MgCr2(BiO4)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted trigonal pyramidal geometry to two equivalent O(1) and two equivalent O(2) atoms. In the second Cr site, Cr(2) is bonded in a tetrahedral geometry to two equivalent O(3) and two equivalent O(4) atoms. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. In the second Bi site, Bi(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Cr(1) and one Bi(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Cr(2), one Bi(1), and one Bi(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Mg(1), one Cr(2), and one Bi(1) atom.
MgCr2(BiO4)2 crystallizes in the monoclinic C2 space group. Mg(1) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(4) atoms. Both Mg(1)-O(1) bond lengths are 2.03 Å. Both Mg(1)-O(4) bond lengths are 1.98 Å. There are two inequivalent Cr sites. In the first Cr site, Cr(1) is bonded in a distorted trigonal pyramidal geometry to two equivalent O(1) and two equivalent O(2) atoms. Both Cr(1)-O(1) bond lengths are 1.87 Å. Both Cr(1)-O(2) bond lengths are 1.78 Å. In the second Cr site, Cr(2) is bonded in a tetrahedral geometry to two equivalent O(3) and two equivalent O(4) atoms. Both Cr(2)-O(3) bond lengths are 1.79 Å. Both Cr(2)-O(4) bond lengths are 1.81 Å. There are two inequivalent Bi sites. In the first Bi site, Bi(1) is bonded in a 8-coordinate geometry to two equivalent O(1), two equivalent O(2), two equivalent O(3), and two equivalent O(4) atoms. Both Bi(1)-O(1) bond lengths are 2.71 Å. Both Bi(1)-O(2) bond lengths are 2.33 Å. Both Bi(1)-O(3) bond lengths are 2.52 Å. Both Bi(1)-O(4) bond lengths are 2.47 Å. In the second Bi site, Bi(2) is bonded in a 4-coordinate geometry to two equivalent O(1) and two equivalent O(3) atoms. Both Bi(2)-O(1) bond lengths are 2.38 Å. Both Bi(2)-O(3) bond lengths are 2.24 Å. There are four inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Mg(1), one Cr(1), one Bi(1), and one Bi(2) atom. In the second O site, O(2) is bonded in a 2-coordinate geometry to one Cr(1) and one Bi(1) atom. In the third O site, O(3) is bonded in a 3-coordinate geometry to one Cr(2), one Bi(1), and one Bi(2) atom. In the fourth O site, O(4) is bonded in a 2-coordinate geometry to one Mg(1), one Cr(2), and one Bi(1) atom.