Cs2H2P2O7 crystallizes in the monoclinic C2/c space group. Cs(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(3), and four equivalent O(2) atoms. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing PO4 tetrahedra. H(1) is bonded in a linear geometry to one O(1) and one O(3) atom. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one P(1), and one H(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1) and two equivalent P(1) atoms. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cs(1), one P(1), and one H(1) atom. In the fourth O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one P(1) atom.
Cs2H2P2O7 crystallizes in the monoclinic C2/c space group. Cs(1) is bonded in a 8-coordinate geometry to one O(1), one O(4), two equivalent O(3), and four equivalent O(2) atoms. The Cs(1)-O(1) bond length is 3.19 Å. The Cs(1)-O(4) bond length is 3.29 Å. There is one shorter (3.10 Å) and one longer (3.23 Å) Cs(1)-O(3) bond length. There are a spread of Cs(1)-O(2) bond distances ranging from 3.13-3.45 Å. P(1) is bonded to one O(1), one O(2), one O(3), and one O(4) atom to form corner-sharing PO4 tetrahedra. The P(1)-O(1) bond length is 1.59 Å. The P(1)-O(2) bond length is 1.51 Å. The P(1)-O(3) bond length is 1.52 Å. The P(1)-O(4) bond length is 1.65 Å. H(1) is bonded in a linear geometry to one O(1) and one O(3) atom. The H(1)-O(1) bond length is 1.04 Å. The H(1)-O(3) bond length is 1.50 Å. There are four inequivalent O sites. In the first O site, O(3) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1), one P(1), and one H(1) atom. In the second O site, O(4) is bonded in a distorted bent 120 degrees geometry to two equivalent Cs(1) and two equivalent P(1) atoms. In the third O site, O(1) is bonded in a distorted bent 120 degrees geometry to one Cs(1), one P(1), and one H(1) atom. In the fourth O site, O(2) is bonded in a distorted single-bond geometry to four equivalent Cs(1) and one P(1) atom.