Cr2AlO4 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. In the second Cr site, Cr(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. In the third Cr site, Cr(3) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. In the fourth Cr site, Cr(4) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. Al(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing AlO6 pentagonal pyramids. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Cr(2), one Cr(4), and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Cr2 tetrahedra. In the second O site, O(2) is bonded to one Cr(1), one Cr(3), and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Cr2 trigonal pyramids. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Cr(1), one Cr(4), and one Al(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one Al(1) atom.
Cr2AlO4 crystallizes in the triclinic P-1 space group. There are four inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted square co-planar geometry to two equivalent O(2) and two equivalent O(3) atoms. Both Cr(1)-O(2) bond lengths are 1.99 Å. Both Cr(1)-O(3) bond lengths are 1.97 Å. In the second Cr site, Cr(2) is bonded in a distorted square co-planar geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Cr(2)-O(1) bond lengths are 1.99 Å. Both Cr(2)-O(4) bond lengths are 1.96 Å. In the third Cr site, Cr(3) is bonded in a square co-planar geometry to two equivalent O(2) and two equivalent O(4) atoms. Both Cr(3)-O(2) bond lengths are 2.08 Å. Both Cr(3)-O(4) bond lengths are 1.93 Å. In the fourth Cr site, Cr(4) is bonded in a square co-planar geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Cr(4)-O(1) bond lengths are 2.09 Å. Both Cr(4)-O(3) bond lengths are 1.95 Å. Al(1) is bonded to one O(3), one O(4), two equivalent O(1), and two equivalent O(2) atoms to form distorted edge-sharing AlO6 pentagonal pyramids. The Al(1)-O(3) bond length is 1.92 Å. The Al(1)-O(4) bond length is 1.94 Å. There is one shorter (1.99 Å) and one longer (2.03 Å) Al(1)-O(1) bond length. There is one shorter (1.98 Å) and one longer (2.07 Å) Al(1)-O(2) bond length. There are four inequivalent O sites. In the first O site, O(1) is bonded to one Cr(2), one Cr(4), and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Cr2 tetrahedra. In the second O site, O(2) is bonded to one Cr(1), one Cr(3), and two equivalent Al(1) atoms to form a mixture of distorted edge and corner-sharing OAl2Cr2 trigonal pyramids. In the third O site, O(3) is bonded in a trigonal non-coplanar geometry to one Cr(1), one Cr(4), and one Al(1) atom. In the fourth O site, O(4) is bonded in a trigonal non-coplanar geometry to one Cr(2), one Cr(3), and one Al(1) atom.