MgCr(SiO3)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(4), and one O(6) atom. Cr(1) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-64°. In the second Si site, Si(2) is bonded to one O(4), one O(6), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-66°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one Si(2) atom. In the third O site, O(1) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Cr(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the sixth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Cr(1), and one Si(2) atom.
MgCr(SiO3)2 crystallizes in the monoclinic P2_1/c space group. Mg(1) is bonded in a distorted rectangular see-saw-like geometry to one O(1), one O(2), one O(4), and one O(6) atom. The Mg(1)-O(1) bond length is 1.98 Å. The Mg(1)-O(2) bond length is 2.05 Å. The Mg(1)-O(4) bond length is 2.04 Å. The Mg(1)-O(6) bond length is 1.97 Å. Cr(1) is bonded to one O(1), one O(6), two equivalent O(2), and two equivalent O(4) atoms to form CrO6 octahedra that share corners with three equivalent Si(1)O4 tetrahedra, corners with three equivalent Si(2)O4 tetrahedra, and edges with two equivalent Cr(1)O6 octahedra. The Cr(1)-O(1) bond length is 2.18 Å. The Cr(1)-O(6) bond length is 2.20 Å. There is one shorter (2.06 Å) and one longer (2.40 Å) Cr(1)-O(2) bond length. There is one shorter (2.06 Å) and one longer (2.39 Å) Cr(1)-O(4) bond length. There are two inequivalent Si sites. In the first Si site, Si(1) is bonded to one O(1), one O(2), and two equivalent O(5) atoms to form SiO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and corners with two equivalent Si(1)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 33-64°. The Si(1)-O(1) bond length is 1.61 Å. The Si(1)-O(2) bond length is 1.64 Å. There is one shorter (1.65 Å) and one longer (1.66 Å) Si(1)-O(5) bond length. In the second Si site, Si(2) is bonded to one O(4), one O(6), and two equivalent O(3) atoms to form SiO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra and corners with two equivalent Si(2)O4 tetrahedra. The corner-sharing octahedral tilt angles range from 42-66°. The Si(2)-O(4) bond length is 1.65 Å. The Si(2)-O(6) bond length is 1.61 Å. Both Si(2)-O(3) bond lengths are 1.66 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a distorted bent 150 degrees geometry to two equivalent Si(1) atoms. In the second O site, O(6) is bonded in a distorted trigonal planar geometry to one Mg(1), one Cr(1), and one Si(2) atom. In the third O site, O(1) is bonded in a distorted T-shaped geometry to one Mg(1), one Cr(1), and one Si(1) atom. In the fourth O site, O(2) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Cr(1), and one Si(1) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to two equivalent Si(2) atoms. In the sixth O site, O(4) is bonded in a distorted rectangular see-saw-like geometry to one Mg(1), two equivalent Cr(1), and one Si(2) atom.