NaNi2H3(SeO5)2 crystallizes in the monoclinic Cm space group. Na(1) is bonded to one O(3), one O(4), two equivalent O(7), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with three equivalent Se(1)O4 tetrahedra, and corners with three equivalent Se(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 69°. Ni(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form NiO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 69°. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. In the third H site, H(3) is bonded in a linear geometry to one O(1) and one O(2) atom. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(3), one O(5), and two equivalent O(7) atoms to form SeO4 tetrahedra that share corners with three equivalent Na(1)O6 octahedra and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-70°. In the second Se site, Se(2) is bonded to one O(4), one O(6), and two equivalent O(8) atoms to form SeO4 tetrahedra that share corners with three equivalent Na(1)O6 octahedra and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-71°. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ni(1), one H(1), and one H(3) atom to form distorted corner-sharing ONi2H2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Ni(1), one H(2), and one H(3) atom to form distorted corner-sharing ONi2H2 tetrahedra. In the third O site, O(3) is bonded in a distorted water-like geometry to one Na(1) and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Na(1) and one Se(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one Se(2) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Na(1), one Ni(1), and one Se(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Na(1), one Ni(1), and one Se(2) atom.
NaNi2H3(SeO5)2 crystallizes in the monoclinic Cm space group. Na(1) is bonded to one O(3), one O(4), two equivalent O(7), and two equivalent O(8) atoms to form distorted NaO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with three equivalent Se(1)O4 tetrahedra, and corners with three equivalent Se(2)O4 tetrahedra. The corner-sharing octahedral tilt angles are 69°. The Na(1)-O(3) bond length is 2.43 Å. The Na(1)-O(4) bond length is 2.44 Å. Both Na(1)-O(7) bond lengths are 2.56 Å. Both Na(1)-O(8) bond lengths are 2.56 Å. Ni(1) is bonded to one O(1), one O(2), one O(5), one O(6), one O(7), and one O(8) atom to form NiO6 octahedra that share corners with two equivalent Na(1)O6 octahedra, corners with two equivalent Se(1)O4 tetrahedra, corners with two equivalent Se(2)O4 tetrahedra, and edges with two equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles are 69°. The Ni(1)-O(1) bond length is 2.02 Å. The Ni(1)-O(2) bond length is 2.06 Å. The Ni(1)-O(5) bond length is 2.14 Å. The Ni(1)-O(6) bond length is 2.14 Å. The Ni(1)-O(7) bond length is 2.10 Å. The Ni(1)-O(8) bond length is 2.10 Å. There are three inequivalent H sites. In the first H site, H(1) is bonded in a single-bond geometry to one O(1) atom. The H(1)-O(1) bond length is 0.98 Å. In the second H site, H(2) is bonded in a single-bond geometry to one O(2) atom. The H(2)-O(2) bond length is 0.99 Å. In the third H site, H(3) is bonded in a linear geometry to one O(1) and one O(2) atom. The H(3)-O(1) bond length is 1.33 Å. The H(3)-O(2) bond length is 1.13 Å. There are two inequivalent Se sites. In the first Se site, Se(1) is bonded to one O(3), one O(5), and two equivalent O(7) atoms to form SeO4 tetrahedra that share corners with three equivalent Na(1)O6 octahedra and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 48-70°. The Se(1)-O(3) bond length is 1.64 Å. The Se(1)-O(5) bond length is 1.72 Å. Both Se(1)-O(7) bond lengths are 1.68 Å. In the second Se site, Se(2) is bonded to one O(4), one O(6), and two equivalent O(8) atoms to form SeO4 tetrahedra that share corners with three equivalent Na(1)O6 octahedra and corners with four equivalent Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 49-71°. The Se(2)-O(4) bond length is 1.65 Å. The Se(2)-O(6) bond length is 1.72 Å. Both Se(2)-O(8) bond lengths are 1.68 Å. There are eight inequivalent O sites. In the first O site, O(1) is bonded to two equivalent Ni(1), one H(1), and one H(3) atom to form distorted corner-sharing ONi2H2 tetrahedra. In the second O site, O(2) is bonded to two equivalent Ni(1), one H(2), and one H(3) atom to form distorted corner-sharing ONi2H2 tetrahedra. In the third O site, O(3) is bonded in a distorted water-like geometry to one Na(1) and one Se(1) atom. In the fourth O site, O(4) is bonded in a distorted water-like geometry to one Na(1) and one Se(2) atom. In the fifth O site, O(5) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one Se(1) atom. In the sixth O site, O(6) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one Se(2) atom. In the seventh O site, O(7) is bonded in a trigonal planar geometry to one Na(1), one Ni(1), and one Se(1) atom. In the eighth O site, O(8) is bonded in a trigonal planar geometry to one Na(1), one Ni(1), and one Se(2) atom.