NaCr(SO4)2 crystallizes in the orthorhombic Pnma space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(4), and three equivalent O(2) atoms. Cr(1) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-41°. In the second S site, S(2) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-39°. There are six inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(1) atom. In the second O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(1) atom. In the third O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Na(1) and one S(2) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(2) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Cr(1), and one S(2) atom.
NaCr(SO4)2 crystallizes in the orthorhombic Pnma space group. Na(1) is bonded in a 6-coordinate geometry to one O(1), two equivalent O(4), and three equivalent O(2) atoms. The Na(1)-O(1) bond length is 2.39 Å. Both Na(1)-O(4) bond lengths are 2.52 Å. There is one shorter (2.36 Å) and two longer (2.75 Å) Na(1)-O(2) bond lengths. Cr(1) is bonded to one O(3), one O(5), two equivalent O(4), and two equivalent O(6) atoms to form CrO6 octahedra that share corners with three equivalent S(1)O4 tetrahedra and corners with three equivalent S(2)O4 tetrahedra. The Cr(1)-O(3) bond length is 2.00 Å. The Cr(1)-O(5) bond length is 2.05 Å. Both Cr(1)-O(4) bond lengths are 2.02 Å. Both Cr(1)-O(6) bond lengths are 2.00 Å. There are two inequivalent S sites. In the first S site, S(1) is bonded to one O(1), one O(5), and two equivalent O(6) atoms to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 38-41°. The S(1)-O(1) bond length is 1.45 Å. The S(1)-O(5) bond length is 1.50 Å. Both S(1)-O(6) bond lengths are 1.50 Å. In the second S site, S(2) is bonded to one O(2), one O(3), and two equivalent O(4) atoms to form SO4 tetrahedra that share corners with three equivalent Cr(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 25-39°. The S(2)-O(2) bond length is 1.46 Å. The S(2)-O(3) bond length is 1.48 Å. Both S(2)-O(4) bond lengths are 1.50 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(1) atom. In the second O site, O(6) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(1) atom. In the third O site, O(1) is bonded in a distorted bent 150 degrees geometry to one Na(1) and one S(1) atom. In the fourth O site, O(2) is bonded in a 4-coordinate geometry to three equivalent Na(1) and one S(2) atom. In the fifth O site, O(3) is bonded in a bent 150 degrees geometry to one Cr(1) and one S(2) atom. In the sixth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Cr(1), and one S(2) atom.