MgCrFe(BiO3)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with three equivalent Bi(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. Cr(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Bi(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 79-82°. Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted BiO6 octahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with three equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom.
MgCrFe(BiO3)2 crystallizes in the triclinic P1 space group. Mg(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form MgO6 octahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with three equivalent Bi(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. The Mg(1)-O(1) bond length is 2.31 Å. The Mg(1)-O(2) bond length is 2.19 Å. The Mg(1)-O(3) bond length is 2.06 Å. The Mg(1)-O(4) bond length is 2.14 Å. The Mg(1)-O(5) bond length is 2.28 Å. The Mg(1)-O(6) bond length is 2.06 Å. Cr(1) is bonded to one O(1), one O(2), one O(3), one O(5), and one O(6) atom to form distorted CrO5 trigonal bipyramids that share  a cornercorner with one Mg(1)O6 octahedra,  a cornercorner with one Bi(1)O6 octahedra, edges with two equivalent Mg(1)O6 octahedra, and edges with two equivalent Bi(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 79-82°. The Cr(1)-O(1) bond length is 2.43 Å. The Cr(1)-O(2) bond length is 2.16 Å. The Cr(1)-O(3) bond length is 2.16 Å. The Cr(1)-O(5) bond length is 2.10 Å. The Cr(1)-O(6) bond length is 2.17 Å. Fe(1) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Fe(1)-O(1) bond length is 2.02 Å. The Fe(1)-O(2) bond length is 2.38 Å. The Fe(1)-O(3) bond length is 2.74 Å. The Fe(1)-O(4) bond length is 1.99 Å. The Fe(1)-O(5) bond length is 2.25 Å. The Fe(1)-O(6) bond length is 2.61 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom to form distorted BiO6 octahedra that share  a cornercorner with one Cr(1)O5 trigonal bipyramid, edges with three equivalent Mg(1)O6 octahedra, and edges with two equivalent Cr(1)O5 trigonal bipyramids. The Bi(1)-O(1) bond length is 2.51 Å. The Bi(1)-O(2) bond length is 2.26 Å. The Bi(1)-O(3) bond length is 2.27 Å. The Bi(1)-O(4) bond length is 2.62 Å. The Bi(1)-O(5) bond length is 2.33 Å. The Bi(1)-O(6) bond length is 2.53 Å. In the second Bi site, Bi(2) is bonded in a 6-coordinate geometry to one O(1), one O(2), one O(3), one O(4), one O(5), and one O(6) atom. The Bi(2)-O(1) bond length is 2.41 Å. The Bi(2)-O(2) bond length is 2.66 Å. The Bi(2)-O(3) bond length is 2.36 Å. The Bi(2)-O(4) bond length is 2.24 Å. The Bi(2)-O(5) bond length is 2.54 Å. The Bi(2)-O(6) bond length is 2.24 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the third O site, O(3) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the fourth O site, O(4) is bonded in a 4-coordinate geometry to one Mg(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the fifth O site, O(5) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom. In the sixth O site, O(6) is bonded in a 5-coordinate geometry to one Mg(1), one Cr(1), one Fe(1), one Bi(1), and one Bi(2) atom.