Na4Cr2H6O11 crystallizes in the orthorhombic Fdd2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms. In the second Na site, Na(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with four equivalent Cr(1)O4 tetrahedra and corners with three equivalent Na(2)O5 trigonal bipyramids. Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CrO4 tetrahedra that share corners with four equivalent Na(2)O5 trigonal bipyramids. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. In the third H site, H(3) is bonded in a distorted single-bond geometry to one O(1) and one O(6) atom. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Cr(1), and one H(3) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Na(1) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to two equivalent Na(2) and two equivalent H(3) atoms.
Na4Cr2H6O11 crystallizes in the orthorhombic Fdd2 space group. There are two inequivalent Na sites. In the first Na site, Na(1) is bonded in a 7-coordinate geometry to one O(1), one O(2), one O(4), two equivalent O(3), and two equivalent O(5) atoms. The Na(1)-O(1) bond length is 2.48 Å. The Na(1)-O(2) bond length is 2.83 Å. The Na(1)-O(4) bond length is 2.68 Å. There is one shorter (2.43 Å) and one longer (2.51 Å) Na(1)-O(3) bond length. There is one shorter (2.39 Å) and one longer (2.48 Å) Na(1)-O(5) bond length. In the second Na site, Na(2) is bonded to one O(1), one O(4), one O(6), and two equivalent O(2) atoms to form distorted NaO5 trigonal bipyramids that share corners with four equivalent Cr(1)O4 tetrahedra and corners with three equivalent Na(2)O5 trigonal bipyramids. The Na(2)-O(1) bond length is 2.42 Å. The Na(2)-O(4) bond length is 2.40 Å. The Na(2)-O(6) bond length is 2.40 Å. There is one shorter (2.32 Å) and one longer (2.38 Å) Na(2)-O(2) bond length. Cr(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form CrO4 tetrahedra that share corners with four equivalent Na(2)O5 trigonal bipyramids. The Cr(1)-O(1) bond length is 1.68 Å. The Cr(1)-O(2) bond length is 1.66 Å. The Cr(1)-O(3) bond length is 1.66 Å. The Cr(1)-O(4) bond length is 1.67 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(5) atom. The H(1)-O(5) bond length is 0.99 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(5) atom. The H(2)-O(5) bond length is 0.98 Å. In the third H site, H(3) is bonded in a distorted single-bond geometry to one O(1) and one O(6) atom. The H(3)-O(1) bond length is 1.69 Å. The H(3)-O(6) bond length is 1.00 Å. There are six inequivalent O sites. In the first O site, O(1) is bonded in a 4-coordinate geometry to one Na(1), one Na(2), one Cr(1), and one H(3) atom. In the second O site, O(2) is bonded in a 4-coordinate geometry to one Na(1), two equivalent Na(2), and one Cr(1) atom. In the third O site, O(3) is bonded in a distorted T-shaped geometry to two equivalent Na(1) and one Cr(1) atom. In the fourth O site, O(4) is bonded in a 3-coordinate geometry to one Na(1), one Na(2), and one Cr(1) atom. In the fifth O site, O(5) is bonded in a distorted water-like geometry to two equivalent Na(1), one H(1), and one H(2) atom. In the sixth O site, O(6) is bonded in a distorted water-like geometry to two equivalent Na(2) and two equivalent H(3) atoms.