KCr2FeO9 crystallizes in the monoclinic P2_1/m space group. K(1) is bonded in a 10-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), two equivalent O(6), and three equivalent O(5) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 36°. In the second Cr site, Cr(2) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form CrO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-44°. Fe(1) is bonded to one O(4), one O(7), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Cr(1)O4 tetrahedra and corners with three equivalent Cr(2)O4 tetrahedra. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to two equivalent K(1) and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Cr(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(2) and one Fe(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Cr(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one K(1), one Cr(2), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one Fe(1) atom.
KCr2FeO9 crystallizes in the monoclinic P2_1/m space group. K(1) is bonded in a 10-coordinate geometry to one O(1), two equivalent O(2), two equivalent O(3), two equivalent O(6), and three equivalent O(5) atoms. The K(1)-O(1) bond length is 2.75 Å. Both K(1)-O(2) bond lengths are 3.22 Å. Both K(1)-O(3) bond lengths are 2.90 Å. Both K(1)-O(6) bond lengths are 2.89 Å. There is one shorter (2.87 Å) and two longer (3.19 Å) K(1)-O(5) bond lengths. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form CrO4 tetrahedra that share corners with two equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles are 36°. The Cr(1)-O(1) bond length is 1.63 Å. The Cr(1)-O(2) bond length is 1.62 Å. Both Cr(1)-O(3) bond lengths are 1.71 Å. In the second Cr site, Cr(2) is bonded to one O(4), one O(5), and two equivalent O(6) atoms to form CrO4 tetrahedra that share corners with three equivalent Fe(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 32-44°. The Cr(2)-O(4) bond length is 1.66 Å. The Cr(2)-O(5) bond length is 1.62 Å. Both Cr(2)-O(6) bond lengths are 1.69 Å. Fe(1) is bonded to one O(4), one O(7), two equivalent O(3), and two equivalent O(6) atoms to form FeO6 octahedra that share corners with two equivalent Cr(1)O4 tetrahedra and corners with three equivalent Cr(2)O4 tetrahedra. The Fe(1)-O(4) bond length is 2.02 Å. The Fe(1)-O(7) bond length is 2.10 Å. Both Fe(1)-O(3) bond lengths are 1.97 Å. Both Fe(1)-O(6) bond lengths are 2.02 Å. There are seven inequivalent O sites. In the first O site, O(1) is bonded in a distorted single-bond geometry to one K(1) and one Cr(1) atom. In the second O site, O(2) is bonded in a single-bond geometry to two equivalent K(1) and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted bent 150 degrees geometry to one K(1), one Cr(1), and one Fe(1) atom. In the fourth O site, O(4) is bonded in a bent 150 degrees geometry to one Cr(2) and one Fe(1) atom. In the fifth O site, O(5) is bonded in a distorted single-bond geometry to three equivalent K(1) and one Cr(2) atom. In the sixth O site, O(6) is bonded in a 2-coordinate geometry to one K(1), one Cr(2), and one Fe(1) atom. In the seventh O site, O(7) is bonded in a single-bond geometry to one Fe(1) atom.