CaAsH5O6 crystallizes in the monoclinic Cc space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(6), and two equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. As(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form AsO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 64-76°. There are five 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 distorted linear geometry to one O(1) and one O(2) atom. In the third H site, H(3) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(5) atom. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to one O(3) and one O(6) atom. There are six inequivalent O sites. In the first O site, O(5) is bonded in a water-like geometry to one As(1) and one H(3) atom. In the second O site, O(6) is bonded in a 1-coordinate geometry to one Ca(1), one As(1), and one H(5) atom. In the third O site, O(1) is bonded in a 2-coordinate geometry to one Ca(1), one H(1), one H(2), and one H(3) atom. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Ca(1), one H(2), and one H(4) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one As(1), and one H(5) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one As(1) atom.
CaAsH5O6 crystallizes in the monoclinic Cc space group. Ca(1) is bonded to one O(1), one O(2), one O(3), one O(6), and two equivalent O(4) atoms to form distorted CaO6 octahedra that share corners with two equivalent Ca(1)O6 octahedra, corners with two equivalent As(1)O4 tetrahedra, and  an edgeedge with one As(1)O4 tetrahedra. The corner-sharing octahedral tilt angles are 42°. The Ca(1)-O(1) bond length is 2.61 Å. The Ca(1)-O(2) bond length is 2.39 Å. The Ca(1)-O(3) bond length is 2.32 Å. The Ca(1)-O(6) bond length is 2.71 Å. There is one shorter (2.41 Å) and one longer (2.42 Å) Ca(1)-O(4) bond length. As(1) is bonded to one O(3), one O(4), one O(5), and one O(6) atom to form AsO4 tetrahedra that share corners with two equivalent Ca(1)O6 octahedra and  an edgeedge with one Ca(1)O6 octahedra. The corner-sharing octahedral tilt angles range from 64-76°. The As(1)-O(3) bond length is 1.71 Å. The As(1)-O(4) bond length is 1.72 Å. The As(1)-O(5) bond length is 1.69 Å. The As(1)-O(6) bond length is 1.83 Å. There are five 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 0.99 Å. In the second H site, H(2) is bonded in a distorted linear geometry to one O(1) and one O(2) atom. The H(2)-O(1) bond length is 1.60 Å. The H(2)-O(2) bond length is 1.02 Å. In the third H site, H(3) is bonded in a distorted bent 150 degrees geometry to one O(1) and one O(5) atom. The H(3)-O(1) bond length is 1.04 Å. The H(3)-O(5) bond length is 1.53 Å. In the fourth H site, H(4) is bonded in a single-bond geometry to one O(2) atom. The H(4)-O(2) bond length is 0.99 Å. In the fifth H site, H(5) is bonded in a distorted single-bond geometry to one O(3) and one O(6) atom. The H(5)-O(3) bond length is 1.63 Å. The H(5)-O(6) bond length is 1.02 Å. There are six inequivalent O sites. In the first O site, O(5) is bonded in a water-like geometry to one As(1) and one H(3) atom. In the second O site, O(6) is bonded in a 1-coordinate geometry to one Ca(1), one As(1), and one H(5) atom. In the third O site, O(1) is bonded in a 2-coordinate geometry to one Ca(1), one H(1), one H(2), and one H(3) atom. In the fourth O site, O(2) is bonded in a distorted water-like geometry to one Ca(1), one H(2), and one H(4) atom. In the fifth O site, O(3) is bonded in a 3-coordinate geometry to one Ca(1), one As(1), and one H(5) atom. In the sixth O site, O(4) is bonded in a distorted trigonal planar geometry to two equivalent Ca(1) and one As(1) atom.