Zn2As2O7 crystallizes in the monoclinic C2/m space group. Zn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted ZnO6 pentagonal pyramids that share corners with six equivalent As(1)O4 tetrahedra and edges with three equivalent Zn(1)O6 pentagonal pyramids. As(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form AsO4 tetrahedra that share corners with six equivalent Zn(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 distorted trigonal planar geometry to two equivalent Zn(1) and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Zn(1) and one As(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent As(1) atoms.
Zn2As2O7 crystallizes in the monoclinic C2/m space group. Zn(1) is bonded to two equivalent O(1) and four equivalent O(2) atoms to form distorted ZnO6 pentagonal pyramids that share corners with six equivalent As(1)O4 tetrahedra and edges with three equivalent Zn(1)O6 pentagonal pyramids. Both Zn(1)-O(1) bond lengths are 2.12 Å. There are two shorter (2.05 Å) and two longer (2.30 Å) Zn(1)-O(2) bond lengths. As(1) is bonded to one O(1), one O(3), and two equivalent O(2) atoms to form AsO4 tetrahedra that share corners with six equivalent Zn(1)O6 pentagonal pyramids and  a cornercorner with one As(1)O4 tetrahedra. The As(1)-O(1) bond length is 1.72 Å. The As(1)-O(3) bond length is 1.75 Å. Both As(1)-O(2) bond lengths are 1.71 Å. There are three inequivalent O sites. In the first O site, O(1) is bonded in a distorted trigonal planar geometry to two equivalent Zn(1) and one As(1) atom. In the second O site, O(2) is bonded in a distorted trigonal planar geometry to two equivalent Zn(1) and one As(1) atom. In the third O site, O(3) is bonded in a linear geometry to two equivalent As(1) atoms.