NiAsO4 crystallizes in the orthorhombic Pnma space group. Ni(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. As(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form AsO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-61°. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one As(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ni(1) and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one As(1) atom.
NiAsO4 crystallizes in the orthorhombic Pnma space group. Ni(1) is bonded to one O(1), one O(2), and four equivalent O(3) atoms to form NiO6 octahedra that share corners with four equivalent Ni(1)O6 octahedra, corners with four equivalent As(1)O4 tetrahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 46°. The Ni(1)-O(1) bond length is 1.94 Å. The Ni(1)-O(2) bond length is 1.93 Å. There are two shorter (2.01 Å) and two longer (2.16 Å) Ni(1)-O(3) bond lengths. As(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form AsO4 tetrahedra that share corners with four equivalent Ni(1)O6 octahedra and  an edgeedge with one Ni(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 46-61°. The As(1)-O(1) bond length is 1.72 Å. The As(1)-O(2) bond length is 1.71 Å. Both As(1)-O(3) bond lengths are 1.75 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Ni(1) and one As(1) atom. In the second O site, O(2) is bonded in a bent 120 degrees geometry to one Ni(1) and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal planar geometry to two equivalent Ni(1) and one As(1) atom.