Ni2As2O7 crystallizes in the monoclinic C2/m space group. Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted NiO6 pentagonal pyramids that share corners with six equivalent As(1)O4 tetrahedra and edges with three equivalent Ni(1)O6 pentagonal pyramids. As(1) is bonded to one O(1), one O(2), and two equivalent O(3) atoms to form distorted AsO4 tetrahedra that share corners with six equivalent Ni(1)O6 pentagonal pyramids and  a cornercorner with one As(1)O4 tetrahedra. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent As(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ni(1) and one As(1) atom.
Ni2As2O7 crystallizes in the monoclinic C2/m space group. Ni(1) is bonded to two equivalent O(2) and four equivalent O(3) atoms to form distorted NiO6 pentagonal pyramids that share corners with six equivalent As(1)O4 tetrahedra and edges with three equivalent Ni(1)O6 pentagonal pyramids. Both Ni(1)-O(2) bond lengths are 2.11 Å. There are two shorter (2.08 Å) and two longer (2.14 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 distorted AsO4 tetrahedra that share corners with six equivalent Ni(1)O6 pentagonal pyramids and  a cornercorner with one As(1)O4 tetrahedra. The As(1)-O(1) bond length is 1.73 Å. The As(1)-O(2) bond length is 1.73 Å. Both As(1)-O(3) bond lengths are 1.71 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a linear geometry to two equivalent As(1) atoms. In the second O site, O(2) is bonded in a 3-coordinate geometry to two equivalent Ni(1) and one As(1) atom. In the third O site, O(3) is bonded in a distorted trigonal non-coplanar geometry to two equivalent Ni(1) and one As(1) atom.