6 octahedra. The Cr(7)-O(12) bond length is 1.97 Å. The Cr(7)-O(17) bond length is 1.96 Å. Both Cr(7)-O(14) bond lengths are 1.98 Å. Both Cr(7)-O(16) bond lengths are 2.01 Å. In the eighth Cr site, Cr(8) is bonded to one O(10), one O(12), one O(14), one O(16), one O(17), and one O(18) atom to form CrO6 octahedra that share corners with two equivalent Cr(9)O4 tetrahedra,  an edgeedge with one Cr(5)O6 octahedra, edges with two equivalent Cr(7)O6 octahedra, and edges with two equivalent Cr(8)O6 octahedra. The Cr(8)-O(10) bond length is 1.93 Å. The Cr(8)-O(12) bond length is 1.95 Å. The Cr(8)-O(14) bond length is 1.91 Å. The Cr(8)-O(16) bond length is 2.08 Å. The Cr(8)-O(17) bond length is 1.90 Å. The Cr(8)-O(18) bond length is 2.08 Å. In the ninth Cr site, Cr(9) is bonded to one O(18), one O(7), and two equivalent O(16) atoms to form corner-sharing CrO4 tetrahedra. The corner-sharing octahedral tilt angles range from 52-59°. The Cr(9)-O(18) bond length is 1.78 Å. The Cr(9)-O(7) bond length is 1.88 Å. Both Cr(9)-O(16) bond lengths are 1.80 Å. There are eighteen inequivalent O sites. In the first O site, O(1) is bonded in a water-like geometry to two equivalent Cr(2) atoms. In the second O site, O(2) is bonded in a distorted T-shaped geometry to one Cr(1) and two equivalent Cr(2) atoms. In the third O site, O(3) is bonded in a water-like geometry to one Cr(1) and one Cr(2) atom. In the fourth O site, O(4) is bonded in a water-like geometry to two equivalent Cr(4) atoms. In the fifth O site, O(5) is bonded in a trigonal planar geometry to one Cr(1), one Cr(2), and one Cr(6) atom. In the sixth O site, O(6) is bonded in a distorted T-shaped geometry to one Cr(3) and two equivalent Cr(4) atoms. In the seventh O site, O(7) is bonded in a distorted trigonal pyramidal geometry to one Cr(1), one Cr(9), and two equivalent Cr(2) atoms. In the eighth O site, O(8) is bonded in a water-like geometry to one Cr(3) and one Cr(4) atom. In the ninth O site, O(9) is bonded in a trigonal planar geometry to one Cr(6) and two equivalent Cr(2) atoms. In the tenth O site, O(10) is bonded in a distorted trigonal non-coplanar geometry to one Cr(5) and two equivalent Cr(8) atoms. In the eleventh O site, O(11) is bonded in a distorted trigonal non-coplanar geometry to one Cr(3), one Cr(4), and one Cr(5) atom. In the twelfth O site, O(12) is bonded in a distorted T-shaped geometry to one Cr(7) and two equivalent Cr(8) atoms. In the thirteenth O site, O(13) is bonded in a distorted rectangular see-saw-like geometry to one Cr(3), one Cr(6), and two equivalent Cr(4) atoms. In the fourteenth O site, O(14) is bonded in a distorted trigonal non-coplanar geometry to one Cr(5), one Cr(7), and one Cr(8) atom. In the fifteenth O site, O(15) is bonded in a trigonal non-coplanar geometry to one Cr(5) and two equivalent Cr(4) atoms. In the sixteenth O site, O(16) is bonded in a distorted trigonal planar geometry to one Cr(7), one Cr(8), and one Cr(9) atom. In the seventeenth O site, O(17) is bonded in a trigonal non-coplanar geometry to one Cr(7) and two equivalent Cr(8) atoms. In the eighteenth O site, O(18) is bonded in a distorted trigonal planar geometry to one Cr(9) and two equivalent Cr(8) atoms.